Help with carbureted bike, one bowl flooding (Page 1/1)
FieroGT42 JUL 31, 09:40 PM
Copied/pasted from my thread here: http://www.vn750.com/forum/showthread.php?t=37338


I got a bike with a torn diaphragm that was running super rich. The idle screw was also set so low that it wouldn't idle, cold or hot. The bike did run if you held the throttle, just very poorly and super rich.

I replaced both diaphragms since one was completely torn and cleaned the carbs. I also rejetted to 140/40 front and 142/40 rear per recommendations here because I coastered and shaved the ears. I know, too many variables at once isn't good but I didn't want to redo the carbs.

Now the bike just cranks and cranks. When I'm cranking, fuel dribbles out of the T on the carb vent lines. From what I read this is supposed to go to tank but I don't see anywhere to attach it. It's an 86 and I read that it may not have that from the factory. Pretty sure gas shouldn't come out of there though.

Is this the carbs flooding? I drained them both and got a normal looking amount from each.

Help would be much appreciated. I'm supposed to bring this bike to a safety course on the 12th. Thanks.

Jason


Edit:
Checked that the A/F screws were at 1 1/2 turns. Started up for a few seconds on both cylinders at 1200 RPM and dropped slowly until it died. I can get it to run sometimes for a few seconds at half throttle but not idle. Both carbs are spitting fuel and wetting the filters. They're 140/40 and 142/40 jets, brand new genuine Keihin.

-----------------------------------------

No junk in the carbs. Float is airtight. Spring in the needle is springy and moves freely. Float needle rubber looks good. Pilot needle looks good.

I'm trying to find how to check/set the float level because I'm really at a loss as to what else to do. Is there any way to check them without putting them back on the bike and taknig them back off for every adjustment?? That's ridiculous...


Edit:

The only way I can find is with the carbs on the bike and RUNNING, which I can't do because it won't run. I'm kind of stuck here.

[This message has been edited by FieroGT42 (edited 07-31-2013).]

Stubby79 AUG 01, 11:56 PM
They seem to have covered everything I can think of in the other forum.
FieroGT42 AUG 02, 12:07 AM
Thanks for having a look, Stubby. I got it running. Turned out to be 2 bad float needles in a row which is why it threw me. Still pretty rich. Both bowls match at 32 mL when I drain them now instead of 24/64. I think it's driveable (rideable?) but I want to get the fuel issue sorted out.
dematrix86gt AUG 06, 12:19 AM
a little trick i learned years ago to clean needle seats. cut a q-tip in half put it in a electric drill dip it in mothers aluminum polish stick it in and polish like hell!!! Have you synced your carbs yet? i used to have a liquid sync bar for 4 carbs (i didnt know how to do it a friend of mine did) mine run rich on 2 and good on 2 until they were synced.
but i do know multiple carbs have to be synced.

[This message has been edited by dematrix86gt (edited 08-06-2013).]

FieroGT42 AUG 06, 02:33 PM
I did the same thing, just by hand. The seats weren't too bad because it has rubber needles. I'll sync them when I get some smaller jets in. It idles just a touch rich but it's belching smoke at speed. I did consider that maybe one is just running way rich due to imbalance but I think I'll need to step down jet size anyway because it's not that rich at idle.

I do have a video of idle, rev and playing with the idle speed. It's good to hear it finally run. It's a lot louder than it sounds here:
http://www.youtube.com/watch?v=dnS75-y58eE
carnut122 AUG 14, 09:00 PM
Virtually every carb issue I had on my 86 Yamaha Maxim X turned out to be petcock issues.
FieroGT42 AUG 14, 11:49 PM
Fuel issues are sorted out, thanks. 2nd new needle valve fixed it. First one wasnt' sealing for some reason.
Lunatic SEP 27, 06:47 AM
I'm glad you got it sorted out! Now get on that thing and ride! Summer goes by quickly!