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

[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.

[t3rmin]

Well I'd probably still try the yanking the wires thing and see if the result is the same on all cyls.

[UncleMike]

Well I'd probably still try the yanking the wires thing and see if the result is the same on all cyls.

Would I get the same result from a compression test?

[Can_O_Tuna]

Mike...I wish I had a magic wand for you buddy. I have to give you credit for keeping at it this long....

I just met a guy the other day who is an ex-military mechanic. I have had some gremlins in my '92 Accord and he looked at it today and diagnosed it in about 30 seconds.....


If you spring for gas and beer, maybe I can come up and we'll haul the @$@$#%!^!& thing back here and I bet this guy can straighen you up. That and Hector's, which is our local stealer ummm dealer has a real oldtimer as their head guy and at this point I bet you might be so over it that you would be happy to just pay for a couple of hours of time from an expert. 8-[

[UncleMike]

Mike...I wish I had a magic wand for you buddy. I have to give you credit for keeping at it this long....

I just met a guy the other day who is an ex-military mechanic. I have had some gremlins in my '92 Accord and he looked at it today and diagnosed it in about 30 seconds.....


If you spring for gas and beer, maybe I can come up and we'll haul the @$@$#%!^!& thing back here and I bet this guy can straighen you up. That and Hector's, which is our local stealer ummm dealer has a real oldtimer as their head guy and at this point I bet you might just pay for a couple of hours of time from an expert. 8-[

I'll get it eventually. I promise. I hope. If not, I'll ride it over to your place. This stupid little problem may be annoying, but it hasn't stopped me from putting almost 3K on her so far this year.

[t3rmin]

Would I get the same result from a compression test?

Nope. Say you had a vacuum leak on #2 (like I did a while ago) and the mixture was so far off it was hardly burning at all. Pulling the wires (well, boots really) off the plugs one-by-one would result in little or no change in idle when you got to #2, since it wasn't burning much anyway. Then you'd know "looks like it's #2, I'll concentrate my efforts there", and you'd be that much closer to figuring it out.

Of course your problem may not be anything like that, but it's definitely a quick and easy test that I'd do!

[UncleMike]

Nope. Say you had a vacuum leak on #2 (like I did a while ago) and the mixture was so far off it was hardly burning at all. Pulling the wires (well, boots really) off the plugs one-by-one would result in little or no change in idle when you got to #2, since it wasn't burning much anyway. Then you'd know "looks like it's #2, I'll concentrate my efforts there", and you'd be that much closer to figuring it out.

Of course your problem may not be anything like that, but it's definitely a quick and easy test that I'd do!

I get it now. Thank you. Although, it's not that easy when the bike won't idle!

[t3rmin]

I get it now. Thank you. Although, it's not that easy when the bike won't idle!

You have a point there. ;-) Maybe turn your idle screw up a bit. The closer to idle the better, though, 'cause it's easier to hear roughness at lower RPMs (IMHO).

[UncleMike]

You have a point there. ;-) Maybe turn your idle screw up a bit. The closer to idle the better, though, 'cause it's easier to hear roughness at lower RPMs (IMHO).

Indeed. She'll idle when fully warm, but then she's not "doing it" at that point, so it'd be kinda hard to diagnose, you know?

[UncleMike]

So, I pulled the carbs because honestly, what else am I gonna do on a rainy Friday afternoon besides clean my carbs for the umpteenth time while watching Frankenstein Meets the Wolfman?

Anyway, I held the rack up to the light, and even though I JUST did a carb synch, butterflies #1 and 2 are open much more than #3 and 4. I can see a nice big sliver of light beneath 1 and 2, but almost nothing beneath 3 and 4.

So that would indicate?

[t3rmin]

There ya go! Remember my anecdote about the "good" bench sync I did the other day which still resulted in one flapper being totally closed at idle? I have a new understanding for the sensitivity of the sync adjustments after that incident. At idle those flappers are supposed to be nearly closed anyway, and having one or two even a *tiny* bit off can mean they are basically blocked at the lowest throttle openings. That could easily account for the symptoms you've described.

Anyway, I bought one of those mercury vacuum sync gauge quartets (Motion Pro brand) off eBay for $40 and I will *never* rely on anything less now (if I want a bike that actually idles). Sounds like that's your next purchase as well? ;-)