I need help solving a gas mileage problem on my 1995 k75s.It has about 75,000miles on it.I have only been getting about 28-32 miles per gallon. I just purchased the bike but assume the mileage should be closer to 40-50.The dealership replaced the temp sensor,synced the throttlebody,and adj.the throttle butterfly switch.This has not improved my mileage.Also the bike will tend to die if you pull in the clutch and hold as you downshift.Any ideas on what could be the source of my problem?
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poor gas mileage on my k75
- Thread starter hawkon2
- Start date
burnszilla
New member
Change the air filter?
New spark plugs?
A valve job will help it run smoother.
I drive mine hard and get about 38 mpg.
My BMW mechanic told the to run the engine with high RPMs up to around 7 grand. The engine can take it and it likes it.
New spark plugs?
A valve job will help it run smoother.
I drive mine hard and get about 38 mpg.
My BMW mechanic told the to run the engine with high RPMs up to around 7 grand. The engine can take it and it likes it.
deilenberger
A bozo on the bus
Your fuel mileage on a K75 can range from 28-58 MPG in my experience.hawkon2 said:
All low speed around town riding - look for around 30MPG. Constant highway speeds (80 MPH indicated) - no stops, no slowdowns, no big hills - 45-50MPG. Flat highway riding as conservatively as you can stand (ie - constant 70MPH indicated) - you may get over 50.. Best I've ever gotten was 58MPG - and that was under those sort of conditions. No hills, constant (boring) 70MPH indicated (probably about 65 real MPH) - running from tank to tank.
The stalling is usually a sign the idle is set a bit low. What speed does the bike idle at? Although they will idle smoothly at around 600-800 RPM, 1,000 RPM is the actual specified speed IIRC, and it shouldn't stall when coming to a quick stop when set to 1,000 RPM idle.
Certainly worth doing a minor tuneup - plugs and perhaps a check of the valve clearances. The fuel filter and air filter will NOT cause low fuel mileage.. they can effect top speed capabilities, but the metering of the intake air compensates for any intake restriction, and a plugged fuel filter results in a lean condition - not rich.
The dealership may have replaced an unneeded part - it isn't hard to check if the temperature sensor is OK - an ohmmeter at the FI computer will tell that very quickly (see the IBMWR K-tech pages for details and specifications). A bad temperature sensor can cause a rich mixture - so they were thinking about what was going on..
Hopefully the "sync" of the throttle bodies was simply the idle-air-balance screws in the base of the TB's, and the throttle position switch really should never need adjustment once the linkage idle position is set correctly. The dealership was trying - but that isn't the route I would have taken.
Best,
johnnyquest
New member
hawkon2 said:
In addition to what Don said (and believe me, he's the expert) consider your fuel filter, air filter, and even your tire pressure. Changing the kind or viscosity of engine oil you use can also have an impact. Have you changed your gearbox and final drive oil lately? Also, have you purchased gas at different locations? What grade do you use? Lastly, one thing I use that others here may not recommend is a bit of Marvel Mystery oil in the tank. Every six or seven tanks I put a small amount in to help keep the injectors working smoothly.
JQ
hmmmm, my 87 T seems to have always been just the opposite: lower speeds have given the best mileage and interstates @80mph have produced the worst.
In my case most likely a result of the BM "International" windshield drag and also the BM Bosch aux. light set hanging out there.....?
In my case most likely a result of the BM "International" windshield drag and also the BM Bosch aux. light set hanging out there.....?
Thanks to all who have responded to my gas mileage problems.I have taken some of your advice but after replacing the plugs and adjusting the tire pressure I only got 30mpg on my ride today.It was mostly highway miles with speeds in the 70 to 80 range.Does anyone think that cool weather may be playing a role? The temp was about 55 degrees today.Please tell me That I really don't need to stop for gas every 100 miles.
deilenberger
A bozo on the bus
Something isn't right.hawkon2 said:
I did about 100 miles today - filled the tank when I left. My Fuel+ is telling me I have 93 miles left. Was a mixed ride of about 1/2 at 80MPH, the rest on secondary roads (30-50MPH) Fuel+ told me my average speed was 41MPH.
As Jon mentioned - although the K75 rarely ever needs a valve adjustment, it would be worthwhile checking the clearances. Cost is 2 rubber gaskets and you'll need a set of feeler gauges. The other possibility is it's running rich because one of the temperature sensors has gone belly up or the fuel pressure regulator has failed. Usually if the FPR fails - it barely runs.
Check valve clearances, check readings for the primary temperature sensor (instructions are probably in the K-tech section of www.ibmwr.org)
Best,
MOTORMAN
Retired and proud of it
One thing you might want to consider is a partially fouled injectoror two with that many miles on it. I'd run some good detergent fuel (Chevron) with some injector cleaner added to it as well. Go for about 1.5 to double the normal ratio of additive for one tank then normal ratio for a couple more tanks. Run it hard to get a good flow and for most of a tank if you can before shutting it down.
I had gummed up injectors from fuel that went bad. A BMW mech. told me about this possible fix for it and mine were so bad it would barely start and run with plenty of throttle added. After 3 tanks like that it cleared up and runs smooth with the old 40 to 44 MPG it had before.
Good luck!
I had gummed up injectors from fuel that went bad. A BMW mech. told me about this possible fix for it and mine were so bad it would barely start and run with plenty of throttle added. After 3 tanks like that it cleared up and runs smooth with the old 40 to 44 MPG it had before.
Good luck!
TomBarnhart
New member
K75 poor mileage
Valves, plugs, TB synch and one frequently missed item is the small rubber breather hose located behind some stuff near the coils. Replacement did wonders for mine. Also check the air filter and air box
Valves, plugs, TB synch and one frequently missed item is the small rubber breather hose located behind some stuff near the coils. Replacement did wonders for mine. Also check the air filter and air box
E
ERIC1514
Guest
How will you know the used one hasn't been messed with also? There must be some way to set them properly. Somebody at the factory did it once. But then again, I don't know what I'm talking about, either 
Good Luck,
Eric
Good Luck,
Eric
deilenberger
A bozo on the bus
I believe we've discussed this off line - and yes - that would be a good move if you can find one at a reasonable price. If it was me - I'd also replace any rubber bits that are disturbed during the installation - they aren't getting any younger and the parts aren't particularly expensive.hawkon2 said:
deilenberger
A bozo on the bus
They are adjusted and then the screws are painted over - or a protective cap was installed over the adjusting screws. If neither are in place - then that's one to avoid.Eric1514 said:How will you know the used one hasn't been messed with also? There must be some way to set them properly. Somebody at the factory did it once. But then again, I don't know what I'm talking about, either
Good Luck,
Eric
As far as setting them properly? If you have about $10,000 to spend on a precision flow bench it could be done - but doing it on the bike engine is NOT the way to do it - it simply misadjusts them to hide other problems (such as valve clearances, intake leaks, etc.)
Luckily since K75 engines are really inexpensive used ($300 or less will buy you a fine one) the TB's should also be equally inexpensive. I wouldn't expect to pay more than $100 for a good condition set, and probably less.
E
ERIC1514
Guest
deilenberger said:
And now I know!
As always, Thank You,
Eric
I seem to be on the right track.The mechanic does not have the precision flow bench in his shop-probably the 10000 price tag.I was able to pick up a throttle boby with tps for 100 bucks.If this solves my problem it would be a small price to pay.The seller insures me that the screws have not been tampered with-the paint is intact.
sheridesabeemer
I Used to Be Someone
deilenberger said:
Thought I'd recycle this rather than start a new thread. I was out all weekend on the K75 (70Kmi), I was experiencing real problems with the bike stalling when coming to a stop. At first it was intermittent then it was constant. I took to turning the "choke" on as I approached a light or stop sign. This would keep the revs over 1K and prevent the stall. Scary stuff having the bike stall as you do a slow U-turn on Main street to get a parking space!
Without the choke on, the revs are maybe 800, sounds like it's about to die as if the engine where cold. My riding companion thought that low revs where a symptom of something else. I last had major (non-dealer) service done last June (6K miles ago). The spark plugs where changed as well as fuel filter, fuel line, and crankcase breather hose. I changed the air filter last month.
Any ideas why this has cropped up? Could there be a relation to my putting lower grade fuel in it lately?
Hi, Gail,
Harriet has had 3 K75's - a '95 K75RT (now with her brother), a '95 K75 (now with Paul Glaves as Smokey II) and a '94 K75A/3 which she rides, when she rides. When we're together and I fill my K1100LT with premium, she sometimes fills the K75 from the same pump on the same credit card swipe. All other times the K75 gets a steady diet of regular unleaded, 86 (pump) octane where we live, and it hasn't complaind at all. The book says 91ROZ, which means 91 octane (research method), e.g., REGULAR, leaded or unleaded.
Harriet has had 3 K75's - a '95 K75RT (now with her brother), a '95 K75 (now with Paul Glaves as Smokey II) and a '94 K75A/3 which she rides, when she rides. When we're together and I fill my K1100LT with premium, she sometimes fills the K75 from the same pump on the same credit card swipe. All other times the K75 gets a steady diet of regular unleaded, 86 (pump) octane where we live, and it hasn't complaind at all. The book says 91ROZ, which means 91 octane (research method), e.g., REGULAR, leaded or unleaded.
My K100RT has just returned to getting respectable mileage. For a while, I was getting only 500 km to a set of plugs. Turns out the fuel mixture was too rich. Now that the fuel pressure regulator has been replaced, I am back to 50+ mpg (Canadian gallon). That certainly beats the 140 km to the tank prior to this repair.
