Hi All,


I'm struggling to set up a OS 91 Fx with a baffled tuned pipe. I'm not sure how long it needs to be.
THe formulae for calculating the length all require exhaust port duration in degrees and well surprise surprise that information is not given in the manual.

would be greatly appreciated yif you could assist with the exhaust port duration or length of tuned pipe required for this engine.
My header is 29cm from the centre of the piston or 27.5cm from the exhaust flange.</p>