50cc engine

[light4]

Hi everyone, my son (16) just got his first 50cc Road bike that is a twin cam 4 stroke and noticed there was a blanking plate over the second exhaust valve which seems very strange,we removed the plate and yes the port is a live exhaust port!, could it be a way of them limiting the power and restricting it for obvious uk rules and if so could fitting an exhaust pipe release some extra power?.

[vw_99]

Never seen that before.
Maybe the engine is used in another model with exhaust on other side of engine or twin exhausts.

[hidetheelephants]

It's likely the carb/injection will be tuned for having the plate fitted, removing it may lean it out and cause all manner of unpleasantness unless fueling is increased(if injection it's possible it may be closed loop but safer to not assume so).

[GreenV8S]

light4 said:

could fitting an exhaust pipe release some extra power?.

Potentially, but probably only with tuning and probably not very much. It would also render the bike modified. I can imagine your insurers feeling some kind of way 'bout that.

[light4]

vw_99 said:

Never seen that before.
Maybe the engine is used in another model with exhaust on other side of engine or twin exhausts.

Yeah I did think that, maybe the 125cc uses the same cylinder block and utilises the second port