Exhaust - 101
Transfers - 119 ----- .
Intake 78
Those are about stock numbers more or less .Except as I recall the transfers are at around 20 after the exhaust .
If I remember right the stock piston to head deck clearance is around 45-46 thou which does better at around 23-26 thou .The exhaust set at 96 would give you a little more blow down which you'll need at higher speeds ,Depends on what you have in mind I suppose .
I'm not sure what to do using a flat top but with a pop up the uppers mildly fingered will give you a better sweep ,really makes a difference .Neat older saw model,my favorite of all the Stihls .If they are done right they will scoot .
Here is the main reason I'm using an 064 piston...
The windows are significantly larger, which will "hopefully" promote better flow thru the lowers.
As for the stock numbers, with .040 out of the squish band, using th 064 piston they were
Exhaust. - 105
Transfers - 123/124
Intake - 67
Of course that's with a real long skirt, due to the 064 being 40mm stroke over the 038's 36mm stroke, so it would had been significantly lower intake with the OEM piston. I just cut the skirt to length on the 64 slug to set the intake. The pin to crown height was nearly .030 taller on the 064 slug as well. Should make all kinds of compression, hopefully not too much though. Easy fix if so, I'll raise the exhaust a bit.
I'm just looking to make a real nice strong work saw, no racer. In my meager findings, the two transfer jugs like less blowdown than the bottom fed type cylinders. I've been wrong before though....
