Still Won't Idle! I think I'm done.

[UncleMike]

Well, they're mounted! New coils, new wires, new caps. Getting 11.7v at the coils or more, and getting a 25K secondary resistance reading now.

The bike is now 100%, without a doubt, unmistakeably,...










...ABSOLUTELY THE FRICKIN' SAME!

No change, whatsoever. This is depressing as all hell. I don't know what else to do.

Here's a nice little re-cap:

The bike will start very quickly with full choke and idle at 900rpms. The rpms will then start to climb and reach around 2900rpms and stay there for about ten seconds, at which point the rpms will begin to fall until the bike stalls. No amount of messing with the choke will prevent her from stalling.

If I walk away for about 2 minutes or so and then attempt to start it again, she'll start right away with no choke and idle at 1100rpms, albeit not very strongly.

Now, when she's beginning to stall, I can prevent it by giving her light throttle and holding the throttle on for about a minute or two, at which point she'll idle on her own with no choke. But again, it's not confidence-inspiringly strong.

When riding, if I pull in the clutch and hold it, she'll often stall out on me. More often than not, actually, until I get her warmed up.

When she's FULLY warm, her idle jumps about 800rpms to 2000.

Things I've done:

Cleaned and rebuilt the carbs. New o-rings and gaskets. All floats set to 22.5mm.

Replaced the R/R with a Honda, charging numbers are spot-on.

New sealed battery.

Bandit coils, Accel wires, new NGK caps.

All new filters and plugs.

Cleaned connections.

None of the above changed things in the least.

Please guys,...please. It's a year today since I got the bike and I'm starting to get a little frustrated.

~Mike

 

[Commodus]

Very frustrating, I can relate. I recently had a similar situation with my old Katana, which I resolved by buying a set of RS carbs.

If the carbs are sealing properly, and the coils and whatnot are doing their job (and obviously a dirty air filter isn't going to cause this), I wonder if a borked CDI box could cause this problem.

I don't have the testing specs (though I'm sure they're in any service manual), but I would suggest you go there next.

Good luck! It's good to have hard problems, they teach you the most.

 

[Pharkmeh]

are you SURE its not a harley.....:-s

 

[Steve]

Mike, you stated in your post...

"Cleaned and rebuilt the carbs. New o-rings and gaskets."

Does this include the o-rings between the intake runners and the cylinder head? Your symptoms are rather classic of a leak at this site. You can check by spraying something like WD-40 around the joint area while the bike is running. If the idle speed changes, the WD is sealing the leak, allowing a proper mixture. I don't remember who it is, but someone here on the board has these o-rings for a decent price if you can't get them from your dealer.

After changing the o-rings, don't forget to go back and re-set the idle mixture screws for best idle.


.

 

[UncleMike]

Mike, you stated in your post...

"Cleaned and rebuilt the carbs. New o-rings and gaskets."

Does this include the o-rings between the intake runners and the cylinder head? Your symptoms are rather classic of a leak at this site. You can check by spraying something like WD-40 around the joint area while the bike is running. If the idle speed changes, the WD is sealing the leak, allowing a proper mixture. I don't remember who it is, but someone here on the board has these o-rings for a decent price if you can't get them from your dealer.

After changing the o-rings, don't forget to go back and re-set the idle mixture screws for best idle.


.

It's a 16v engine, so it doesn't have those o-rings. I did, however, replace all eight carb boots, and did a vaccuum synch afterward.

Thanks,
Mike

 

[UncleMike]

Very frustrating, I can relate. I recently had a similar situation with my old Katana, which I resolved by buying a set of RS carbs.

If the carbs are sealing properly, and the coils and whatnot are doing their job (and obviously a dirty air filter isn't going to cause this), I wonder if a borked CDI box could cause this problem.

I don't have the testing specs (though I'm sure they're in any service manual), but I would suggest you go there next.

Good luck! It's good to have hard problems, they teach you the most.

I agree, and it is good that I'm learning something new at every step, but man I just want to ride!

How would one go about testing the CDI box?

Thanks,
~Mike

 

[bwringer]

Everything still points to an intake leak or plugged (or totally incorrect) idle jets and passages.

Lots of carb kits have incorrect jets -- this totally drove me nuts a few years ago until I figured out what was going on and cleaned and reinstalled the original jets.

Dig into the carbs and re-clean and re-verify EVERYTHING.

 

[Thomas Kenny]

Just for the heck of it try adjusting your throttle cable(s) at the twist grip and at the carbs. I had some idle problems after a cold start and fiddled witht the throttle cable adjustment. Not sure what I did :-D but it seemed to help the transition from choke idle to off choke idle.

Just a shot in the dark........

 

[DimitriT]

Still looks like some combination of carb problems. Do all the cylinders warm up evenly when its running? Are the plugs fouled up when it dies?

I'm still thinking you have a problem with the choke circuit. When you cleaned the carbs did you pay special attention to the choke jet pressed into the bowl? Make sure thats nice and clean (shoot carb cleaner into it from both sides). If those are mostly plugged you will get a working choke for a bit and then it will stop as it will need to refill at a slow rate. It sounds like the choke is working when it fires up initially but then runs dry.

The other problem you seem to have looks like something is still not right with the idle circuit. There are some narrow passages in there which need to get cleaned out and a few places where these branch. I will shoot cleaner into as many of these as I can (wear safety goggles) and hold my finger over the some to get cleaner into the passages under pressure. Pay special attention to the idle passages at the top of the intake passage. Use a fine wire and then shoot carb cleaner at them (you may have to remove parts to get a good shot).

When the carbs are properly cleaned and you have no vacume leaks you should be able to tune the idle very easily with the idle micture screws and the idle throttle knob.

If you were in the area I'd suggest you come over and we could try the carbs on my bike.

 

[mark]

Dig into the carbs and re-clean and re-verify EVERYTHING.

That seems right to me too. Maybe this doesn't help, but here's a short story. For the better part of a year, I couldn't get my Craftsman lawn mower to run right. It would start, run for about 30 seconds and then quit. So I'd clean the carbs out (took about 10 minutes) and then it would run great. Next time I started it the same #$mn thing.

I"ll bet I cleaned those mower carbs 15 times. One time I did it AGAIN....and it ran great and hasn't had a problem since. Somewhere I missed something....and to this day I don't know what it is.

 

[DanTheMan]

Mike, here's something to look at and try (again, due to a Craftsman lawn tractor). It'd run great, then wouldn't run without choke, and not well. I opened the carb, had to do this twice, I'd installed new fuel lines and everything, turned out both times I had to do this so it would run right, there was a little sliver of fuel line hose in the float valve, wouldn't allow fuel past.
Now, I wouldn't expect something like that to affect all four carbs, but maybe it could effectively clog the inlet passage to the carbs? Just a thoght, something to look at again.........

 

[UncleMike]

Okay,...I'll check the mfing carbs again.

Not what I wanted to hear, I was hoping more for a "snowman with his hat blown off" situation. "There you go little buddy!" And it's all better,...

...alas, it's not to be.

Anyway, thanks for taking yet another look at my hell and giving opinions. I'll keep you all updated.

Thanks,
~Mike

 

[Nessism]

I agree with the others that it's most likley a carb problem. Not sure what to suggest though other than getting inside and varifying everything is clean and sealed. I've heard the same thing regarding some of those aftermarket carb kits. I ordered carb parts direct from Bike Bandit for mine.

Sorry for all these problems. Don't give up.

 

[DanTheMan]

Hey, Mike, one more idea from another thread, check out your petcock from the tank and make sure it's working properly. It could even be your whole problem......

 

[UncleMike]

Hey, Mike, one more idea from another thread, check out your petcock from the tank and make sure it's working properly. It could even be your whole problem......

Yup, it passed the vaccuum test both this spring and about two weeks ago.

I hope you all realize I'm not being short with my answers. I do appreciate anyone who's still willing to contribute to this insanity.

~Mike

 

[t3rmin]

Well in the off-chance it is still ignition-related you could get a Dyna S. It's an upgrade you'll be glad you did anyway. At $120 it's not quite cheap (but not really super expensive either), but I still think of it as "cheap insurance" since it's better than getting stuck on the road somewhere and/or wasting hours of time t-shooting and second-guessing the crappy stock ignition. Can you put a price on piece-of-mind? ;-)

One last thing, have you checked the carb balance beyond a bench sync? I did what I *thought* was a pretty good bench sync the other day but when I put it back together I had one completely cold cylinder (flapper wasn't even open at idle in that carb) and a crappy idle and off-idle. Vacuum carb sync cleared that up 100%. If you had a combination of poor sync and maybe rich float and/or mixture screws, I could see that causing crappy idling or dying.

Have you seen this page? I found it on these forums the other day and it's fantastic:
http://www.factorypro.com/tech_tuning_procedures/tuning_carbtune,CV,high_rpm_engines.html

 

[bonanzadave]

Ill go along with Dan and say Fuel Supply. Check your main fuel line and your petcock vacuum line. Both ends. If you have not changed those hoses get some new hoses and clamp each end. If your sucking air.........Then your sucking air.

 

[UncleMike]

Ill go along with Dan and say Fuel Supply. Check your main fuel line and your petcock vacuum line. Both ends. If you have not changed those hoses get some new hoses and clamp each end. If your sucking air.........Then your sucking air.

I have new hoses on both, but have not clamped the vaccuum line. It wasn't clamped to begin with. In fact, none of my GS's have had their vaccuum lines clamped.

 

[t3rmin]

One more question: when you slowly rev it off-idle is it rough like there isn't fire on one or more cylinders? If so, try yanking the plug wires off the plugs one at a time and see if there's one cyl where, when there's no spark, the idle changes very little or not at all. Then you've identified your problem cylinder(s).

 

[UncleMike]

One more question: when you slowly rev it off-idle is it rough like there isn't fire on one or more cylinders? If so, try yanking the plug wires off the plugs one at a time and see if there's one cyl where, when there's no spark, the idle changes very little or not at all. Then you've identified your problem cylinder(s).

I haven't noticed that, no.