Mine doesnt have the slant head it just has the straight plug head which I have read is actually lower compression than the slant but I dont know if this is fact or fiction.
yeah mine will rev like crazy too, I have run it on 16-25 mile trips almost wide open the entire way and it stilljust keeps on going with 1200 miles on it now, this has been the best of the engines I've had as for as needing any tinkering because I have basically done ZERO tinkering on this one aftre I got the carb tuned I have just run the dawg out of it when I ride it and it never has let me down.....Opti 2 is holding it together IMHO plus it just so happens to be a well put together engine with the acception that it is the worse balanced of the 4 I have, this thing will numb you from head to toe if it is run over 28-30 MPH for very long, I plan to put a 36 or 38T sprocket on the wheel to get the revs down to comfortable at around the 28-30 mph range, it runs very smoothe @ 25-26 MPH but above that and let the vibrations beggin.LOL!
Originally Posted by chrisme
I had one of those 6mm stud 66cc engines. Tough little beast! I modded that heavily. Shaved slant head, tuned, porting, custom intake, etc, etc. It hit 40 on flat ground with a stock rear sprocket. Spinning crazy high revs. It finally died...