Re: porting a stock e50 jug
oh shit, andrew, didn't realize that was you... sorry for the dick response.
if you want to email me, i can send you a port map. I would strongly suggest reading Jennings 'two stroke tuners handbook' before you touch a grinder, he's already explained it well.
a killer port map for a hi-torq is up 1.5-2 mm on the exhaust port, 1.5mm wider on each side, 2-2.5mm wider on the intake port and 1-2 mm cut off the bottom of the piston. ditch head gaskets and run a hi-comp head. (treats 50cc). Combine with a proma GP and bing/SHA 15 for low 40's and killer torque.
in a nutshell, raising the exhaust port causes the piston to uncover the exhaust port earlier, allowing more gasses to flow out, but making low end torque decrease. it hurts you taking off and accelerating, but you'll go a lot faster. lowering the intake port has the same effect (because it closes in the opposite direction) or you can cut the bottom edge of the piston to do the same thing. Widening any of the ports gives you more power all around, but you run the risk of damaging your rings.
There's a lot more to it that that, but it will get you started. I would reccommend going 1/2 mm at a time and seeing what it does each time. Take an hour on a weekend, pull it apart, grind, put it back together, and see what it does riding around for a week. Play with jetting, timing, etc. You will learn more intuitively by doing this than you will by reading anything, but the books will give you a better idea of the subtleties.
|Graham Motzing||01/04/10 11:21PM|
|Nash .||01/04/10 11:47PM|
|Graham Motzing||01/05/10 03:57PM|
|Ƽɧ▲ɴƹ β||01/05/10 04:51PM|