Basic port chamfering

[halfmanhalfninja]

Been a while since I worked on 2-strokes...have my daughter's bloody Peugeot Vivacity 50 to repair (again) and have a slight snag, would appreciate your advice;

Engine - Peugeot 50cc AC horizontal engine. Has just had new crank and bearings.

Problem - put the existing barrel and piston on, and as I turn the engine over by hand, the piston will stop on either to top or bottom edge of the exhaust port. With a little extra effort, you can make the crank turn but it wants to stop every time the piston passes the exhaust port.

Take the barrel off, and the problem stops - so the problem doesn't stem from from elsewhere in the engine. Piston is installed correctly, the ring-ends are 180 deg from the exhaust port.

So, I checked the port chamfering - the edge was dull anyway, but I gave it the riffler file to make sure it has a chamfer (did the other ports too) and still the problem is there, although it's slightly reduced.

Can anyone tell me what the ideal angle and width of an exhaust port chamfer should be?

[John21]

 

 

 

 

[halfmanhalfninja]

Thankyou kindly Sir

[John21]

Glad to be of service.