Horiz. Minarelli exhaust port outlet restriction

[50cczip racer]

put simply exhaust port outlet and exhaust manifold needs to be same size/area as the ex port window on the cylinder wall

 

[muhuha]

I also have had experience of porting the exhaust port of a stock cylinder, i rounded it, widened it and raised it a gair amount, using a derestricted stock pipe (TP Powered) i could get 80-90kph and down a hill over 100kph, there wasnt any power due to the pipe, but when i have my x-pro it gave loads of power shame i didnt have it to test how fast i coulda gone. Obv the clocks are out a bit but my dragster clock is a bit more accurate compared to piaggio crap. - they do 70mph which im overtaking them doing 55 on my clock...

 

[animojog]

my stock jog artistic, goes over 80kph flat road ,, stock pipe, 3kj cylinder/ head , stock gear, full body... Im 110lbs / 5'3" tall