Author Topic: Fuel Problem? Any ideas where to start (Read 4506 times)

pendletonbandit · « **on:** June 06, 2006, 09:28:07 PM »

Bought my bike about 2 months ago. Put a thousand miles on it and then one day I have a problem. I start it up and it won't idle and sounds like only three of four cylinders are firing it rides but with a 25% loss of power and won't idle on its own. So I remove the spark plugs, 1-3 look good but four is fouled so I clean all of them and reinstall. The bike runs fine for a week then my problem returns but this time a new symptom. As I give the bike a little gas to keep it running it smokes so I shut it down. Then I see some liquid dripping from where the can attaches to the muffler pipe. The liquid smells like gas. Any ideas what could be wrong? Where I should start etc. I am about to repull the plugs as I have replacements available but obviously the problem is either carboration or worse . . .?

scooter69 · « **Reply #1 on:** June 06, 2006, 10:20:23 PM »

sounds like you have a distributor problem. I would pull off the 4th plug wire and see if it makes any difference. If not, it could be the wire, faulty plug, or you need a new distributor (or whatever it's called on a bike).

Red01 · « **Reply #2 on:** June 07, 2006, 11:31:24 AM »

Like most bikes of the last 30-40 years, there's no distributor!

You have a crank trigger & ignition box (which are obviously working since it runs), and two coils. One coil sparks cylinders 1 & 4, the other one sparks 2 & 3. (They spark every time the piston approaches TDC, meaning they spark on the power stroke and the top of the exhaust stroke.) The coils are obviously working since only one cylinder is dead. This leaves us with it being a plug wire - swap 1 & 4 and see if the problem follows, or a bad plug - swap plugs 3 & 4 and see if the problem follows. If the problem moves, you've found the offending part. If #4 is still dead, then there's either a carb problem or compression loss great enough to cause power loss.

tacoman · « **Reply #3 on:** June 07, 2006, 01:54:35 PM »

It sounds like a carb problem to me. Too much gas getting in. I'd say a stuck float? You might have some gunk floating around in that carb and it gets stuck in the float needle or the jets. We've had a lot of dirty carb/fuel problems lately and I think its because of bad gas out there. I'd say replace the plugs when you get them and add some Chevron Techron to the gas. Techron worked for me a few weeks back and a few others here as well.

Red01 · « **Reply #4 on:** June 07, 2006, 04:25:38 PM »

Well, Taco, a cylinder that's not sparking - or doesn't have enough compression - will pump raw fuel into the exhaust just as well as a carb that's too rich or flooding by the float needle & seat.

99er · « **Reply #5 on:** June 09, 2006, 09:17:35 AM »

That's funny, my #4 did the same thing. Bad o-ring on the float seat flooding the carb. It ran great wide open but spit gas on idle. Did the whole track day with it like that.

You can drain the bowl and hope that there's an obstruction that comes out with the fuel. You can remove the bowl with the carb intact and check in there. You can remove and clean the carbs. Choose you poison.

Change the plug. I've had limited success with plug cleaning and Autolites are super cheap at $2.99 or so for a package of two at Advance Auto. I just saw a plug on another bike that looked acceptable but actually measured 1 MOhm on a DMM. I used to scrub mine and then heat them to a glow with mapp gas. Only limited success.
Marc/Atlanta

pendletonbandit · « **Reply #6 on:** June 12, 2006, 02:35:44 AM »

Thanks for all of the tips. I checked the spark, all four where fine. Then I moved to the carb. Drained it and removed the number 4 bowl. found the little bugger that was causing the float to stick and its been running great ever since. Thanks for everyone's help.

tacoman · « **Reply #7 on:** June 12, 2006, 02:22:32 PM »

Aha, I did diagnose it! I learned this symptom well from an old Honda I had. I would clean/fix the carb and it would do it again. I finally realized that when I went to the gas station I was pulling the nozzle to hard and it was like pressure washing the inside of the tank. I would loosen up a bunch of crude and it would find its way to the carb.

motoproponent · « **Reply #8 on:** August 02, 2006, 05:34:45 PM »

Hey every one, new to these boards. I've had my bandit new since 01 when I bought it. I started modifying it last year and have a very similar problem. Only mine runs on 2 cylinders and till you close the choke the it hits on three but fuel runs out of the inside right hand carb. Imonna give them a good cleaning and see if that helps. I'll keep you posted.