49cc's on a Schwinn

FOG

Well-Known Member
Mar 3, 2019
282
615
93
68
In post #155 I mentioned putting holes the back of the piston to feed the boost ports. But one of the PB guys, and what would I do without them, suggested slots instead.

DSCF0941.JPG


I like that a lot better than a couple of holes.
 

FOG

Well-Known Member
Mar 3, 2019
282
615
93
68
As usual I'm goin' off the deep end again by making my own cylinder head. I dunno why. Because I can I guess ... :)

Compression ratio is obviously a big issue but I have this incredible resource at my fingertips we call the internet. I've always wondered what the correct way to calculate CR on a 2 stroke was, and now I know you have to take into account when the exhaust port gets closed.

And there's a calculator for that ...

http://www.torqsoft.net/compression-ratio.html

Luv the net.

Using that a 3cc chamber yields 9.38 to 1. Now I just gotta figure what dimension it takes to make a 3cc chamber. Back to the net ...
 

FOG

Well-Known Member
Mar 3, 2019
282
615
93
68
I found an online calculator for the volume of a dome which led to this ...

40mmCylHead.jpg


All that stuff on the right side is for the wee little cutter I gotta build next. I just kinda eyeballed the 1st one, no drawing, and it won't cut the combustion pocket without runnin' into the squish cut. :( It's good down to a radius of an inch or so but I need to reach in there and cut a 5/8" radius for the combustion pocket.

DSCF0943.JPG


That cutter ain't cuttin" in that far. Too big.
 

JerryAssburger

Active Member
Mar 11, 2017
100
36
28
Salem Oregon
NICE BEAUTIFOLD BUILD, FOG! Excellent choice of color, and yours is the first build I've seen using the Pocket-Bike Motors that are all over Ebay for cheap! Smoother/better that a China Girl? Inquiring Minds want to know! Keep up the amazing work!
 
  • Like
Reactions: Tom from Rubicon