BMW K bikes (Bricks)

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1Back to top Go down   Idle & Sounds Empty Idle & Sounds on Thu May 24, 2018 7:25 am

George_Pap

George_Pap
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Hi all.
After the recent problem i had with the clogged fuel tank vent pipe bike now is back on the road. Put about 150km on it and in general it seems ok.
The only problem i face, since i m totally noob in K bikes is its idle behaviour.
Bike needs more than 5 minutes with the choke on and on the very start actually needs the second scale of the choke lever. For 3-4 minutes. After that period engine needs another 4-5 minutes on the first choke scale and  stabilises its rpm to 1000-1100 a noise is heard from the engine - crankcase (?)
Since a video will give you the picture i would like your experience on this.

Thank you.




Last edited by George_Pap on Thu May 24, 2018 7:36 am; edited 1 time in total


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K100RT (Early 1985 -nonABS)
    

2Back to top Go down   Idle & Sounds Empty Re: Idle & Sounds on Thu May 24, 2018 7:28 am

George_Pap

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at 00:41 you can hear exactly the  sound that worries me. It goes away after 10 minutes warm up. 
After that 10 minutes of the engine working idle sets to steady 1100 rpm and that noise is barely audible.


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K100RT (Early 1985 -nonABS)
    

3Back to top Go down   Idle & Sounds Empty Re: Idle & Sounds on Thu May 24, 2018 7:46 am

Dai

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Diesel knock! Very Happy I think we've all had that at some point - search the forum for lots of possible answers. The most likely causes are:

1. Dirty injectors
2. Air leak on the inlet stubs
3. Unbalanced throttle bodies.

If the RPM stabilises at 1100, I'd be inclined towards the air leak theory initially because idle RPM is 960-980 according to BMW. It's not something that will do any damage as it's (only) a misfire.


__________________________________________________
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
    

4Back to top Go down   Idle & Sounds Empty Re: Idle & Sounds on Thu May 24, 2018 7:56 am

George_Pap

George_Pap
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@Dai wrote:Diesel knock! Very Happy I think we've all had that at some point - search the forum for lots of possible answers. The most likely causes are:

1. Dirty injectors
2. Air leak on the inlet stubs
3. Unbalanced throttle bodies.

If the RPM stabilises at 1100, I'd be inclined towards the air leak theory initially because idle RPM is 960-980 according to BMW. It's not something that will do any damage as it's (only) a misfire.
Hey Dai! 

I've read almost everything Smile But reading finally made me terrify! Monkey nuts, Crankshaft pivots, Cam chain, Tensioners, even thermostat problems. 
God, i m more confused than ever !
Thats why i've posted the sound, hopping somebody to respond " Yes!!! Its the X thing, had the same sound! "

Which places are prone to air leak so to search?By inlet stubs, you mean the four rubber hoses that go into the throttle bodies? Have in mind that this sound became worse after patching the leaking crankcase breather hose !


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K100RT (Early 1985 -nonABS)
    

5Back to top Go down   Idle & Sounds Empty Re: Idle & Sounds on Thu May 24, 2018 9:04 am

Dai

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The four inlet stubs under the throttle bodies that bolt to the crankcase. Spray some WD40 (or similar) around them when the engine is running. If the RPM suddenly goes up and the knocking stops, you've found the air leak.


__________________________________________________
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
    

6Back to top Go down   Idle & Sounds Empty Re: Idle & Sounds on Thu May 24, 2018 10:28 am

duck

duck
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FYI: WD-40 is no longer as flammable as it used to be.  It still says flammable on the can but apparently the safety Nazis got to them so it is no longer as fun as it used to be. (Made great blow torches with dad's when I was a kid.)


__________________________________________________
Current stable:
86 Custom K100 (standard fairing, K75 Belly pan, Ceramic chromed engine covers, paralever)
K75 Frankenbrick (Paralever, K11 front end, hybrid ABS, K1100RS fairing, radial tires)
86 K75C Turbo w/ paralever
94 K1100RS
93 K1100LT (x2)
91 K1
93 K75S (K11 front end)
91 K75S (K1 front end)
14 Yamaha WR250R
98 Taxi Cab K1200RS
14 K1600GT
http://www.ClassicKBikes.com
    

7Back to top Go down   Idle & Sounds Empty Re: Idle & Sounds on Thu May 24, 2018 10:33 am

George_Pap

George_Pap
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@Dai wrote:The four inlet stubs under the throttle bodies that bolt to the crankcase. Spray some WD40 (or similar) around them when the engine is running. If the RPM suddenly goes up and the knocking stops, you've found the air leak.

will blow some butane gas with my flame torch ( Dremmel ). Guess will do. Smile


__________________________________________________
K100RT (Early 1985 -nonABS)
    

8Back to top Go down   Idle & Sounds Empty Re: Idle & Sounds on Thu May 24, 2018 10:33 am

George_Pap

George_Pap
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@duck wrote:FYI: WD-40 is no longer as flammable as it used to be.  It still says flammable on the can but apparently the safety Nazis got to them so it is no longer as fun as it used to be. (Made great blow torches with dad's when I was a kid.)

thank you! i second that!


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K100RT (Early 1985 -nonABS)
    

9Back to top Go down   Idle & Sounds Empty Re: Idle & Sounds on Thu May 24, 2018 11:33 am

Two Wheels Better

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What's the condition of the S-shaped hose which you can see near the throttle position sensor, which goes from engine to bottom corner of the airbox? In the brief flash of it in your video it looked like it had been taped up. Any cracks causing leaks will make the idle sound like a box of rocks. One quick way to eliminate the engine breather or vent hose as a source of poor idle/performance is to unscrew the engine oil filler cap on the right hand side whilst idling and note the significant idle drop. If the idle does drop further the hose is likely not a cause.

I use a propane torch with a very, very small stream of gas (not lit, of course), to determine air leaks at the throttle body rubber mounts.


__________________________________________________

“Some people see things that are and ask, ‘Why?’. Some people dream of things that never were and ask, ‘Why not?’. Some people have to go to work...

~George Carlin

1970 R60/5, OZ '77 R75/7-R100, '85 K100'87 K75C, OZ '87 K100RS, '93 K11-K12 Big Block, '93 K1100RS, '95 R100-Mystic, '96 K1100RS, '98 K1200RS, '00 K1200RS, '02 K1200RS, '03 K1200GT, '04 R1150R'04 R1150RT, '05 K1200S, '06 K1200R, '07 K1200R, '09 K1300GT & 2013 R1200RT-Polizei  - Beemers owned still or sold.

    

10Back to top Go down   Idle & Sounds Empty Re: Idle & Sounds on Thu May 24, 2018 11:57 am

George_Pap

George_Pap
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@Two Wheels Better wrote: If the idle does drop further the hose is likely not a cause.

Thank you. I have already checked that S hose. It's the crankcase breather hose as described in clymers . Found out It was cracked at the end that goes into the air box and as you correctly noticed I patched it with a fair amount of soft electrical tape till I receive the original .
Do you think that it might still be leaking? I mean is the pressure too high there?


__________________________________________________
K100RT (Early 1985 -nonABS)
    

11Back to top Go down   Idle & Sounds Empty Re: Idle & Sounds on Thu May 24, 2018 12:02 pm

Two Wheels Better

Two Wheels Better
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@George_Pap wrote:
@Two Wheels Better wrote: If the idle does drop further the hose is likely not a cause.

Thank you. I have already checked that S hose. It's the crankcase breather hose as described in clymers . Found out It was cracked at the end that goes into the air box and as you correctly noticed I patched it with a fair amount of soft electrical tape till I receive the original .
Do you think that it might still be leaking? I mean is the pressure too high there?
It's a chance. Pop off the oil filler cap and you'll know.


__________________________________________________

“Some people see things that are and ask, ‘Why?’. Some people dream of things that never were and ask, ‘Why not?’. Some people have to go to work...

~George Carlin

1970 R60/5, OZ '77 R75/7-R100, '85 K100'87 K75C, OZ '87 K100RS, '93 K11-K12 Big Block, '93 K1100RS, '95 R100-Mystic, '96 K1100RS, '98 K1200RS, '00 K1200RS, '02 K1200RS, '03 K1200GT, '04 R1150R'04 R1150RT, '05 K1200S, '06 K1200R, '07 K1200R, '09 K1300GT & 2013 R1200RT-Polizei  - Beemers owned still or sold.

    

12Back to top Go down   Idle & Sounds Empty Re: Idle & Sounds on Thu May 24, 2018 12:07 pm

George_Pap

George_Pap
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Read that in a post and did that test already .Engine stalls and almost goes out.


__________________________________________________
K100RT (Early 1985 -nonABS)
    

13Back to top Go down   Idle & Sounds Empty Re: Idle & Sounds on Thu Oct 22, 2020 1:06 pm

stanthomas

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@Two Wheels Better wrote:... poor idle/performance is to unscrew the engine oil filler cap on the right hand side whilst idling and note the significant idle drop. If the idle does drop further the hose is likely not a cause.
Can I ask, does this apply to K100 16V? On mine, removing the oil filler cap makes no difference at all to idle speed (or anything else). If everything is as it should be, what would you observe when the filler cap is removed?

    

14Back to top Go down   Idle & Sounds Empty Re: Idle & Sounds on Thu Oct 22, 2020 4:40 pm

92KK 84WW Olaf

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@stanthomas wrote:
@Two Wheels Better wrote:... poor idle/performance is to unscrew the engine oil filler cap on the right hand side whilst idling and note the significant idle drop. If the idle does drop further the hose is likely not a cause.
Can I ask, does this apply to K100 16V? On mine, removing the oil filler cap makes no difference at all to idle speed (or anything else). If everything is as it should be, what would you observe when the filler cap is removed?
If nothing changes then you need to look at the crank case breather pipe and vacuum pipes. It means some or all of them are goosed. This is a very cheap repair but slightly fiddly.


__________________________________________________
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.
    

15Back to top Go down   Idle & Sounds Empty Re: Idle & Sounds on Wed Nov 25, 2020 7:47 pm

stanthomas

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@92KK 84WW Olaf wrote:
@stanthomas wrote:
@Two Wheels Better wrote:... poor idle/performance is to unscrew the engine oil filler cap on the right hand side whilst idling and note the significant idle drop
Can I ask, does this apply to K100 16V? On mine, removing the oil filler cap makes no difference at all to idle speed
If nothing changes then you need to look at the crank case breather pipe and vacuum pipes. It means some or all of them are goosed. This is a very cheap repair but slightly fiddly.
The crankcase breather being the Z-pipe that everyone talks about?
Mine looks fine but I have a question about a motronic 16V. How does a leak in the crankcase breather affect the air flow? The breather vents into the airbox, downstream of the filter but upstream of the throttle bodies. Since there's no air flow sensor and the airbox is, in effect, open to the air, how can an air leak here affect the idle?

    

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