I have three of these, two marked with "40 P" on the bypass, one without the "P". All three came to me as r/c versions with carburetors. The exhaust timing seems different on all 3. In one, the liner is cut so that the exhaust slots are centered in the stack, the second has the upper edge of the slots at the top of the stack, the third's slots project above the stack a bit. The net effect is that I think the exhaust timing is different on each of the three engines, as the height of the milled slots seems to be the same, but their location sure doesn't appear to be so. Any suggestions as to what I have, and how best to take advantage of it(or minimize its negative characteristics)? I have not had the third apart for overhaul yet, but it seems as if this one has one ball bearing at the front of the counterweight and a bushed case.
Any students of the variations among these engines able to comment?
Many thanks.
Peter Havriluk