Well here is the latest

we have checked every single electrical connection and cleaned them all

adjusted the valves

cleaned everything we could see and reach with a cloth

someone suggested that we hold the throttle wide open and kick it 3 times (which i guess re starts the computer)

the bike still back fires and the plug is still black running rich you can even see it running rich with black smoke coming out of the pipe

any more ideas

I don't normally reply to a topic that I don't have personal experience of, however offer the following thoughts.

My 05 always ran rich and would foul plugs regularly, after checking all readings we eventually swapped all components systematically with a mates bike (Painfull process). In my case nothing changed until we swapped the throttle body and then the bike was completely different. I obtained a new throttle body and that bike has been fine ever since.

I reckon in this case though I think you have two different things going on running rich should not give significant backfiring on the over run, in fact it is normally a sign of a weak mixture or an air leak.

On carburreted bikes at the shop backfiring through the exhaust on the over run was always traced either to an air leak in the exhaust or a burnt exhaust valve (as others have noted).

Now the bit I am not sure of is with an injected motor is it possible for a faulty injector to dribble rather than cut off clean after injection (this is common with diesel motors) I would guess a small amount of fuel getting into the cylinder could produce ignition when the exhaust valve was open?

Personally would still see the most likely cause of backfiring to be an airleak and probably at the barrel to pipe joint, have you cleaned out that area and put new seal in?? Good luck

Edited October 30, 200718 yr by oz thumper

well thanks for everyones input

here is the final words "exhaust leak"

one of the header to cylinder bolts was loose tighten it down and the backfire stopped

thank you

well thanks for everyones input

here is the final words "exhaust leak"

one of the header to cylinder bolts was loose tighten it down and the backfire stopped

Only just picked up on this thread, that is a common four-stroke trait, if cold air is drawn into the exhaust at the manifold on any four-stroke, it tends to cause an explosion in the exhaust system, only on the "over-run"!

Big John

thank you

Well m sport strikes again, perhaps if you can diagnose faults instantainously from a forum perhaps you can answer this, when the are 2008 4rts landing in the UK.

soon

soon

free beer tomorrow

Edited November 4, 200718 yr by PERCE

he doesnt drink