Another k100 stall question

[zprovo]

I realize this issue has come up, and I'm working my way through some (cheaper) solutions, but my symptoms seem slightly different than other posts.
My '85 K100rs with 56K miles began stalling two weeks ago (right after an oil change, coincidence?) It will usually stall after 6 miles or so on the highway coasting to a stop on the off ramp, it never stalls while running, just when the clutch is in coming to a stop. There is no trouble at all restarting the bike, it fires right up like nothing happened.
I'm assuming the oil change has nothing to do with it, but it's strange that the stalling started the very same day.
So far, I've cleaned the air filter, changed out the gas that was in it and checked the plugs.
My "to check" list includes, replacing the fuel filter, resistance in the plug wires, and finally hit the hall sensor with a hair dryer.
Anything else I should do or not do?
Thanks for your help / time.

[Bobmws]

Check the crankcase breather hose behind the throttle bodies, and the vacuum hose to the fuel pressure regulator, also the vacuum caps on the other 3 throttle bodies.

[deilenberger]

I realize this issue has come up, and I'm working my way through some (cheaper) solutions, but my symptoms seem slightly different than other posts.
My '85 K100rs with 56K miles began stalling two weeks ago (right after an oil change, coincidence?) It will usually stall after 6 miles or so on the highway coasting to a stop on the off ramp, it never stalls while running, just when the clutch is in coming to a stop. There is no trouble at all restarting the bike, it fires right up like nothing happened.
I'm assuming the oil change has nothing to do with it, but it's strange that the stalling started the very same day.
So far, I've cleaned the air filter, changed out the gas that was in it and checked the plugs.
My "to check" list includes, replacing the fuel filter, resistance in the plug wires, and finally hit the hall sensor with a hair dryer.
Anything else I should do or not do?
Thanks for your help / time.

I didn't see any mention of your idle speed. Below 1,000 RPM's a FYK100 will do this. Was the new oil higher viscosity than the old oil? That will make it worse.

Simple fix - up the idle to 1,100 RPM.

[zprovo]

fuel filter fixed it!
thanks for all the help! :thumb

[Brickhead]

Hey All,

Since we're on the subject, I am hoping you all can help me figure out this one...On my '85 K100RS, I started getting a stalling/bucking at highway speed, once in a while and very briefly, seemingly only when in 5th gear. When it first happened, I assumed I had a clog somewhere in the fuel system, topped off with new gas and that seemed to fix it. But it started happening again on a long trip this weekend...letting the bike slow down a bit, then downshifting seemed to temporarily fix it, and I was able to keep riding awhile...but by the time I pulled back into town on my return, it was doing it a lot, just running horribly and feeling really underpowered...

I've read the previous posts, but many of the stuff mentioned seems unlikely in my case, as I just had a full service last summer, including new sparks, spark wires, fuel filter, front and back splines, etc. But then last night as the problem was getting bad, I remembered that when i had the service done, they told me it was also high time i got a new clutch, which i declined (i was already way over budget, and it wasn't giving me any problems). But now I'm thinking - could it be a slipping clutch causing this problem? I don't have the dosh to stick it in the shop and start throwing hundred-dollar bills at it, and want to try every other possibilty before I try to replace the clutch - anyone out there ever have a clutch die on them? If so, I'd love to hear the story and list of symptoms to look for, and also whether it's possible for an amateur to replace it...Thanks for your time... :dunno

[roy]

Hey All,

Since we're on the subject, I am hoping you all can help me figure out this one...On my '85 K100RS, I started getting a stalling/bucking at highway speed, once in a while and very briefly, seemingly only when in 5th gear. When it first happened, I assumed I had a clog somewhere in the fuel system, topped off with new gas and that seemed to fix it. But it started happening again on a long trip this weekend...letting the bike slow down a bit, then downshifting seemed to temporarily fix it, and I was able to keep riding awhile...but by the time I pulled back into town on my return, it was doing it a lot, just running horribly and feeling really underpowered...

I've read the previous posts, but many of the stuff mentioned seems unlikely in my case, as I just had a full service last summer, including new sparks, spark wires, fuel filter, front and back splines, etc. But then last night as the problem was getting bad, I remembered that when i had the service done, they told me it was also high time i got a new clutch, which i declined (i was already way over budget, and it wasn't giving me any problems). But now I'm thinking - could it be a slipping clutch causing this problem? I don't have the dosh to stick it in the shop and start throwing hundred-dollar bills at it, and want to try every other possibilty before I try to replace the clutch - anyone out there ever have a clutch die on them? If so, I'd love to hear the story and list of symptoms to look for, and also whether it's possible for an amateur to replace it...Thanks for your time... :dunno


Hi Brickhead,

Typical slipping clutch symptoms:

1) Accelerating in in 4th or 5th gear the engine will rev up but the bike doesn't gain speed.

2) If dropping into 4th made it run better I doubt the problem is with the clutch.

3) Changing clutch depends on your mechanical skill level.

A Bad clutch will not cause an engine to miss or stall.

A couple of questions to help the members of this forum with diagnosis.

1) Does the bike run well at lower speeds or RPMs?

2) Do you have trouble accellerating from a stop?

3) Does it seem like the bike is misfiring on one or more cylinders?

Any extra syptoms will help.

Roy

[jdiaz]

Since we're on the subject, I am hoping you all can help me figure out this one...On my '85 K100RS, I started getting a stalling/bucking at highway speed, once in a while and very briefly, seemingly only when in 5th gear. When it first happened, I assumed I had a clog somewhere in the fuel system, topped off with new gas and that seemed to fix it. But it started happening again on a long trip this weekend...letting the bike slow down a bit, then downshifting seemed to temporarily fix it, and I was able to keep riding awhile...but by the time I pulled back into town on my return, it was doing it a lot, just running horribly and feeling really underpowered...

Check the spark plug caps. One of them has come loose (the rubber boot isn't gripping the plug solidly anymore) and is making intermittent contact. I bet if you push on all of them, you'll find one that will snap back on.

Coming back to this later....check the fuel pump connector! Those early connectors seem to have trouble maintaining a consistent connection.

[Brickhead]

Hi Brickhead,

Typical slipping clutch symptoms:

1) Accelerating in in 4th or 5th gear the engine will rev up but the bike doesn't gain speed.

2) If dropping into 4th made it run better I doubt the problem is with the clutch.

3) Changing clutch depends on your mechanical skill level.

A Bad clutch will not cause an engine to miss or stall.

A couple of questions to help the members of this forum with diagnosis.

1) Does the bike run well at lower speeds or RPMs?

2) Do you have trouble accellerating from a stop?

3) Does it seem like the bike is misfiring on one or more cylinders?

Any extra syptoms will help.

Roy


Hey Roy, all,

Yeah, the engine does seem to be stalling, as if fuel is suddenly being cut or some kind of ignition problem. Has only been happening consistently at higher speeds/rpms, and does not rev without pulling the bike, a big symptom of clutch slippage...It does sometimes spudder and run rough when taking off from a stop, and even stalled the other night trying to take off from a toll stop. Really hoping it's something simple, like loose spark wires or some such, but all the stuff done during the recent full service seems to rule out a lot of the obvious possibilities. REALLY hoping I'm just being paranoid about the clutch...

Thanks guys, I'll have a look this weekend and report back...Meantime, any other feedback is appreciated...

-Brodie

[roy]

Brodie, best advice, hope one of the real experts respond the ones that have been riding these bikes since they were made.

A couple of thoughts from the rookie.

1) Fuel filter may be plugged. When fuel tank is close to empty fairly easy to change. (Note: If like my 85K, watch out for the reinforcing bar in the tank it cuts like a razor)

2) From what you describe it sounds like something more serious than a loose plug wire. Maybe dirty ignition switch?

3) Look at the link below, their are some great articles of diagnosing and repairs.
http://www.ibmwr.org

4) Vacuum leak? look at the tube that goes from the rear intake filter box to the crank case. They age and crack.

5) Pray one or more of the experts respond.

Good luck random problems are a pain to find

Roy

[Brickhead]

Thanks guys for all the feedback - hopefully i'll have time to take look and start troubleshooting this weekend...jdiaz, i'lll be trying your solution first, but if it turns out to be as easy as pushing a spark plug wire home, i'll feel like a real jackass for living with the problem as long as I did!
:wave