The Engine:
SmC-Racing 70cc Puch E50 "Powered by Smitty"
Specs:
70cc Athena, 2-ring, reed valve "kit", high-compression 70cc cylinder head, Competition 'stuffed' crankshaft, SmC-Racing
SE Mikuni carb, Proma Circuit expansion chamber exhaust. 3-shoe clutch.
Separating the Best from the rest:
Crankcase port-matched, and greatly enhanced, transfer ports polished, redirected (for optimal flow) and roughened in certain
locations. Intake manifold cleaned-up, volume increased, roughened, and enhanced. Piston window smoothed. Exhaust port
polished. Special Edition Mikuni carb, bored, funneled, and polished. All brand-new, high quality bearings, seals and gaskets.
Crankcase sealed with Yamabond (allowed to cure before assembly). Crankshaft rotated while tightening cylinder head, to ensure
proper and smooth piston centering in cylinder bore. Top-end lubricated with Duralube after assembly and before cranking.
Even I have to admit that the Athena “kit” for Puch was somewhat of a challenge. Lots of details had to be
taken care of, such as casting flashing in the piston window, the intake manifold took lots of time and work to increase its
volume and direction, and the engine case transfer ports took a great deal of time and work to get to match and flow to my
satisfaction. I also spent a lot of time reworking a Mikuni carburetor to my satisfaction, to be used on this engine.
I do not recommend the Athena 70cc reed valve kit as a “bolt-on” !!! There were several areas that really needed
to be cleaned-up, and evened out, before I could even begin my port-work. The transfer ports in the crankcase (along with
the base gasket) desperately need to be matched to the base of the cylinder as well.
A lot of money, time, and work was put into this engine, but I feel really confident that she’ll be the beast
I’ve been wanting to build … hehehe ;^)
UPDATE 5/24/06:
I've found the 64cc Polini's competition here folks! This monster screams like a demon. It sounds
like the combination of an over-grown chainsaw on steroids and a fist full of pissed-off bees in a tin can. Plenty
of power, and it just keeps climbing. I wish I knew where a dyno was I could hook this 'ped to!!!
Presently, to ride it on the street, I have it geared at 16t/40t, and could still to go on up some more! To
find out what the top-speed on it is, I plan to run 18t/36t, and then do a radar-run.
This ain't your GranDad's Moped!!! This one's "Powered by Smitty"!