My bike has recently starting doing this thing where it will surge, sputter, and backfire, almost like it doesn't have a steady fuel flow. Sometimes it's not that bad, other times it's so bad it's practically bucking me off the bike when I'm accelerating. It doesn't appear to have any dependance on the weather, or if the bike is hot or cold. It's completely random too. I've had it so bad I almost drove it straight the the mechanic, then had it stop and not do it again for a week.

I did have the mechanic check it out and I don't think it had any problems for the 3 test runs he took it for. He thought it might have something to do with the exhaust I have on it, (the previous owner put it on, I don't know anything about it) and it not creating enough back pressure for the carb. He told me he thought the engine was running strong and the bike was carbureting well.

Any suggestions?

Do you by any chance, have a 87 savage?  When my 87 started bucking it was the white spacer.  take the top of the carb off, replace the spacer with a nylon washer and put it back together.  Search for white spacer and you should find it.  It was not hard to do.

yep, see if it does it in prime.

then check the kickstand, if it doesn't hold up over bumps then it'll cut out.

I vote petcock...try running it on prime for a while and see if it goes away....make sure you keep filling up the tank tho'

big heel on your boot hitting the kickstand???

Hey guys, thanks for all the help! I think I may have found the problem. I replaced my vacuum tube (it was kinda old, but didn't have any cracks or anything...). Since I've done that I haven't had any problems. It's been over a week, but I'm keeping my fingers crossed.

As for that white spacer in the carb: I have been having some issues which I think are carb related. Mostly backfiring when I let off the throttle (which I know is pretty common) and I'm even getting some flames out the back of the exhaust. It's not a stock exhaust, the guy who had the bike before me put it on, and apparently didn't tune the carb to match it. I took out the white spacer, which didn't seem to do a whole lot... maybe make it backfire louder... I think I'll end up replacing some of my jets with different sizes.   Don't you just love tuning a carb?

Still no problems since I replaced that vac line! Looks like that did it. Thanks for all the help guys.

As for the backfiring, I turned out the pilot air jet a turn and took out the white spacer. Still backfires, but it's much, much better. Gonna get a hold of some washers and try it at 1/2 spacer, see what that does.

Quote:
Don't you just love tuning a carb?
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Yes, but only when I know where I'm at, and why I'm doing it.
Modding a carb for an inconsistant problem, is normally not the answer.
Some here are modding carbs as just a shot in the dark