Have got a bosi for the 300 4T Evo and need advice on setting up carb, with original carb settings it seems to have a little sort of cough at about 1/3 throttle. Also flames from the exhaust with a backfire

Any advice please

Thanks

Edited September 1, 201213 yr by wright4d

Did you use new gaskets and sealant on all the joints? If not you may have an air leak. Doe sit pop and bang on over run?

Yes it's on the over run and on the standard exhaust, sealing the exhaust solved the issue of the back fire, I'm more concerned with the flames and the slight cough at 1/3 throttle could this also be caused by the exhaust sucking in air ?

Thanks

Could be a few things causing it,

1. Check CDI box terminals how any bits of muck or water inside, Make it is completely clean, This has caused problems with the 4T's.

2. Maybe there is a little bit of water in the Carb?, Undo the drain screw at the bottom of it.

3. Could be an air leak on the carb inlet manifold rubber, These have been known to split on the 4T's, And can cause the same sort of problem that yours is having.

Any "extra" air from a pin sized hole or split in the induction or exhaust system can give you issues. On induction it will cock up fuel ratios etc and on the exhaust side of things it allow more oxygen into the pipe which then allows unburnt fuel to ignite in the pipe which gives back fire etc. Ride at night for full effect!

I try Benbetas suggestion of check oeverything is clean and ok. Make sure all is sealed against possible air leaks properly. The carb sounds like water or dirt to me as the cough happens when going from the pilot fuel circuit to the next circuit in the line. There is a recent post on here exactly what a carb is doing and when.

4Ts are more susceptible to issues stemming from manhandling the bike by holding the exhaust pipe etc. Time for a thorough clean, check and re seal. If you have issues after that you can fault find more effectively.

Edited September 3, 201213 yr by pindie

Thanks for the replies I will look at all the suggestions when I get back from a job away in November.