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Im Stumped!!!!


LJWalter

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Help me OR!

Heres what i got; 

99 Suzuki GSF600 Bandit with 15k. It would idle ok, but when you hit the throttle, it dies out.. 

I pulled the carbs & found that 2 of the diaphragms were torn. Went ahead & replace all 4 to be safe. Carbs back on & still the same issue... 

Any help would be much appreciated! 

Cheers!

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vacuum leak problems mostly go away when revved up. Sooo, fuel flow or spark.

 

Roughly, if the plugs are dry, it's lacking fuel.

If the plugs are wet, it's lacking spark.

 

edit: I hate carbs with diaphrams. They are always breaking. But they are smooth.

Edited by ReconRat
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Check fuel lines, also-and this is critical- there's a little o-ring there when you take off the diaphragm cover. Its very small and easy to lose but extremely vital to the diaphragms working properly. Is the bike set up stock? Has someone given it the bro treatment (piped, jetted and pod filtered it)? Vacuum pet cock functioning correctly (if applicable)? Is the TPS hooked back up on the #4 carb? (if applicable)

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Check fuel lines, also-and this is critical- there's a little o-ring there when you take off the diaphragm cover. Its very small and easy to lose but extremely vital to the diaphragms working properly. Is the bike set up stock? Has someone given it the bro treatment (piped, jetted and pod filtered it)? Vacuum pet cock functioning correctly (if applicable)? Is the TPS hooked back up on the #4 carb? (if applicable)

Yes, it is piped & jetted. vacuum on petcock is working. Diaphragm in petcock it tact as well. I did not notice an o-ring tho..... Got anymore details on that?

Thanks a mil!!!!

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good point, that's one vacuum leak that will shut off fuel. The o-ring seal on the lid at the carb diaphragm.

I suppose we can count the vacuum operated fuel shut off petcock also.

 

Exceptions to every rule.

 

edit: I think some carb diaphragms have the seal built in, and no o-ring. but I've seen some leak where I've had to seal them with something. Cheap trick is grease them where they need to seal. Might swell up and break again, but if they live through fuel and alcohol, I don't figure grease is going to hurt them. I'd have to know what type of polymer/rubber they were made out of to know for sure.

Edited by ReconRat
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If you have the same carbs that I have on my 03 bandit 1200 then after you remove the top of the carb there is a little port outside the outline of the diaphragm. On mine if the motor side of the carb is noon and the filter side is six, they are at about 1:30. The only thing that holds the little o ring in is the lid and sometimes they will stick to the lid and then fall off later. Losing those o rings will shut a bike down. It could also be that you need a carb clean. Are the bowls filling up? Crack the drain screws and see if gas is for sure making it down to each carb, possible you have a flow issue.

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Thanks everyone for chiming in. After some research there are no o-rings for the diaphragm covers. I am leaning more towards fuel flow. Like i said, when the bike is cold (carb bowls full) it revs just fine. I believe after it burns through what is in the bowl, it does not replenish fast enough. All fuel lines are clean. Is there a way to test the petcock other than replacing it? 

Thanks again!!

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Sure, get the bike running and pull the fuel hose off the petcock. If gas comes out, its working. Will it rev on choke? You really need to go get some clear plastic hose, hook it to the bowl drains and bend it up against the carb, that will act as a sight glass for your bowl levels. If you think it might be the petcock, put it on prime, that lets fuel flow whether the motor is running or not. Its also quite possible that you just need a carb clean. Where in Ohio are you?

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Sure, get the bike running and pull the fuel hose off the petcock. If gas comes out, its working. Will it rev on choke? You really need to go get some clear plastic hose, hook it to the bowl drains and bend it up against the carb, that will act as a sight glass for your bowl levels. If you think it might be the petcock, put it on prime, that lets fuel flow whether the motor is running or not. Its also quite possible that you just need a carb clean. Where in Ohio are you?

The carbs are clean as they can be. Jets are clear, etc. I am in Hilliard, nw suburb of Columbus. Sucks because Hoblick was about a mile from me b4 he moved... lol

I will try it on prime. Thanks again for all the help!

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