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1Back to top Go down   Low MPG (KPL for you guys across the pond) Empty Low MPG (KPL for you guys across the pond) on Sun May 03, 2020 11:57 am

zaubertuba

zaubertuba
Silver member
Silver member
So in recent years I let my "good habit" of tracking milage at each fillup lapse.  Just recently I started back up but didn't bother to calculate my mpg from each fillup.  

I sat down last night with my phone calculator and filled in the blanks.  Turns out I'm averaging 25 mpg city driving and 30 mpg highway.

I should be expecting better, right?  Nothing seems off in the sound/exhaust/performance of the bike.  Maybe it's time to send my injectors up to Mr Injector up in N. Idaho?



Last edited by zaubertuba on Fri May 08, 2020 12:59 am; edited 1 time in total

    

Laitch

Laitch
Life time member
Life time member
@zaubertuba wrote:Turns out I'm averaging 25 mpg city driving and 30 mpg highway.  I should be expecting better, right? 
I've read through your previous posts and there is nothing that indicates you have cleaned the air filter, replaced the spark plugs, measured the valve clearances and balanced the throttle bodies—the condition of those components have a bearing on fuel economy.

Would you bring us up to date?


__________________________________________________
1995 K75 73,000 miles
Low MPG (KPL for you guys across the pond) Usa-lo10
    

zaubertuba

zaubertuba
Silver member
Silver member
I did the filter, plugs, deoxed all the electrical connections I could reach (particularly those in the ignition path), replaced a lot of rubber, and early on did check for leaks in the throttle bodies.

Though, I did a lot of that work when I first got the bike and had everything apart doing the deep drivetrain stuff. The air filter's probably still good but I can check it again, and I probably should check my plugs, as well. Embarassed

I have *not* checked valve clearances (my shop guy, on hearing the low mileage of the bike said I shouldn't mess with them yet), nor balanced the throttle bodies (I've been thinking a lot about this since it seems to come up a lot in talking about engine vibes).


__________________________________________________
1985 K100RS
    

Laitch

Laitch
Life time member
Life time member
@zaubertuba wrote: I have *not* checked valve clearances (my shop guy, on hearing the low mileage of the bike said I shouldn't mess with them yet), nor balanced the throttle bodies
30K miles is an appropriate stage to check clearance and balance throttle bodies.

It is unnecessary to "mess with" valve clearances in order to check them. All that's necessary is having the appropriate feeler gauges and the ability to remove and replace the cam cover without creating leaks, all of which is well within your ability.


__________________________________________________
1995 K75 73,000 miles
Low MPG (KPL for you guys across the pond) Usa-lo10
    

moriarti

moriarti
Silver member
Silver member
On those mpg figures it should be running like a bag of nails,sooty plugs overfueling and a strong smell of fuel.Either your calculations are wrong,someone is nicking your fuel, if any of the above don't apply, my thoughts are on the injectors
best of luck.I would have my own serviced rather than buy on  ebay if possible


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1984 k100 rs red/black VIN  0004449
    

Two Wheels Better

Two Wheels Better
Moderator
Moderator
@zaubertuba wrote:I did the filter, plugs, deoxed all the electrical connections I could reach (particularly those in the ignition path), replaced a lot of rubber, and early on did check for leaks in the throttle bodies.

Though, I did a lot of that work when I first got the bike and had everything apart doing the deep drivetrain stuff. The air filter's probably still good but I can check it again, and I probably should check my plugs, as well. Embarassed

I have *not* checked valve clearances (my shop guy, on hearing the low mileage of the bike said I shouldn't mess with them yet), nor balanced the throttle bodies (I've been thinking a lot about this since it seems to come up a lot in talking about engine vibes).
After everything else is checked and confirmed, you don't wanna be mucking round with attempting to 'balance' the TBs for road running as it is done with incremental turns of the air screws for engine idle only.


__________________________________________________

"It is a capital mistake to theorize before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts."

Arthur Conan Doyle
1970 R60/5, '77 R75/7-R100, '85 K100'87 K75C, '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  - all of the Beemers in my life I can recall, owned still or sold on.
    

Point-Seven-five

Point-Seven-five
Life time member
Life time member
I suspect your calculations are off.  If you were using that much fuel, after using one tank the plugs would be so fouled that there is no way the engine will start.

How are you measuring the miles?  I assume it's the tripmeter.  Does it skip or run slow?


__________________________________________________
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
    

zaubertuba

zaubertuba
Silver member
Silver member
@Point-Seven-five wrote:I suspect your calculations are off.  If you were using that much fuel, after using one tank the plugs would be so fouled that there is no way the engine will start.

How are you measuring the miles?  I assume it's the tripmeter.  Does it skip or run slow?

My tripmeter doesn't work so I'm using odometer mileage. I'm calculating using: (CurrentMileage-PreviousMileage)/AmountOfFuelAtPump.  I double-checked my math.

Gotta get ready for interviews so I didn't have time to check anything today.  I'll pull the plugs tomorrow night and have a look.  It *has* been harder starting, I noticed, this past week.


__________________________________________________
1985 K100RS
    

RicK G

RicK G
VIP
VIP
Hard to start it may be time to check the temp sensor. If it is faulty the ECU can think it is cold so makes the mixture rich and maybe lean at start because it may be giving the same reading hot or cold. There will be a write up Bert did about checking it.


__________________________________________________
"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 1993 K1100 LT, 1998 K1100 LT, 1993 K75 RT, 1996 K75RT, 1986 K75 GS, 1979 Z1300 Kawasaki X 2 for now
    

92KK 84WW Olaf

92KK 84WW Olaf
Life time member
Life time member
Vacuum caps and vacuum pipes to the fuel pressure regulator if faulty can do this. So can the Z pipe crank case vent.


__________________________________________________
1992 K100LT 0193214 Bertha Alaska 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 103,800 miles
1983 K100RS 0011171 Fricka 606 29,495 miles Damn K Pox Its a Bat outta Hell Now 36,188  miles
    

zaubertuba

zaubertuba
Silver member
Silver member
So a couple things:

Rick does this corroborate what you're thinking:  It was cold this morning. Bike would not start and after two tries wouldn't even turn over.  Took two more charges with my smart charger before I could get it to fire up (and stay running). In the afternoon when it was sunny and warm, and I had no problems whatsoever.

Possibly related: I forgot a while ago, I'd unplugged the TPS in attempting to troubleshoot a surging/stuttering issue.  I haven't had the issue since and never plugged the TPS back in. Embarassed 

Battery and Alternator:  Voltage at rest is 12.25 V. On idle it drops to around 11.8 V (no wonder that pesky batt light comes on at idle, lol).  Revving up it comes up to around 13.5 V, so seems the alternator is doing what it's supposed to do.

Spark plug condition--at least here's #1:
Low MPG (KPL for you guys across the pond) Plug10
That doesn't look like an overrich running condition to me. scratch Gap is at .034

I also let it idle this evening and sprayed some WD40 on the throttle bodies/rubber hoses and that didn't seem to effect a change of any sort, as far as looking for leaks (before I start yanking stuff apart, anyway).

Still in a quandary....


__________________________________________________
1985 K100RS
    

Point-Seven-five

Point-Seven-five
Life time member
Life time member
That spark plug makes it very hard to imagine how you are using that much fuel.

At 12.25v, the battery voltage is very low.  That can create issues with the injection system.


__________________________________________________
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
    

moriarti

moriarti
Silver member
Silver member
The hidden curse of the K. Battery must be well on top of the job,also 13.5v from alternator should be better,14v+well worth a look at the brushes etc .I have been 
caught out with a bad battery in the past easy missed. Embarassed


__________________________________________________
1984 k100 rs red/black VIN  0004449
    

volador

volador
Life time member
Life time member
Temp sensor on coolant 'T' into engine block ≅ 2.5KΩ @ 20°C

test pins 10 and 5 on the ECU connector plug under the seat. Flat blade screwdriver, 'lever forward' in the hole of the tooltray to loosen ECU connector plug

check the wires from Pin 10 & 5 of the fuel injection control unit plug for open or shorts

Pin 10 - violet/green
Pin 5- brown


__________________________________________________
1984 K100RS  1991 K100RS  Reap The Wild Wind... Ever Commute Is An Adventure
    

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