The V8 Owners Forum -

Hi went out on my trike and all going well nice tickover and pulling away got home reversed it up the drive . all ticking over nice but when I took it out of drive the engine revved up to about 2000 rpm then after about 30 secs it ticked over as normal. the engine is in the open and the throttle was closed on both carbs so not a sticking throttle. anybody have any ideas. thanks in advance.

SU carbs? There is often a designed amount of free play between the carbs, so one opens before the other for smoother control at low speeds. So one carb might stick open slightly even with the throttle closed.

Hi thanks for your reply but both carbs were fully closed. the engine is in the open so easily checked.

Something must be letting air past a butterfly within a carb, then. A sticking poppet valve in the butterfly?

Thanks I will strip the carbs down and go through them. I thought it might be in the carbs. thanks again.

Can I do away with the poppet valves?

Yes. They are there to stop excessive leaning out of the mixture on overrun. You might get farting and popping on overrun, but otherwise no issues.

Chris.