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

[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? ;-)

 

[UncleMike]

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? ;-)

Nope, that's what I used to give it a vaccuum synch. Twice.

Explain that.

 

[t3rmin]

Nope, that's what I used to give it a vaccuum synch. Twice.

Explain that.

Ack. Um...

Well barring some kind of a problem with the vacuum gauge (cracks in tubes, uneven length hoses, poor seal on the intake tap spigot thingies, missing some of those little plastic "restrictors" in the hoses, etc.), or a vacuum leak(s) in the carbs/intakes (torn slider diaphragm, bad vac hose/petcock diaphragm, torn or improperly-seated intake boot, etc.), then either the throttle adjustment screws vibrated themselves out of sync (did you get those locknuts good and tight?), or something in the motor is out of whack (valve lash?). Or I guess we could still be dealing with clogged pilot circuits or something. When I clean the carbs and spray carb cleaner in the holes, then blow it out with a compressor, I like to see whether I can observe mist coming out of the teensiest passages (like the pilot holes in the carb throat near the top of the flapper and the tube thingy in the float bowls). Can you verify that mist does spray out of these tiny holes when you blow out the appropriate jets and such with a compressor?

I think the first thing I'd do before touching anything is put those carbs right back on and hook up the vacuum sync gauge again. You want to find out if the mercury levels still look correct when you *know* the flappers are out of whack or whether the carbs are simply out of sync again somehow (evidenced by the mercury levels being all over the place). Also, are you syncing at idle or a higher RPM?

 

[UncleMike]

Well, the locknuts are tight, so I know they didn't vibrate out of synch.

Brand new fuel and vaccuum lines, as well as brand new carb to engine and carb to airbox boots.

Petcock tests fine and all the diaphragms look perfect.

Guess I'll stick the damn carbs BACK on and check that synch.

Thanks,
Mike

 

[r.t.snake]

Hi,

If you do get to the bottom of things I would love to know because I went through the same scenario with my 82 550. I got pretty much the same advice about clean carbs, intake leaks, throttle cables, and spark, and finally just left the bike at the back of the shop and rode my Honda. Started it up today with a faint hope that yet another cleaning and new intake boots and o-rings would help but, alas, same old thing....


RT

 

[UncleMike]

Hi,

If you do get to the bottom of things I would love to know because I went through the same scenario with my 82 550. I got pretty much the same advice about clean carbs, intake leaks, throttle cables, and spark, and finally just left the bike at the back of the shop and rode my Honda. Started it up today with a faint hope that yet another cleaning and new intake boots and o-rings would help but, alas, same old thing....


RT

Well, that's encouraging,...*

 

[r.t.snake]

Actually Mike,

I got pretty close to a solution last spring with a suspect carb synk tool. That was just before I quit.( Well took a break from it)

If there is a faint hope, I would say that it might be with synchronization.

Good luck!

 

[t3rmin]

Hi,

If you do get to the bottom of things I would love to know because I went through the same scenario with my 82 550. I got pretty much the same advice about clean carbs, intake leaks, throttle cables, and spark, and finally just left the bike at the back of the shop and rode my Honda. Started it up today with a faint hope that yet another cleaning and new intake boots and o-rings would help but, alas, same old thing....


RT

I wonder if you took the carbs off and examined the throttle flappers at small openings, if they'd look uneven like Mike's?

 

[r.t.snake]

Not really, I just double checked them with a wire guage before I put them on yesterday, they all measured out evenly (?)

 

[t3rmin]

Not really, I just double checked them with a wire guage before I put them on yesterday, they all measured out evenly (?)

Hmm. Have you tried the "hold them up to light and observe the slivers" method?

It's a stinkin' sensitive adjustment, though, so who knows...

 

[Commodus]

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?

Well, there are always going to be differences - that's why we have to sync them in the first place.

I would certainly not expect those differences to be so large. This indicates excess cylinder differentiation (heh, look at me, I sound all technical) - I assume you've already checked compression and valve clearances, cuz there's no point in trying to sync a carb bank without checking yer valves.

If these check out, the carbs are not sealing. The ole "spray-em-with-WD40-til-you-kill-a-cylinder" trick should tell you where, and which.

It is also possible that the carbs are simply worn. How many miles are on this bike?

It would be very nice if someone with a working set of carbs was in your area and could try their set. Too much guesswork in this troubleshooting process right now.