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Shaun's fixing his blowed up Polaris now, so he ain't got time either...
Maybe Chris has time to figure it out.
Wiggs would take too damn long...
Lol - I kinda doubt I'm ever gonna figure out anything about 660s and 390s porting Poulans and Earthquakes!

On the other hand I just got in from the barn after putting the jug back on the Earthquake for my forth try at porting it. I made several of the mistakes listed here and it's been a lazy dog for that. I took too much material from the lower transfers (not terribly but still counterproductive). I had some 46deg of case compression which I think was too much even given the lost case volume. And my port edges were too rounded.

I didn't want to raise the exhaust, so now the intake is at 168 duration and the case compression is at 43. I'll see on the weekend what that did.
 
I did a 066 @ 176 & 174.

It's a tree raper.

Numbers based on pistons, transfers, combustion chambers, case volume, etc. . . Makes saw porting tricky business.

I'm sure there's a relationship there that could be expressed in a cookie-cutter ratio or formula. . . But I ain't smart enough to figure it all out.

There's a Solo out there right now, that seems like it runs on NOS and superman blood. Dang thing is stupid fast, & doesn't even have a cut head.

I'd like to peer into that saw builders head.
 
Well I found a decently clogged fuel filter. Probably was fine until someone mentioned lunch and I realized how hungry I was. Then the average speed jumped up to about 90 mph.
 
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