www.zxrworld.co.uk

I know this is a ZXR forum, so probably going to get flamed for this!

My girlfriends little brother has just bought a Derbi GPR50 for when he turns 16 shortly

Its running with a flatspot at 5-6k

Its also got a new Arrow exhaust.

Im trying to help him as much as I can with my limited knowledge, but thought the cure might be similar for most bikes?

After reading around, I think it might be that the carb isnt jetted properly for the new exhaust? or something similar?

I know its off topic but any help would be vastly appreciated!

Cheers, Jack

Deffinately going to be the jets as its 2 stroke and carbed, my advice would be get it sorted on a dyno and jetted accordingly as well as replacing the spark plug, jobs a gudden