Rebuilt/Dipped carbs with jet kit but bike won't start.

[ironsheik]

So I can't get the bike to start and just wanted a few pointers on where to look. It's a gs1100ed with the stock airbox/K&N filter and yoshi 4-1. It ran well before besides a hesitation at 6k rpm but since I was rejetting with a dynojet stage 1 I had RenoBruce dip and paint my stock CV carbs. I drilled the slides as per the Dynojet instructions. Did a bench sync and replaced all the o-rings. The intake rubber is all nice and squishy still too. I'm getting fuel and spark but it seems like the plugs are a bit wet when I pull them. It just about starts but stalls out after half a second. Could it be floats? I didn't touch them except to replace the seat o-rings. I'm new to CVs so any tips would be greatly appreciated.

 

[TheCafeKid]

Anytime you pull the floats you should double check they are set right. Also what are your mixture screw settings? 2.5-3 turns out to start. Also sometimes I have found that you may have to close the throttle adjuster or open it depending on where it's set to allow more or less initial air into the system. If it's open too far it can cause problems.

 

[IT-simon]

I'll see if this happens to me, i'm doing the same thing to my bike through today and tomorrow, hope to have it running by monday, taking it slow apparently, my wife doesn't agree with me spending more time on the bike than her, until she gets her own bike.. lol

 

[jwhelan65]

How is the battery?

 

[ironsheik]

Battery and charging are perfect and I've tried 2, 2.5, 3, 3.5 turns out on the mixture screws. I did a quick bench sink with a tiny cotter pin so I figure the throttle is set pretty well...

 

[Calvin Blackmore]

just an absurd question and maybe i missed it

do you have spark on all plugs?

my bike just rolled over and died due to a faile signal generator
simple stupid thing sorry if you mentioned it was ok

 

[almarconi]

Make sure to fill the fuel bowls by putting the petcock on prime. Try a spray of carb cleaner into the airbox, this will usually get it started.

 

[ironsheik]

I found the first problem and it's really quite dumb. I pulled the carbs and checked the floats which were close to 21.5mm. Anyway, I neglected to punch out 2 of the holes in my carb bowl gaskets so there were a couple of passages that weren't functional! Hence no idle..

I got that far and now it starts but now as soon as I give it throttle it dies. If I choke it, it runs really high at around 4-4.5krpms and also won't take throttle but backfires when I try. The slides are all in great shape without tears in the rubber and all my rubber boots are in great shape (tested by spraying wd40 while it ran - no change). All pipes are pretty hot although #1 is just a tiny bit cooler than the rest. I'm a little perplexed. Any ideas on what to look at now?

 

[TheCafeKid]

I found the first problem and it's really quite dumb. I pulled the carbs and checked the floats which were close to 21.5mm. Anyway, I neglected to punch out 2 of the holes in my carb bowl gaskets so there were a couple of passages that weren't functional! Hence no idle..

I got that far and now it starts but now as soon as I give it throttle it dies. If I choke it, it runs really high at around 4-4.5krpms and also won't take throttle but backfires when I try. The slides are all in great shape without tears in the rubber and all my rubber boots are in great shape (tested by spraying wd40 while it ran - no change). All pipes are pretty hot although #1 is just a tiny bit cooler than the rest. I'm a little perplexed. Any ideas on what to look at now?

Which of the stage one jets did you use?? Are you running the lid or not on the airbox?? FWIW, I would suggest that if you didnt, you use the LARGER of the stage 1 jets, if not the smaller of the stage 3 with that Yosh (HIGH flow pipe) and KN inbox. Other than that, it honestly sounds like its running lean or there is a vacuum leak somewheres... You looked at your plugs now that its running??

 

[ironsheik]

Yeah, it's lean I think. I'm running a K&N with the lid on and I used the DJ 114s. It ran ok before with stock jetting. I'm thinking vacuum leak or one of my pilot jets is clogged. Also, what is the significance of the rubber plugs over those jets? I got replacements and while better fitting than stock I don't think they're plugged in really tightly. I'm guessing that's normal?

If not the rubber inlet boots, where else would a significant vacuum leak occur that could cause this? Thanks for all the advice so far!

JOsh

 

[TheCafeKid]

Yeah, it's lean I think. I'm running a K&N with the lid on and I used the DJ 114s. It ran ok before with stock jetting. I'm thinking vacuum leak or one of my pilot jets is clogged. Also, what is the significance of the rubber plugs over those jets? I got replacements and while better fitting than stock I don't think they're plugged in really tightly. I'm guessing that's normal?

If not the rubber inlet boots, where else would a significant vacuum leak occur that could cause this? Thanks for all the advice so far!

JOsh

Those rubber plugs SHOULD be pretty snug. They are what keeps the pilot jet from pulling fuel unmetered from the bowl. The pilot jet is fed through a smallish port in the main jet/needle jet/emulsion tube.. If the carbs are sucking air freely around the airbox boots, that would cause a lean issue as well. Did you replace those boots? I have had a couple of 1100 airboxes recently and every single one of them the rubbers were junk. The two center ones will shrink back toward the box itself, and they wont seal worth a crap on two and three... the boots should slide all the way up to the little "stopper" tab on the side of each carb mouth..

 

[dcil]

gonna sound stupid but try this. on the right side of you airbox where the holes are that it gets air thru, put a peice of duct tape over one hole and see what it does. if it revvs good, check the seal on the boots between the airbox and the carbs.

 

[ironsheik]

Got the bike running by raising the floats to 22.6mm (measured from the body) and I also pulled the pilots and sprayed them with cleaner just in case.

Something funny happened when I first got it running though. The first three times I tried revving, the motor died just like before. I played a tiny bit with the choke and then I put my hand over the air intake (I think the choke was off) to restrict the air as dcil suggested and it then starts revving really high.

It seemed to be in response to what I was doing with the airbox but maybe it just warmed up because I had to back off on the idle screw quite a lot to pull the idle down to 1k and then the bike ran normal! Not under load quite yet though...

Now I've got hesitation from 2-3k or so in any gear under load. After that, it's a rocket. I turned the mixture screws out to 3 turns and it's better but still there. I'll try 3.5 but I don't think that's the overall issue. Plug chops in this zone (1/5 throttle, 2.5k rpm) show I'm a bit lean. I'm thinking there is a vacuum leak so I ordered all new intake rubber. I figure it can't hurt even though it ain't cheap.

I've been reading up on people with similar problems and while all the threads point to some great tips, no one ever came back to report on final success or failure. I'm going to try and stay on top of this one... So would a slightly bad sync do this? I bench synced 'em pretty good and it sure seems really smooth. I don't think I can be far off... I'm assuming attempting a sync with a possible vacuum leak would be a bad idea. Ah yay! The joys of CV carbs!

Also, I my valves were just adjusted and charging seems fine.
Josh

 

[Steve]

Got the bike running by raising the floats to 22.6mm (measured from the body) and I also pulled the pilots and sprayed them with cleaner just in case.

Please remember that "raising" the floats while they are upside down on the bench is actually "lowering" them while they are running. Evidently you were running a bit too rich due to the raised fuel level.

Something funny happened when I first got it running though. The first three times I tried revving, the motor died just like before. I played a tiny bit with the choke and then I put my hand over the air intake (I think the choke was off) to restrict the air as dcil suggested and it then starts revving really high.

By reading this, I get the impression that you do not have an air box installed? :-k
These carbs need some restriction to run correctly. A stock airbox is best for all-around riding. Pods are OK, but need jetting to compensate. You apparently have a K&N filter in the stock airbox. Still needs to be jetted (apparently you have), but an air filter needs to be installed for the bike to run at anything over idle.

If you just want to make a quick check before installing the airbox, fold a shop rag in half, place it over the carb intakes, clamp it to the outer carbs with hose clamps or zip-ties, keeping it taut over the inner carbs. This is good enough to go for a test ride, but not good enough to do jetting checks.

Now I've got hesitation from 2-3k or so in any gear under load. After that, it's a rocket. ... So would a slightly bad sync do this? I bench synced 'em pretty good and it sure seems really smooth. I don't think I can be far off... I'm assuming attempting a sync with a possible vacuum leak would be a bad idea. Ah yay! The joys of CV carbs!

If the sync is off, you will notice it the most at low throttle openings. If one of the carbs is considerably more closed than the others (much higher vacuum on the gauge), when it finally opens up, yes, you will notice a bunch more power, now that all the cylinders are pulling.

You are correct, any vacuum leak will definitely show some funny readings on the gauge when you try to sync them. One thing that has caught me a time or two (or three, or ... ), be sure to plug the vacuum hose to the petcock.

.

 

[ironsheik]

Please remember that "raising" the floats while they are upside down on the bench is actually "lowering" them while they are running. Evidently you were running a bit too rich due to the raised fuel level.

Yup, understood. I mean raising them for a richer mixture. I'm never quite sure which orientation people mean when they say raising or lowering the floats. I always go by fuel level.

By reading this, I get the impression that you do not have an air box installed? :-k

Nope, I got the airbox on and all tightened up everytime I test the sucker.

I doubt it's a sync issue because they are all really close. Hopefully replacing the boots does the trick. Then I'll sync and see where I'm at. I bet I need to raise the floats a hair more since I'm running the big Yoshi race pipe and a K&N air filter. Will keep you posted.