In order to prepare for the dyno day i've been looking over the bike... (new clutch finally.. can't believe how much quicker it is without a slipping clutch :D) valve clearances / carb balance etc etc.

Anyway, now everytime I gas it to 10k+ rpm and chop the throttle I get really really loud backfires on the overrun (std exhuast system / std airbox.) Engine tuning isn't something im too great at so any suggestions as how to proceed would be helpful.

While I understand that some popping is 'normal' for a decent tuned bike these are like shotgun blasts (although pretty cool i'd like to minimise them)

I've checked everything listed above and it's all near enough standard.

I have the following theories.

Exhuast system letting in air (i.e bad sealing joint)
Pilot screws too lean
Bad Coil / Spark Plug.

Anymore suggestions / hints & tips before I rip it to pieces on Sunday.

Many thanks.

Leaky exhausts are the usual culprits for these IMO

As CMSMJ1 said leak in exhaust.

Ok cool,

I'll take it to pieces tomorrow (^_^)

Check your pilot screws aren't too rich.

Stickshift wrote:Check your pilot screws aren't too rich.

They were 2 turns out originally, i've got them set to 3 turns out now (riiiiiich) just to test and its still doing exactly the same... although has a really smooth idle now!

I can feel a few slight air leaks from the exhaust system so going to seal up the exhaust system properly first and go from there :)

Thanks for the advices.