Had slight carb problems... tried to sync them, now no run!!

joedude · July 07, 2005, 09:27:19 AM

Hey, so a few days ago i pulled my spark plugs off and noticed that one was black (right)... like really black, and the other one was fine(left). So I figured that the mixture was too rich on the right side. The solution i figured out was to sync the carbs, so i built a vacuum synchronizer and went to work. i got em as close as i could, but then my bike started backfiring.... like flame coming out of the exhaust pipe! so that freaked the hell out of me. i tried to bring it back to where it was before, but it stalled while doing this and now it wont start! not a sputter, nothin.

did i try the wrong solution for the problem? how do i fix the mixture issue and keep my carbs synched.... and more importantly... how do i get the damn thing running!!!! :x

Please reply.... i want to go to the beach this afternoon!!!!

The Buddha · July 07, 2005, 10:15:20 AM

OK exhaust fire ... ok I will almost say with certainity - having seen 2 only bikes that did this, and both did it for the same damn reason ... If you have new NGK spark plugs - toss them, get Champion 809 and the problem will disappear ... if old NGK's well swap it for new champions ... and they might disappear ...
Cool.
Srinath.

joedude · July 07, 2005, 10:21:08 AM

ok, i'll go get new plugs. what about the mixture issue? any ideas?

The Buddha · July 07, 2005, 10:33:42 AM

Your plugs being black on 1 side and normal on the other doesn't mean it needs a synch ... it probably needs floats set right and equal in both and needs air screws fixed to be equal too ...
Cool.
Srinath.

joedude · July 07, 2005, 10:36:57 AM

any hints as to how to do all that stuff?

Kerry · July 07, 2005, 01:05:40 PM

Flame from the pipe means that fuel is not being burned in one or both cylinders (or is being incompletely burned), and is then being expelled through the exhaust pipe, where it is ignited either by the heat of the header/pipe or by a stray spark of some kind.

When my bike had these symptoms (sooty plug on one side, occasional backfire) it was because a corroded connector was interfering with the signal generator circuit, which meant that one of the ignition coils wasn't getting fired off quite the right way.

I performed a spark check on both cylinders (holding the threads or other metal part of the plug against the cooling fins) ...

... and I was getting spark on both sides, but the spark seemed a little yellow (as opposed to a nice blue).

I even constructed a spark strength checker, but the spark (still yellow) jumped the gap just fine on both cylinders:

It wasn't until I went down a list of electrical resistance tests that I found the problem...

... which I eventually fixed by replacing the entire corroded connector with 4 individual quick connectors:

I would be surprised if you have a corroded connector, but it DOES sound electrical. Any other clues you can give us?

joedude · July 08, 2005, 01:52:25 PM

alright, i pulled my carbs off, cleaned them out, and reinstalled everything. now the bike runs! I haven't had the time to get to the bike shop and get new spark plugs... but i figured that i would let you know about another problem i'm having. as i increase the throttle input, the bike refuses to rev above 3000 RPM... it just sputters there and doesn't go any higher.... will new spark plugs also correct that?

thanks cheers!

mjm · July 08, 2005, 05:08:51 PM

Quote from: joedudealright, i pulled my carbs off, cleaned them out, and reinstalled everything. now the bike runs! I haven't had the time to get to the bike shop and get new spark plugs... but i figured that i would let you know about another problem i'm having. as i increase the throttle input, the bike refuses to rev above 3000 RPM... it just sputters there and doesn't go any higher.... will new spark plugs also correct that?

thanks cheers!

Sounds like a pinhole in a diaphram or like you left out the little "o" rings from the top of the carbs

joedude · July 08, 2005, 05:18:21 PM

update time...
I put in new NGK plugs, and the bike runs a bit better than it ran before i started playing around with it... it still doesn't quite run as smoothly as a twin should, so I'm pretty sure that there's something up with either the sync (although i doubt it cause the carbs are synched) or it could be the mixture in the right carb... which is what i think it is....
does anyone know how to adjust the mixture, and how to know wether its set properly?

cheers

PS: thanks for all the replies, its been helping alot... Kerry - turns out that my electrical is all fine, but thanks for your input, and moreso for the pics, they were very helpful in finding out that it was not the problem!

joedude · July 10, 2005, 04:21:50 PM

alright guys, i need some more help here...
The bike runs, but it hesitates at throttle inputs. and after running for a few seconds, it usually emitts a pop.... or a "pfft" (for lack of better description) from the carburetor area. and then it dies immediately, no matter what the RPM.

Please help! i need to get this thing running!

calvert0014 · July 27, 2005, 02:32:32 PM

i am having a very similar, almost identical problem with my bike.mine wont idle above 2000 rpm. i know the "puff" your talking about. have you found a solution yet?

mjm · July 27, 2005, 03:00:31 PM

Quote from: joedudealright guys, i need some more help here...
The bike runs, but it hesitates at throttle inputs. and after running for a few seconds, it usually emitts a pop.... or a "pfft" (for lack of better description) from the carburetor area. and then it dies immediately, no matter what the RPM.

Please help! i need to get this thing running!

Check for air leak at carb boots - spray WD 40 around where the carb goes into the engine side boot and where the boot attaches to the engine- if RPM goes up, you found your leak. Fixing it is generally just making sure everything is properly aligned and tightening up the connectors. It can bbe cracks in the boots - they are fairly cheap at the dealer.

When were your valves last adjusted? Check valves if it was more than 4000 miles ago. If it was more than 10,000 miles ago ADJUST THEM NOW.

Like Srinath said - your float on the carboned-up side is probably adjusted too high. I believe that there is a description of how to adjust this in the How To section.

Rema1000 · July 27, 2005, 08:48:45 PM

Sync'ing carbs will not even the air/fuel mixture between the two. All it will do, is adjust the throttle for left versus right cylinders. So if you were idling too rich on one cylinder, then tried to compensate with the sync... then all you have is a cylinder which is too rich, and has the throttle turned down a bit to compensate.

You want to make sure your float height is correct, then use the pilot jet air/fuel mixture screws to adjust each side... then readjust the sync (because it will be unbalanced by then).

Mountaineer · July 28, 2005, 08:39:39 AM

A couple other thoughts-
One, maybe there was some debris or something interfering with the float valve closing and regulating the fuel in the right chamber. Try cleaning the float valve and seat, which I think you can do with the carbs in place.

Two, how likely is it that the connection on the choke linkage could mess up and cause the choke on that side to hang up? Are you sure the choke is coming off completely on both sides when you close the choke?

I don't think improper synch would cause one side to go rich. That's got to be either too much fuel (rich) or else like Kerry says, faulty ignition. Be sure you have a fat, blue spark.

scratch · July 28, 2005, 08:45:40 AM

Quote from: mjm...or like you left out the little "o" rings from the top of the carbs

Would you confrim that these o-rings are there under the black plastic caps, please? These are the o-rings that seal around the port to the vacuum balance cap.

joedude · July 29, 2005, 02:52:38 PM

alright, so i have an overdue update. I did a float level check, and turns out that the right side isn't stopping fuel flow, so I pulled off the carbs again. and turns out that the o-ring around the needle valve seat was squared-off and was letting fuel drain into the carb. i adjusted the mixture and she now runs acceptably, but there still is the issue of the idle. it wants to die if i dont keep some throttle input at a stop. and if i increase the idle speed, it sits around 3k rpm. !?

she just turned 13 000mi, and i've just owned her for the last 3000mi (almost 2 months now) i'm not aware of any valve adjustment done in the recent past.... is that a job that i can do? or should it be brought to a pro?

thanks for all the input!

cheers

mjm · July 29, 2005, 05:22:52 PM

Your idle problem could be the valves - adjustment is easy if your follow the directions on this site. Should tke you a couple hours the first time if you do not wrench much - quicker with the right tools.

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Had slight carb problems... tried to sync them, now no run!!