MOPED ARMY

I have found that if you get the exhaust walls parallel to each other, meaning equal widths on your exhaust window to the inside of the ring for the crush washer. thats about where you want to stop. any more and you get really close to the ring ends, looking at your measurement its already pretty close.maybe its not and just looks that ways cause its flat, makes any sense?

Man, are my English skillz and spelling in the toilet today!

I just ported my stock cylinder (but yet to run it) and I followed the blueprints in the wiki. I was in contact with some very knowledgeable French tuners and they all recommended following those instructions. See this page for some before and after shots of following the blueprint instructions.

Widening the exhaust is recommended for better gas flow and I assume allows it to rev higher.

The 'fast' cylinder is not that fast at all...

I never calculated the port timings or mapped them but I assume it was a 25mph cylinder. It had an intake that was the same size as the one on my B speed motor, fitting the 9mm stubby intake perfectly (idk if the larger bendy intake had a larger opening, but on the before pic on that site, his looks MUCH larger then mine stock) and the transfer ports are the same shape and size. I snagged the cylinder from a pile at the kzoo 1977 moped fire sale and didn't know it's history.

The cylinder transfer ports appear to have similar width to the stock ports in the French article so they might be the same. I cant get any measurements from it now (all bolted together and not redoing that).

Talk to Jesse S. about porting out the moby to specific timings, that way you no longer have to talk about raising them X mm anymore just degrees. Still have to figure out optimum width another way...