[Sticker Otis]

This is more a general 2-stroke question but I'm working on a LT50.
The exhaust & transfers are still partialy covered at BDC by about 2.5 mm. Seems a pretty big chunk of a port. Same on stock cylinder/piston and 2 aftermarket kits. I can space it up and machine the deck but don't know what raising the top of the ports will do on this old piston port. I wanted to build a better pipe, do I subtract the covered area from the total exhaust port area? The port timing looks pretty sad in the exhaust calcs.
Don't get piston port engines, is this normal?

 

[Sticker Otis]

OK, no response, had to move on. Not to busy around here so I'll waste a little bandwidth rambling. Made a 080" spacer & .020" gasket. Decked cylinder .100". Top of piston now aligns with bottom of ports at BDC. Going to put it back together with oem pipe to see how that compares to stock. Now I have port & timing specs to build a pipe and compare that to stock. That will give me a base line to compare the next stage to.
Plan is to convert this little LT50 piston port to a reed valve. I built a reed cage intake manifold so I can play with the ports and build another pipe to match. Should be a fun Winter project. The goal is for the really little ones to be able to follow our LT80's around most of the local dunes.

 

[jrider55]

OK, no response, had to move on. Not to busy around here so I'll waste a little bandwidth rambling. Made a 080" spacer & .020" gasket. Decked cylinder .100". Top of piston now aligns with bottom of ports at BDC. Going to put it back together with oem pipe to see how that compares to stock. Now I have port & timing specs to build a pipe and compare that to stock. That will give me a base line to compare the next stage to. Plan is to convert this little LT50 piston port to a reed valve. I built a reed cage intake manifold so I can play with the ports and build another pipe to match. Should be a fun Winter project. The goal is for the really little ones to be able to follow our LT80's around most of the local dunes. View attachment 35610

Dude what’s the set up on that thing? What carb and reed set up is that, also how did it perform after all the work?

 

[jaguar]

piston port works as good as reed valve if the top rpm is no more than 9000. You just gotta get the intake duration correct.

 

[jaguar]

Use this port duration calculator: https://lambretta-images.com/tuningh/port-timing-calculators/

 

[jaguar]

Heres my video comparing the two intake systems: Port timing calculators