no compression

[zendiecut]

I know, bra...
Just being lazy.

Thanks.

 

[Norman]

on one of my posts I show how to make a pattern of the base gasket if you go and look you might find it I could go look and give you the link but I'm being lazy today myself.

http://motorbicycling.com/f39/motorized-bicycle-engine-top-end-rebuild-297.html
look at permalink #12 how to make a base gasket pattern
Guess I'm not that lazy after all?
Norman

 

[zendiecut]

Well, I put the original head back on the engine and the thing runs much better. Stupid me. I got the engine with a broken fin, called the dealer and he sent me a new one. However, the one he sent was for the 66/80cc engine. Too big of a cavity in the head. Created much too low compression. I put the original back on and the thing is slowly improving (just breaking it in). Ordered a slant head and can't wait for it to come in. Should improve even more and produce more power. I saw a guy that fill welded his head to reduce the head space. Doing the same thing the slant head does. Reduce head space!! Great idea. BTW, the cylinder and piston are still mounted backwards to put the exhaust out the back. Works and looks great. On a Rat Fink Chopper too. Real cool.

 

[stv1jzgte]

Thanks. But I studied this ting pretty good before I spun it. The cylinder walls and ports on the bottom sides are symetric. The gas comes into the underside of the piston at the top of the stroke and is compressed in the crankcase when the piston comes down. The gas then goes up from the crankcase through the side channels (one on each side) and into the cylinder through the ports on the sides of the cylinder walls.

Unless there are reed valves inside the crankcase (I highly doubt it), I don't see how it matters what direction the head is in. I just read that these angines only have a compression ratio of about 6 or 7:1. That's pretty small. Much smaller than say a lawn mowers, which will blow your thumb right off the plug hole.

But I'll consider turning it back around and see if it does matter. Thanks.

Turning the jug and just bolting it back on will not work, look again the transfer ports dont line up not even close. Yes air fuel mixture will pass through but it will run nowhere near as good as the otherway.
Norm?

Sorry Just read the hole thread disergard my dribble.