Fuel Issues

[danmwarren78]

The last few times I've ridden my 73 Combat Wambat, I've taken it out and ran I hard and after 15-20 min. when I give it gas it bogs down. It will idle but not run. After a few minutes it will run for a few minutes but you have to keep messing with the throttle while it keeps boggin down. I've changed the jets replaced fuel lines and filter, taken carb. apart and cleaned and it still happens. Not sure what to do. Fuel looks clean, not sure what to do. Any ideas?

Thanks Dan

[socalhodaka]

Give a little more history, how long have you own this bike? What is your fuel mixture? how does the plug look? When you said change jets? what jets and did you change sizes? Needle position? Lets see some pictures.

[danmwarren78]

I've had the bike 2yrs...Danny Cooke rebuilt the motor and wen't thru the bike completely a little over a year ago and did a great job. For the last year I've been riding every other weekend at least 20 mile trail and some tracks. Fuel mixture 32 to1. Been using 190-210 jets. Just lowered needle to 3rd position. However 2 weeks ago bike broke down and wouldn't start, when I took the carb apart the clip had come off the needle. Put it back on and lowered it to 3rd because seemed to be running rich.

[viclioce]

Sounds like you may have moved the clip to a richer position than where it was? Do you know for sure which position the clip was in when Danny sent it back to you? That would be my first guess.
; D Victor

[Dale]

It could be the result of any number of things. If it used to run fine and without changing anything it now bogs, then it is probably not jetting (unless something has plugged up).

If it begins doing this after running okay for 15-20 minutes then I would suspect a plugged vent on the fuel cap. It sounds like it is starving for fuel. Petcocks flow freely? Fuel filter clean? Fuel in lines visable?

Another item that I would be suspicious of is the exaust pipe. They have to be kept clean.

I know my C/W is very sensitive to the air screw adjustment. If an eighth of a turn lean (out) it will bog horribly until fully warm. But this sounds different from your issue.

[viclioce]

Sounds like it could also be an ignition issue. Very much like a fouling plug, but just as likely a failing condenser and/or coil.

The fact that it runs fine for ten or fifteen minutes is a clue. After ten minutes, the engine and ignition are hot, but far past merely fully warmed up. The ten minutes implies a heat soak problem causing the spark to degrade. It will idle but not sustain anything above idle. Basically it is blowing out the spark because the spark is weak. Check coils for spec output, check condenser likewise, verify solid grounds everywhere. But my best guess is coil, possibly the secondary under the tank, or the condenser. Initially a condenser can fail after getting hot but may not do it when the motor, which within it lies is cold until it gets hot, making the condenser overheat as well.

I hope you figure it out! I had an old Kawasaki F6 that used to just blow a condenser in the middle of a ride and just quit working completely until the condenser was replaced. Then it would run fine again for a couple of years until the condenser wore out and blew again. Sometimes it's all of a sudden & sometimes it starts off as intermittent. ; D Victor