Dear all,

i tried to find an answer on the internet but can't get one.

Wich effekt does it have on a 2 stroke when i shorten the aluminium housing (shaft) where the exhaust pipe is sitting in. The exhaust pipe ist just cylindrical with an open end. So no tuner there. Does the motor extremly change in power when the backpressure is influenced by a modified housing with less volume?
I see i.e. mercury racing motors with ultra short shafts. They should have a similar problem...

Dont start loughing, but i like do this to a 3HP Yamaha Malta.

DIY dyno is already finished;-)

https://www.youtube.com/watch?v=W6F1K8IYDhM

Any answers are highly appreciated!

Thx
Oliver