Backfire
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Cruiser
Joined: Sep 2010
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From: CA
Backfire
Hey, finally got my bike on the road, dropped her off at the dealer so they could do the initial start up for the warranty,(glad to get that freaken part done) and I had them throw on two new tires. picked her up today rode her home and then to work. it's backfiring through the exhaust alot especially on down shifts. it's has only backfired through the carb a few times, while I am at idle the carb is wistling, sounds like it's sucking in a lot of air. other then that the engine is strong and smooth. I am fairly sure I have a tuning problem with the carb, just wanted to see if you guys knew off hand what exactly it could be. and wanted to know if the back firing through the exhaust was normal on a rebuilt engine until it gets broken in. I will be looking at it in the morning.
Thanks
Tired Bird
Thanks
Tired Bird
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Joined: Jan 2009
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From: Los Angeles, CA
What kind of exhaust do you have? I assume you have a carb? Try adjusting the mixture screw on the carb and see if that help first. Check for exhaust leaks at the port and at any exhaust connections.
Drew
Drew
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Joined: Jan 2009
Posts: 19,364
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From: Los Angeles, CA
S/e 2 exhaust is usually slip on's. Did you put new exhaust gaskets when putting them back on as well? that is always recommended. You could also put some ultra cooper on the joints where the slip on's connect to the head pipes for extra sealing power.
Drew
Drew
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From: CA
Yea I used new gaskets for the exhaust. I was thinking they were slip ons but the pipes run lower then most. But that could be because most bikes around here are newer then mine. I can't find any leaks in the exhaust. so I think that area is fine.
for the life of me I can't find the fuel mixture screw. And the manual I have is no help. So far I have been very disapointed in my manual.
On a side note. I noticed the evap system isn't hooked up. Could that cause the backfiring. the canister has he two hoses comming out of it but they don't connect to anything. Looks like the port on the carb where one hose is supposed to be is capped off. And the vent hose comming out of the tank does go all the way back to the seat area. I would need to lift the tank to find out where it stops. I am not worried about it if I can't cause the backfiring but if it can then I guess I need to figure that out.
for the life of me I can't find the fuel mixture screw. And the manual I have is no help. So far I have been very disapointed in my manual.
On a side note. I noticed the evap system isn't hooked up. Could that cause the backfiring. the canister has he two hoses comming out of it but they don't connect to anything. Looks like the port on the carb where one hose is supposed to be is capped off. And the vent hose comming out of the tank does go all the way back to the seat area. I would need to lift the tank to find out where it stops. I am not worried about it if I can't cause the backfiring but if it can then I guess I need to figure that out.
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Joined: Nov 2007
Posts: 2,289
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From: Beautiful Downtown Burbank
Spitting through the carb is an indication of a lean condition. You cant find the mixture screw because its hidden behind a aluminum plug in the throttle body. Pull the plug and you can richen the idle mix where you want it.
Backfiring is usually caused by exhaust leaks. Loosen the manifold nuts and jiggle the pipes until they take a seat in the head. Then tighten the nuts a little at a time (and equally) until everything is all snugged up. Then put the final torque on it.
Since youve got a bit of spitting out of the carb, I'd start there first. Have you done any previous carb work to it or is it stock?
Backfiring is usually caused by exhaust leaks. Loosen the manifold nuts and jiggle the pipes until they take a seat in the head. Then tighten the nuts a little at a time (and equally) until everything is all snugged up. Then put the final torque on it.
Since youve got a bit of spitting out of the carb, I'd start there first. Have you done any previous carb work to it or is it stock?
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