49cc's on a Schwinn

[FOG]

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.

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

 

[indian22]

FOG nice work. I've used alumi-weld rod to build up aluminum cases rarher than epoxy and it held up well. Though I know that many use epoxy to stuff cases with good result I'm not that trusting.

Rick C.

 

[indian22]

Slots are fine and look nice, though I use one big honking hole.

Rick C.

 

[FOG]

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]

I found an online calculator for the volume of a dome which led to this ...

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.

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

 

[FOG]

Here it is. On paper everything I need to know ... I hope!

Now I just gotta put in metal.

 

[FOG]

This has been an "if first you don't succeed" deal. But I got it.

That's just a practice piece but it looks like a combustion chamber to me.

 

[JerryAssburger]

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!