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Kafflut

Kafflut
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I have been troubled by fast idle on K100. The idle speed control screw does not touch the stopper and when the bike is warm it idles at nearly 1500. Here's what I've done up to now:

1. I made sure there's free play in the cable.

2. Today I took the tank off and removed the cable, making absolutely sure that the cable is not interfering with the mechanism. It still seems to stop against something and cannot be adjusted lower.

3. I checked the fast idle. Cable free play is okay and where the little lever engages with the mechanism I can see daylight when the handlebar lever is closed. Only when the handle bar lever is activated and only when all the free play is taken up does it engage. So the fast idle mechanism is not interfering.

I have read in many places that if I touch the individual butterfly adjustment screws I should not expect life to ever be the same again - don't do it. But what if a previous owner has adjusted them?

The mechanism bottoms out against something before the idle control screw touches  the stopper. And at this bottom position it idles too fast. My conclusion is one of the butterflies bottoms out. Is this possible?

I thought I would seek advice before I remove the throttle bodies, turn the thing upside down and check out my theory. The thing is, what if this is the case? If my suspicion is confirmed I need to venture into that nether-world of adjusting the individual butterfly settings. Anybody have suggestions?



Last edited by Kafflut on Thu Dec 29, 2016 12:42 pm; edited 1 time in total

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Inge K.

Inge K.
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VIP
Check the TPS.....a wrong adjusted TPS can prevent the TB's from closing fully.


__________________________________________________
Inge K.
K100RS -86. (first owner), K1100LTSE -94.
    

charlie99

charlie99
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good suggestion inge

just undo the 2 screws that locate the tps switch at the end of the throttle bodies ....that may let it rotate back to the correct position ...but might be worthwhile giving the tps a small twist anticlockwise in any case ...

the idle adjust screw to the idleup bar does not always touch ....its usually adjusted for the correct high speed idle when the choke is utilised
and that bar is raised by the cable - cam actuation ....just observe it when you use the choke to the first position ...see if it touches then (oops you said that it does. sorry missed that before )?

the screws on the tps may be hard to get to ...mainly the one at the back
I use a ratchet handle type 1/4 inch drive with a short extension and Philips head adaptor to get in there easily
Fast Idle .... Latest: It is finally fixed! 20150913
good luck



Last edited by charlie99 on Wed Sep 09, 2015 5:57 pm; edited 1 time in total


__________________________________________________
cheezy grin whilst riding, kinda bloke ....oh the joy !!!! ...... ( brick aviator )

'86 K100 RT..#0090401 ..."Gerty" ( Gertrude Von Clickandshift ) --------O%OFast Idle .... Latest: It is finally fixed! Au-log10

'86 k100 rs.. #######..  "Fred " (f(rame) red ) ( Fredrick leichtundschnell ) - -
bits and pieces from many kind friends across the k100 world ...with many thanks ..
    

Motorbike Mike

Motorbike Mike
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If it were my bike I'd look to the choke side of the throttle bodies first if you have free play in the throttle cable. I've had a problem there before with a badly adjusted cable from a previous owner.
If you suspect mal-adjustment of the butterflies, before you remove them, put a set of vacuum gauges on the bike. If things aren't adjusted properly the gauges will tell you straight away.

Good luck.

    

5Back to top Go down   Fast Idle .... Latest: It is finally fixed! Empty Fast Idle Wed Sep 09, 2015 7:34 pm

RT

RT
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MIne was TPS, after 2 years of adjusting everything including T/B butterflies. The TPS was fitted in  a way that didn't let the idle screw arm(throttle arm end fits in to the TPS) drop all the way down.
Could be lots of things but go simple first.


__________________________________________________
2011 R1200RT
    

6Back to top Go down   Fast Idle .... Latest: It is finally fixed! Empty The fast idle is now worse Thu Sep 10, 2015 2:31 am

Kafflut

Kafflut
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Silver member
Thank you everyone, for the suggestions. I'm glad I asked before dismantling TB assembly. I will check the TPS today. I listened for that "click" on previous occasions and it does do that when opening up, but I'll loosen the switch and see if it makes a difference.

Thanks again.

Since I posted this I have tried many things and the idle remains too fast. I went for a ride and when the engine had warmed up it was embarrassing to stop at lights - while waiting for the light to change I held the brake, closed the throttle and slipped the clutch to control the noise some.

It is now running at between 1500 rpm and 2000 rpm with the throttle closed! Even when cold. It seems to go faster then slower then faster again, doesn't run evenly at the same revs. It starts easily, first turn.

Here are some of the things I've "eliminated" as the possible cause. I'd welcome suggestions for what next to try.

1. I have another K100 of similar vintage and was able to swap out components one at a time. I've included the diagram in order to refer to items.


Fast Idle .... Latest: It is finally fixed! Principal1

Swapped Ignition module (5) Fuel pressure regulator (7) Fuel injection module (10) Air manifold (12) complete with TBs. There is no change.

2. I undid the throttle and the fast idle (choke) cables. I took off the TPS.
 
3. I fitted a T-piece in the fuel pump to fuel rail line and connected a pressure gauge - 40 psi running at about 1700 rpm.

4. I turned the air bypass setting(14) on the air flow meter 3 full turns anti clockwise, then back to where it was, then 1 full turn clockwise. No change. I turned it back to where it was.

5. I tried with and without the air filter element.

If anybody has a suggestion for the most likely next thing to try I'd be glad to give it a shot.



Last edited by Kafflut on Fri Oct 16, 2015 9:58 am; edited 1 time in total (Reason for editing : I still have the fast idle + a lot more information)

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Kafflut

Kafflut
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Silver member
Later: I removed the TPS. Nope, no difference; still blue sky between the idle adjust screw and the stopper. I guess I'll be taking off the TB assembly and shine some light in there to see what's going on inside.

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charlie99

charlie99
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there should be blue sky between the two ......until you put the choke to first or second position


__________________________________________________
cheezy grin whilst riding, kinda bloke ....oh the joy !!!! ...... ( brick aviator )

'86 K100 RT..#0090401 ..."Gerty" ( Gertrude Von Clickandshift ) --------O%OFast Idle .... Latest: It is finally fixed! Au-log10

'86 k100 rs.. #######..  "Fred " (f(rame) red ) ( Fredrick leichtundschnell ) - -
bits and pieces from many kind friends across the k100 world ...with many thanks ..
    

Kafflut

Kafflut
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Silver member
Thanks, Charlie99. There's something I'm not getting. The image below shows the gap I'm talking about. Something prevents the butterfly valves from being closed further. With accelerator cable and fast idle(choke/cold start) cable removed and the TPS removed the throttle butterfly linkage remains in the same position ie. the engine would idle at about 1500 rpm

Fast Idle .... Latest: It is finally fixed! 2177075_orig

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92KK 84WW Olaf

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I had this issue on my LT, it was caused by a worm drive clip fouling the mechanism, loosening off and rotating the clip solved the problem. My ex BMW friend found it by pressing the mechanism down to close that gap which told us an obstruction was the problem. Seems its not uncommon.


__________________________________________________
1992 K100LT 0193214 Bertha Blue 101,000 miles
1984 K100RT 0022575 Brutus Baja Red 578 bought 36,000 now 89,150 miles
1997 K1100LT 0188024 Wotan Mystic Red 689 58,645 now 106,950 miles Deceased.
1983 K100RS 0011171 Fricka 606 Alaska Blue 29,495 miles Damn K Pox Its a Bat outta Hell Now 37,190 miles. 
1996 K1100LT 0233004 Lohengrin Mystic Red 38,000 miles currently 42,640 miles.

Past:
1968 Yamaha 80 YG1
1971 Yamaha 125 YAS-1
1968 Honda 125 SS
1970 Honda CD 175
1973 Honda CB500-4
Honda CX 500
    

robmack

robmack
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That screw you're pointing out is not the idle adjust screw. It is a main throttle adjust screw however it is there to limit the rotational travel of the throttle, not to set the idle speed.

There are four brass coloured screws on top of throttle body assembly, one per TB. These are the idle adjust screws. They also server the purpose of balancing the TBs. You need a manometer to perform the balance procedure and to set the idle speed. This is the balancing procedure.

The main throttle adjust screw does not touch the stop plate because the butterfly valves are fully closed. That's where the 0.2mm gap comes in. You should adjust that screw only so it just contacts the plate when the TB is fully closed.

Don't start messing with the interbody linkage screws. That will not solve your problem, but once altered they will bring you more problems than an abnormally fast idle.


__________________________________________________
Robert
1987 K75 @k75retro.blogspot.ca
http://k75retro.blogspot.ca/
    

Motorbike Mike

Motorbike Mike
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@92KK 84WW Olaf wrote:I had this issue on my LT, it was caused by a worm drive clip fouling the mechanism, loosening off and rotating the clip solved the problem. My ex BMW friend found it by pressing the mechanism down to close that gap which told us an obstruction was the problem. Seems its not uncommon.
I've had/done that too. Check the hose clip bodies as they can easily foul the mechanism.
The screw shown in the earlier image is the idle adjustment screw-it is on all my K series 4's for sure. That screw stops the butterflies shutting all together. I've just checked two of my bikes and the screw sits onto the tab and that's 1000 and 1100's.

When you ask for fast idle on a cold engine, that's when there's a gap present as the "choke" switch pulls the TB's open a little more to give the engine fast idle. When the engine's warm and all cables are at rest there shouldn't be a gap under that screw.

    

walfish

walfish
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You're on the button there MM, a badly adjusted Fast idle cable. I spent many long hours to get mine right

Fast Idle .... Latest: It is finally fixed! 22936


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Fast Idle .... Latest: It is finally fixed! Uk-log10 88 K 100  0033026 
   
                            92 K 1100 LT  6455097
    

robmack

robmack
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Refer to the following diagram:

Fast Idle .... Latest: It is finally fixed! Thrott10

There is a fast idle cable not shown on this diagram  that terminates on a lever arm right beside the TPS (6).  If this cable is maladjusted, the cam could put pressure on the butterflies and open them slightly.  This is what ungaas refers to.  There is a threaded barrel into which the cable goes and that can be adjusted as to tighten or slacken the cable.

The other cause might be the TPS itself but you've checked that.

Once you've determined that nothing hinders the rotation of the butterflies, set the main throttle adjustment screw (2) so that it contacts the plate.  This prevents further clockwise rotation of the butterflies.  Use the idle adjustment screws (1) to set the idle speed.  Turn them clockwise to lower the idle speed; counter-clockwise to raise the idle speed.  Turn all equally and observe the change before trying another adjustment. Turn them 1/4 to 1/2 turn at a time only.  What happens is these air bleed screws will allow more or less air into the TB by bypassing the butterflies.  The main throttle adjustment screw (2) is not an idle adjuster; that's why the same screw on the K1100 is buried and inaccessible.


__________________________________________________
Robert
1987 K75 @k75retro.blogspot.ca
http://k75retro.blogspot.ca/
    

Kafflut

Kafflut
Silver member
Silver member
I eventually removed the whole air box, throttle assembly. There is nothing that interferes with the mechanism that I can see.

I omitted to mention in my post that this fast idle happened kinda sudden. One day the idle was cool, next time out it was up there near 1500. Something changed.

I applied a trick my friend Peter, a toolmaker/motorbike mechanic of note, gave me once; using a strip of magnetic tape as a kind of feeler gauge I compared the butterfly valves. No 1 bottoms out before 2, 3 and 4. But IMO not to the extent it warrants fiddling with. I figure the difference in airflow can be sorted out with balancing, which I will do last.

However, I may have located the problem. There's a breather pipe from crank case to the air box. It is perished, broken in two. As you know, the breather tube is connected to the air supply after the air flow meter. Probably the engine is getting air that the computer does not know about.

I'll be putting the whole lot together after fixing the breather thing, do ignition timing, do valve clearance.

Thank you all for the helpful comments.

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Dai

Dai
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That's it. Common problem - I think we've all been there.


__________________________________________________
1983 K100 upgraded to K100RS spec, 1987 K100RT
Others...
1978 Moto Guzzi 850-T3, 1979 Moto Guzzi 850-T3 California,1993 Moto Guzzi 1100ie California
2020 Royal Enfield Bullet 500
    

Kafflut

Kafflut
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@Kafflut wrote:Thank you everyone, for the suggestions. I'm glad I asked before dismantling TB assembly. I will check the TPS today. I listened for that "click" on previous occasions and it does do that when opening up, but I'll loosen the switch and see if it makes a difference.

Thanks again.

Since I posted this I have tried many things and the idle remains too fast. I went for a ride and when the engine had warmed up it was embarrassing to stop at lights - while waiting for the light to change I held the brake, closed the throttle and slipped the clutch to control the noise some.

It is now running at between 1500 rpm and 2000 rpm with the throttle closed! Even when cold. It seems to go faster then slower then faster again, doesn't run evenly at the same revs. It starts easily, first turn.

Here are some of the things I've "eliminated" as the possible cause. I'd welcome suggestions for what next to try.

1. I have another K100 of similar vintage and was able to swap out components one at a time. I've included the diagram in order to refer to items.


Fast Idle .... Latest: It is finally fixed! Principal1

Swapped Ignition module (5) Fuel pressure regulator (7) Fuel injection module (10) Air manifold (12) complete with TBs. There is no change.

2. I undid the throttle and the fast idle (choke) cables. I took off the TPS.
 
3. I fitted a T-piece in the fuel pump to fuel rail line and connected a pressure gauge - 40 psi running at about 1700 rpm.

4. I turned the air bypass setting(14) on the air flow meter 3 full turns anti clockwise, then back to where it was, then 1 full turn clockwise. No change. I turned it back to where it was.

5. I tried with and without the air filter element.

If anybody has a suggestion for the most likely next thing to try I'd be glad to give it a shot.
I forgot to mention, I also balanced the TBs

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18Back to top Go down   Fast Idle .... Latest: It is finally fixed! Empty Fast Idle Fri Oct 16, 2015 6:50 pm

RT

RT
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I suffered the same problem for a few years, tore all my hair out (both of them) and it indeed ended up being the TPS.
I eventually removed the TPS assembly, it just pulls off. What had happened was earleir I had put it on in such a way that it would not allow the idle arm to drop low enough to close off the throttle to idle speed. The problem forced me to do all my throttle body rubbers, vacuum hoses, manifold throttle rubbers etc before I just decided to pull it all apart. Starting with TPS off and immediately I saw my problem. No one else to blame, I mustve done it
4 years ago. Since re alinging it I've had constant 950 rpm hot or cold.


__________________________________________________
2011 R1200RT
    

Kafflut

Kafflut
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Silver member
Thanks RT. I took off the TPS early in the process. It's not that. I removed both cables as well. There is nothing opening the butterflies or preventing them shutting. It's weird. The engine will go 2000 rpm with the throttle mechanism completely SHUT, like press-down-on-it-with-your-finger shut.

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RicK G

RicK G
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Have you had the throttle bodies off to make sure there are no splits in the rubber manifolds or leaks under them? It is very common to have this.
Blue arrows point to the adjuster screws between the throttle bodies and look to me like they have been altered.
Red arrows point to the vacuum take offs to connect the manometers to and #4 should have a rubber line with a covering spiral wound wire protector and should go to the Fuel Pressure Regulator.
Green arrow points to the adjuster screws and at the base where I indicated with blue there should be some blue paint as a tell tale so it can be seen if they have been tampered with, is that blue paint there?
Fule pressure should be 2.5 bar which is 36PSI, your reading of 40PSI could be an inacurate gauge so I would not read anything into that yet.
The butterflies have to be all closed completly at idle with the only air getting into the combustion chamber being through the idle screw (Yellow Dot) adjuster air passage.
The adjustment screw you indicate should be against the stop so that the butterflies aren't taking the weight when the throttle is snapped back to idle.
Fast Idle .... Latest: It is finally fixed! Image111


__________________________________________________
"Man sacrifices his health in order to make money.
Then he sacrifices money to recuperate his health.
And then he is so anxious about the future that he does not enjoy the present; the result being that he does not live in the present or the future; he lives as if he is never going to die, and then dies having never really lived."   Dalai Lama


Bikes 2004 K1200GT 1998 K1100 LT, 1993 K75 RT, 1996 K75RT, 1986 K75 GS, 1979 Z1300 Kawasaki
    

robmack

robmack
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In Post #15, Kafflut said he fixed the problem by replacing the "Z" tube which was broken. I guess the upsurge to diagnose a non-existant problem is because he quoted a much earlier thread in his reply.


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Robert
1987 K75 @k75retro.blogspot.ca
http://k75retro.blogspot.ca/
    

Kafflut

Kafflut
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Hello Rick & Rob

Yes, in post 15 I thought I had found the reason, but the idle revs(throttle completely closed revs) kept creeping up again. It is now 1500 at best and just below 2000 most times.

But watch this space, I am not yet out of things to try Smile 

In Re: Fast Idle on Fri Oct 16, 2015 7:33 pm, I think it was post 17, I quoted the list of all I've done so far.

In the context of air leaks & TBs, I swapped the whole assembly, TB's, throttle assembly, rubbers etc. as a unit and it made no change. Check out that post. All I have not yet swapped out that in my opinion could contribute to the situation are injectors and air flow meter. That is today's job.

I am very much in the dark here, but check out my logic on:

1. Air leaks - The butterflies are all shut. I press down with my finger on the mechanism and it is shut. Whatever air, leaking or otherwise, is entering the combustion area through the completely shut butterflies! Is this possible? Both cables are disconnected and the TPS is disconnected.

2. I have swapped out components one at a time and the problem remained unchanged. My feeling is that it is very unlikely I have exchanged a faulty component with another that has the same fault.

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23Back to top Go down   Fast Idle .... Latest: It is finally fixed! Empty Post 22 update Sun Oct 18, 2015 6:10 am

Kafflut

Kafflut
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Read post 22 as well.

I have now swapped out the air flow meter as well. No change. The engine starts immediately and runs at 2000+ rpm with the butterfly valves shut. I'm out of ideas.

Additional information: With the air filter housing(including the AFM) disconnected from the plenum chamber the engine does not start. I have the top half of the air filter housing in my hands and I have access to the intake of the AFM. I depress by hand the little flap inside, maybe 5 or so mm. The engine starts immediately and idles at 900 rpm as long as I hold the little flap at that 5mm position.

Manually operating the AFM flap: below 5mm the engine stops - increasing it beyond 5 mm the engine runs a little faster up to about 2000 rpm - increasing it beyond that causes the engine to stop.

Manually holding the AFM flap at 5mm and opening the throttle the engine stops immediately.

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RicK G

RicK G
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using a strip of magnetic tape as a kind of feeler gauge I compared the butterfly valves. No 1 bottoms out before 2, 3 and 4.


Is this still the case or have you fixed it, If not it will contribute to the problem.
And have you checked the valve clearances because tight inlets will also contribute.
If you ride the clutch at a stop so the engine is bought back to about 1000rpm does it immediately go back to 1500rpm or does it gradually build over a period of about 5 seconds which is what happens with a lean mixture whether it is from air leaks or fuel starvation.


__________________________________________________
"Man sacrifices his health in order to make money.
Then he sacrifices money to recuperate his health.
And then he is so anxious about the future that he does not enjoy the present; the result being that he does not live in the present or the future; he lives as if he is never going to die, and then dies having never really lived."   Dalai Lama


Bikes 2004 K1200GT 1998 K1100 LT, 1993 K75 RT, 1996 K75RT, 1986 K75 GS, 1979 Z1300 Kawasaki
    

Kafflut

Kafflut
Silver member
Silver member
Thanks, Rick.

I have replaced the whole assembly, from plenum chamber to throttle bodies, as a unit. I compared the butterfly valves of the "new" one before fitting it, using my magnetic tape, and they are all the same. The "new" one gives exactly the same result as the old one. I figure, either it has the same fault as the other one, unlikely, or it is not what's causing the problem.

Fast Idle .... Latest: It is finally fixed! EFI-Flow%20Chart-graphical

Refer to the diagram. I have not swapped the following items: Hall sensors, fuel injectors, water temp sensor, coils, ignition switch, fuel injection relay and engine of course. I mean literally, I swapped them with other assemblies or components that were working in the bike they came from. I even ran a test with clean, different fuel to make sure the fuel had not become contaminated.

I have literally replaced all inputs to the EFI except water temperature and I have replace the EFI itself.

Yes, the valve clearances are within spec. And when I keep the revs low by slipping the clutch it picks up revs immediately when releasing the clutch.

And I have disconnected the temperature sensor - it does not start.



Last edited by Kafflut on Mon Oct 19, 2015 10:59 am; edited 2 times in total (Reason for editing : typo)

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Kafflut

Kafflut
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Silver member
Guesswhat, my engine is idling. No more 2000 + rpm It is running at 900 rpm. But I'm not out of the woods yet. Here's what I did:

I disconnected the temperature sensor & connected a 20K resistance in its place. One side of the resistor connected to #10 wire i.e. the top connector of the temperature sensor plug and the other side of the resistance to earth. Starts first turn and runs at 900.

I substituted the resistance with a 750 ohm, runs fast. Then a 1.5K, runs fast. Then disconnected, i.e. infinite ohms, does not start.

Reason I say I'm not out of the woods is I read somewhere else here that at normal temperature the resistance should be somewhere around 1000 ohm, I think.

I need to keep in mind that there is also the matter of the fan.

It is obvious now - running too fast has something to do with the temperature sensor that's in the bike or the wiring connecting it to the EFI. It's not the EFI. Both EFIs I tried give the same result. It seems to me a too low resistance reading is input to the EFI.

I will be quiet for a while and listen for input from people who know stuff Very Happy

I will now have coffee, make lunch for me and my lovely wife who's having a mid-morning nap and I will think.

I'm happy though - I have a different, repeatable result.
One can move forward from there.

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Holister

Holister
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Good find. You can test the water temp sensor by measuring the impedance from pin #10 to earth on the FICU plug.
Should be 2.5KΩ @20 ̊C
Instructions are in the trouble shooting page off the Portal tab about ¾ way down the page
Fast Idle .... Latest: It is finally fixed! Water%20temperature


__________________________________________________

1989 K100RT     VIN  0097367 (naked)  
1996 K1100RS   VIN  0451808
  Fast Idle .... Latest: It is finally fixed! Austra12    Fuel:  95 Octane
Engine Oil: Nulon Full Synthetic 15W50
Gear Box Oil:  Nulon Synthetic 75W90
    

Kafflut

Kafflut
Silver member
Silver member
Kaptain Holister wrote:Good find. You can test the water temp sensor by measuring the impedance from pin #10 to earth on the FICU plug.
Should be 2.5KΩ @20 ̊C
Instructions are in the trouble shooting page off the Portal tab about ¾ way down the page

Thank you. I measured the resistance as you suggest - 2.0K
I substituted the temperature sensor with a combination of resistors near 2.5K in total, measured again - 2.47K
Started the bike, it runs fine and idles at 900 rpm Very Happy

It makes me think: That sucker is very important; there's not much temperature difference between the 2.5K resistance and 2.0K and it made a big difference in idle rpm for me. What effect on fuel consumption if the sensor is faulty?

The long saga finally lurches towards conclusion - replace temperature sensor, hold thumbs and maybe get better fuel consumption too

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Holister

Holister
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"That sucker is VERY important". It will have been running a little lean.

The difference between 2.0Ω and 2.5Ω equates to about 10°c. Plenty enough to affect injection times.


__________________________________________________

1989 K100RT     VIN  0097367 (naked)  
1996 K1100RS   VIN  0451808
  Fast Idle .... Latest: It is finally fixed! Austra12    Fuel:  95 Octane
Engine Oil: Nulon Full Synthetic 15W50
Gear Box Oil:  Nulon Synthetic 75W90
    

Kafflut

Kafflut
Silver member
Silver member
I believe I'm in danger of winning this one. However, it is not yet won.

Current status: I have the idle down to just below 1000rpm. Idle rpm does not rush up to 2000 when the engine is warm. It starts easily and runs fine. I can also turn the throttle adjustment screw in (clockwise) to where it actually touches the stopper! This is how it should be, normal  Very Happy for a change! Up to now I've not been able to do that - I had it screwed right out else it would idle too fast. During this whole saga I discovered a number of things  that make me suspect I have been/am dealing with several matters, not just one:

. I cleaned the main earth connection and that made the idling more steady.

. I cleaned the spark plug caps and leads. While doing this I by chance noticed a movement inside #1 spark plug cap. Light and a closer look revealed that there was a spark plug ferrule/nipple sitting sideways in the bottom of the thing. I had noticed that the cap would not fit well over the plug, had been sticking out some. I removed that obstacle and there was a significant improvement - I thought I had detected misfiring before. I had definitely seen a spark or two between #1 spark plug cap and cylinder head.

. There was a little leak between the TB #2 rubber and cylinder head. I only detected this after repeated air-leak searches, spraying injector cleaning fluid. Although small I think this was the major factor. I removed all four rubbers, cleaned and refitted with a bit of gasket maker.


Remaining Problems: It does not idle smoothly. It does not misfire, but rpm seems to very briefly increase or decrease - I'm not certain which - I think it's increase. It is a very short change in the engine sound. The green neutral indicator light goes slightly dimmer when this hiccup in idling happens - an ever-so-slight blip in brightness.


Very Puzzling: I'm reluctant to mention this - it is bizarre to the point where some will think, he's-been-smoking-something! If I sit on the bike and engine running and I lean the bike slightly, the rpm changes Shocked Upright rpm = 1000, left a few degrees rpm > 1000, not much but noticeable. Lean right a little rpm < 1000 - again not much but noticeable.

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K75cster

K75cster
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Wouldn't the variance when leaning be the flap moving as a consequence???? The Air flap if it moves changes the reading at the FI Unit under the seat.


__________________________________________________
Keith - 1987 K75c with r100rt replica fairing and half of a 1984 K100rt 1992 K1100LT a blue one

The Clever are adept at extricating themselves from situations that the wise would have avoided from the outset - QUOTE from david Hillel in Out of the Earth.
    

RicK G

RicK G
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Great to read you are getting somewhere.
"The green neutral indicator light goes slightly dimmer when this hiccup in idling happens - an ever-so-slight blip in brightness."
I would not read a great deal into this at the moment but it should not be discarded, it could well be the charging system changing state at the rev increase.
If you have a set of gauges or manometer set them up and see if one cylinder shows very little change as you turn the big brass screws in and out which would indicate a leak is still present below the butterfly. Even without the gauges you may pick up on the change in the other cylinders.  I had to do that with my K100. The only solution was new manifold rubbers
it is very unlikely but even a bad valve guide and seal can let air through.


__________________________________________________
"Man sacrifices his health in order to make money.
Then he sacrifices money to recuperate his health.
And then he is so anxious about the future that he does not enjoy the present; the result being that he does not live in the present or the future; he lives as if he is never going to die, and then dies having never really lived."   Dalai Lama


Bikes 2004 K1200GT 1998 K1100 LT, 1993 K75 RT, 1996 K75RT, 1986 K75 GS, 1979 Z1300 Kawasaki
    

RicK G

RicK G
admin
admin
@K75cster wrote:Wouldn't the variance when leaning be the flap moving as a consequence???? The Air flap if it moves changes the reading at the FI Unit under the seat.
The MAF sensor wont move till above idle when the butterflys are opened, when there is sufficient air flow, there is a bypass for idle air.


__________________________________________________
"Man sacrifices his health in order to make money.
Then he sacrifices money to recuperate his health.
And then he is so anxious about the future that he does not enjoy the present; the result being that he does not live in the present or the future; he lives as if he is never going to die, and then dies having never really lived."   Dalai Lama


Bikes 2004 K1200GT 1998 K1100 LT, 1993 K75 RT, 1996 K75RT, 1986 K75 GS, 1979 Z1300 Kawasaki
    

Holister

Holister
Life time member
Life time member
Is your starter button missing? If the spring is gone the contacts can intermittantly close causing the FICU to slightly richen the mix resulting in a higher idle.

@kafflut wrote:..... there was a spark plug ferrule/nipple sitting sideways in the bottom of the thing. 
Just out of interest, NKG call this thingy a "terminal nut"


__________________________________________________

1989 K100RT     VIN  0097367 (naked)  
1996 K1100RS   VIN  0451808
  Fast Idle .... Latest: It is finally fixed! Austra12    Fuel:  95 Octane
Engine Oil: Nulon Full Synthetic 15W50
Gear Box Oil:  Nulon Synthetic 75W90
    

RicK G

RicK G
admin
admin
It will only do that below 711 RPM above that the feature is disabled.


__________________________________________________
"Man sacrifices his health in order to make money.
Then he sacrifices money to recuperate his health.
And then he is so anxious about the future that he does not enjoy the present; the result being that he does not live in the present or the future; he lives as if he is never going to die, and then dies having never really lived."   Dalai Lama


Bikes 2004 K1200GT 1998 K1100 LT, 1993 K75 RT, 1996 K75RT, 1986 K75 GS, 1979 Z1300 Kawasaki
    

Kafflut

Kafflut
Silver member
Silver member
@RicK G wrote:If you have a set of gauges or manometer set them up and see if one cylinder shows very little change as you turn the big brass screws in and out which would indicate a leak is still present below the butterfly. Even without the gauges you may pick up on the change in the other cylinders.  I had to do that with my K100. The only solution was new manifold rubbers
it is very unlikely but even a bad valve guide and seal can let air through.

Thanks Rick. I will try that. I will order manifold rubbers anyway.

It's interesting to note that after the cleaning & gasket-maker job on the manifold rubbers I was able to adjust the idling by turning the by-pass screw at the AFM. Before that, adjustments to the by-pass screw, even by several turns, had zero effect on idle rpm. My guess is that by-pass air at the AFM was insignificant compared to the air leaking at the TB rubbers.

http://bmwk100k75.weebly.com/
    

Kafflut

Kafflut
Silver member
Silver member
Kaptain Holister wrote:Is your starter button missing? If the spring is gone the contacts can intermittantly close causing the FICU to slightly richen the mix resulting in a higher idle.

@kafflut wrote:..... there was a spark plug ferrule/nipple sitting sideways in the bottom of the thing. 
Just out of interest, NKG call this thingy a "terminal nut"

Thanks, Kaptein. I've often wondered what to call that thingy. I would never have guessed "terminal nut" That's what my wife calls me when displeased. Sometimes it's "terninal ..." other stuff way worse than nut Very Happy

I tossed the starter/cut out switch combo a while ago for that very reason. I replaced it with an after market starter button and a regular on/off switch.

http://bmwk100k75.weebly.com/
    

Holister

Holister
Life time member
Life time member
@RicK G wrote:It will only do that below 711 RPM above that the feature is disabled.
That's what I thought but I had the same problem as kafflut.... pull up at lights and the engines idling at 2k or more. I thought it was related to overheating as it only seemed to happen after a decent long distance run or in hot weather,  but when I replaced my starter button so it worked properly, that symptom disappeared. 
Now from a cold start it idles at 950ish but once hot idle is at around 1200. My water temp sensor tests OK.


__________________________________________________

1989 K100RT     VIN  0097367 (naked)  
1996 K1100RS   VIN  0451808
  Fast Idle .... Latest: It is finally fixed! Austra12    Fuel:  95 Octane
Engine Oil: Nulon Full Synthetic 15W50
Gear Box Oil:  Nulon Synthetic 75W90
    

39Back to top Go down   Fast Idle .... Latest: It is finally fixed! Empty As good as it gets Sat Dec 19, 2015 11:50 am

Kafflut

Kafflut
Silver member
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I think I have reached that point, the point of as good as it gets.

It idles at just below 1000 rpm even after it has warmed up. Starts easily enough. When it's been standing for a number of days it takes a bit longer to start.

My first check on fuel consumption was over a distance of 100km. It was very good but I did not trust it because of the short distance.

Today I filled up the tank again. This time I'd done nearly 500 km. Consumption 3.48 litres / 100 km. Now that sounds too good to be true and you know what they say about sounds too good to be true. I checked my numbers and calculations.

I rode at between 90 and 100 km per hour mostly. I observed 60km speed limit where it occurred. So my speed was quite low.

Would fiddling with the idle air bypass at the AFM input affect fuel mixture at speed? Could it be that it is running lean?

http://bmwk100k75.weebly.com/
    

charlie99

charlie99
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the idle air bypass will have little effect once you open the throttle a bit

it relies on the butterflies being closed before air will pass through the restriction .

but it does sound like its running lean to me ...more noticed as the engine heats up

I guess you've tried all the usual culprits ....throttle body rubbers ....engine breather tube to plenum  as others have mentioned before .

sometimes taking the engine to throttle body rubbers off ....resealing with a good silicon at the base of the head after a cleanup ...will do wonders


__________________________________________________
cheezy grin whilst riding, kinda bloke ....oh the joy !!!! ...... ( brick aviator )

'86 K100 RT..#0090401 ..."Gerty" ( Gertrude Von Clickandshift ) --------O%OFast Idle .... Latest: It is finally fixed! Au-log10

'86 k100 rs.. #######..  "Fred " (f(rame) red ) ( Fredrick leichtundschnell ) - -
bits and pieces from many kind friends across the k100 world ...with many thanks ..
    

RicK G

RicK G
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That is a bit better than I would expect but not out of the bounds of reality. I would be inclined to go for a run at around 110kph and see what it shows. Anything from 4.7 to 5.5 seems to be within the normal range from my experience.


__________________________________________________
"Man sacrifices his health in order to make money.
Then he sacrifices money to recuperate his health.
And then he is so anxious about the future that he does not enjoy the present; the result being that he does not live in the present or the future; he lives as if he is never going to die, and then dies having never really lived."   Dalai Lama


Bikes 2004 K1200GT 1998 K1100 LT, 1993 K75 RT, 1996 K75RT, 1986 K75 GS, 1979 Z1300 Kawasaki
    

Kafflut

Kafflut
Silver member
Silver member
@charlie99 wrote:the idle air bypass will have little effect once you open the throttle a bit

it relies on the butterflies being closed before air will pass through the restriction .

but it does sound like its running lean to me ...more noticed as the engine heats up

I guess you've tried all the usual culprits ...
Thanks Charlie.
Yes, I tried the "usual culprits"
I agree, it sounds like it's running lean. But I don't think that's adjustable other than making changes to the fuel injection electronics?

http://bmwk100k75.weebly.com/
    

Kafflut

Kafflut
Silver member
Silver member
@RicK G wrote:That is a bit better than I would expect but not out of the bounds of reality. I would be inclined to go for a run at around 110kph and see what it shows. Anything from 4.7 to 5.5 seems to be within the normal range from my experience.
I intend doing that. I was very surprised. What I'll also be doing is to record where I ride and then check my odometer distance against the map distances - make sure that distance travelled is more or less right.

Would the air by-pass screws on the TB's be a way of adjusting the air/fuel mix? IMO that is just for balancing and would not have a major effect on lean or rich. 

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charlie99

charlie99
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@Kafflut wrote:
@charlie99 wrote:the idle air bypass will have little effect once you open the throttle a bit

it relies on the butterflies being closed before air will pass through the restriction .

but it does sound like its running lean to me ...more noticed as the engine heats up

I guess you've tried all the usual culprits ...
Thanks Charlie.
Yes, I tried the "usual culprits"
I agree, it sounds like it's running lean. But I don't think that's adjustable other than making changes to the fuel injection electronics?

the afm is where it all happens ...you could perhaps open it up and go 1 click looser on the springing

whilst doing that measure the resistance of the wiper at closed throttle
or even better ...apply voltage to the system and read what voltage you are getting at closed afm

I found that a voltage of about 1.65 volts is about right for a static closed throttle from the afm .
the pc board that hold the resistance part of the mechanism can be moved slightly on its board mounts ...which can make a fair bit of difference

likewise the arm that sweeps the laser cut resistor board can be manipulated to read a different value on closed afm

there is a bolt arrangement that holds it all in place on an armature attached to the vane inside the afm ...

Fast Idle .... Latest: It is finally fixed! Air-fl10

note this is careful and critical adjustments required ...with maybe several attempts before getting it all right

would be wonderful to have an exhaust analyser for this type of work ..

bit detailed for the average ...but not impossible for the adventurous

please note   the sweep arm and contact point  through an armature and plate do happen to loose connection after vibrating around for years and years ...I have found at least one that was open circuit between the contacts intermittently ....I guess the result would look to be all sorts of weird fuel mixtures whilst riding

Fast Idle .... Latest: It is finally fixed! 2013-010

there is a fix...to install some very flexible cable (by soldering - crimping would be better ) a piece of cable between the  armature and the stator  parts of the mechanism  to eliminate the issue


__________________________________________________
cheezy grin whilst riding, kinda bloke ....oh the joy !!!! ...... ( brick aviator )

'86 K100 RT..#0090401 ..."Gerty" ( Gertrude Von Clickandshift ) --------O%OFast Idle .... Latest: It is finally fixed! Au-log10

'86 k100 rs.. #######..  "Fred " (f(rame) red ) ( Fredrick leichtundschnell ) - -
bits and pieces from many kind friends across the k100 world ...with many thanks ..
    

Kafflut

Kafflut
Silver member
Silver member
@charlie99 wrote:

whilst doing that measure the resistance of the wiper at closed throttle
or even better ...apply voltage to the system and read what voltage you are getting at closed afm

I found that a voltage of about 1.65 volts......

bit detailed for the average ...but not impossible for the adventurous

please note   the sweep arm and contact point  through an armature and plate do happen to loose connection after vibrating around for years and years ...I have found at least one that was open circuit between the contacts intermittently ....I guess the result would look to be all sorts of weird fuel mixtures whilst riding
Thank  you again, Charlie

It's a bit daunting for me, but I won't not do it - I'll take your comments and photos to my friend Bill who's a electronics engineer. If he can help me do it I may open that thing, the AFM

I hear your comments about bad connection and consequent erratic fuel mixture adjustments. Assuming there isn't a poor connection and assuming the mixture is too lean at the moment, would a workaround not be a small resistor in the wire to the FIU?

http://bmwk100k75.weebly.com/
    

charlie99

charlie99
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no defiantly not

in the mix of the signals sent from the afm to the icu  is a temperature sensor in the throat of the afm  which compensates for temperature changes etc which has some interaction with the wiper signals . 

by all means take the afm to a knowledgeable technician  for the repair - inspection 

the wiring fix across the junction of the  wiper and armature ...is a revised, at a later stage, factory implementation
plus there are heaps of online recommendations  for the exact same repair - upgrade from all sorts of "bosch  le " systems  in all kinds of applications

good luck


__________________________________________________
cheezy grin whilst riding, kinda bloke ....oh the joy !!!! ...... ( brick aviator )

'86 K100 RT..#0090401 ..."Gerty" ( Gertrude Von Clickandshift ) --------O%OFast Idle .... Latest: It is finally fixed! Au-log10

'86 k100 rs.. #######..  "Fred " (f(rame) red ) ( Fredrick leichtundschnell ) - -
bits and pieces from many kind friends across the k100 world ...with many thanks ..
    

47Back to top Go down   Fast Idle .... Latest: It is finally fixed! Empty Idle Mon Oct 31, 2016 4:05 am

Kafflut

Kafflut
Silver member
Silver member
Hello again, Charlie, and thanks for your previous input

I did a lot of what you suggested before. I now have a reasonable system Very Happy I can adjust the idle rpm down to near stall at +/- 750 rpm. Of course I don't do that, I have it at about 1000

What happens now is a miss. At cold it idles smoothly, but when warm it will miss a beat now and then, say 3 or 4 times a minute. When that happens the instrument panel lights e.g. neutral indicator light also go off for a split second. It's like there's no electricity in the whole system for that fraction of a second. Sometimes it's just a flicker. I don't see it at higher revs, say 1500 rpm and higher, but that may be because one can't see it at that speed.

I checked coils. I have a new battery. I checked earth contact points. New fuel filter. Fuel pressure at the rail is okay.

Do you have suggestions?

Does anybody have suggestions?

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TacKler

TacKler
Life time member
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I'll let the 'lecky experts answer this but it may be the ignition switch requiring a clean of the internal contacts.  I believe there was a link to this recently.

Possibly also the RH handlebar ON/OFF switch being worn?


__________________________________________________
Red 1991 K75S
    

Kafflut

Kafflut
Silver member
Silver member
Thanks, Tackler. I'll bypass both - make sure it's not either of those before I scratch further.

http://bmwk100k75.weebly.com/
    

Point-Seven-five

Point-Seven-five
Life time member
Life time member
The ignition switch is a good thing to check.  I had much trouble with mine last year on a bike that had always been garaged and was in otherwise pristine condition. 

I suspect that the problem is due to a design that puts very little contact force on the internal electrical contacts, making them somewhat sensitive to the slightest bit of dirt or corrosion. 

I suspect the reason you see it more at low rpm's is that the vibration of the engine is less as the rpm's increase, shaking the switch internals less.  As the problem progresses you will have the pleasure of having the electrical system shut down momentarily, usually on the highway at speed, which is what finally convinced me to go in and clean the switch.


__________________________________________________
Present:
1994 K75RT
1991 K100RS
1988 K100RS SE

Past:
1994 BMW K75S
1992 BMW K100RS
1982 Honda FT500
1979 Honda XR185
1977 Honda XL125
1974 Honda XL125
1972 OSSA Pioneer 250
1968 Kawasaki 175
    

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