Chainsaw Repair

Too bad we cannot take the crank apart and install a new bearing in the bottom of the rod.

I remember when the 670 first came out in the late 1980s when I was logging. I can't remember exactly but the very first  ones had a lighter bottom end or tighter volume crankcase or something and put out real good power compared to the newer models.
One of the Frenchmens ran over one of these first series 670s with his skidder, good thing there was enough muskeg in the ground to prevent the saw from getting totalily crushed. The saw only had about 20 tanks of fuel through it and the only damage was a broken fuel tank, handles, top cover. I bought it for $100.
I ground 4 finger ports into its cylinder, took 60 thou off the bottom of the piston's intake skirt, polished up the exhaust port, gutted the muffler, enlarged the carbs venturi and milled 25 thou off the cylinder base. I sold it to my older brother for $250 as is. My brother won alot of races with that 670 after he fixed it up with new tank etc. In the 10"X10" 3 cuts [1 down 1 up 1down] he was beating the 064s and then the new 066s in the 80cc and over class. Very very strong saw and probably the best saw mod I ever did.
And I kick my ass I didn't keep it for myself.

4 finger ports.............. very interesting ! What configuration/location were they ?

Steve

2 on each side of cylinder bore, each starting from top corner of bottom transfer going up alongside top transfer port ending at the roof level of that port.
Nothing very interesting really......... modders have been doing this since the 1960s if not earlier.