Hey guys have a cbr600f4i starts and runs great but when you get to 8000rpm it splutters then jumps to 10000rpm, what could be my issue
(is not on a bike. Is in a buggy has aftermarket fuel pump)

 

Welcome to the forum.
I think you will need to give a lot more info on your current set up before anyone will have any idea how to help.
Has it ever run well, how many miles on the engine, has it had any other mods etc.

 

Ran great on the bike bike transfered to the buggy and put a fuel pump and regulator as I couldn’t use the factory one as it was in the tank, I have the fuel pressure reg set to 45 is this okay,

 

That’s the only mods I’ve done to it and has 45000kms

 

Runs great up to 8000rpm ten splutters a bit then all of a sudden jumps to 10000rpm