rearenginekarts.com

so far It seems ive got screwed with and cant find anything that I need. I have a mcculloch 300 (older saw) that my mom bought for ten bucks. it was beaaaaaaaaat though which is considerable seeing as how its like 50 years old. anyways I decided to through in on this old pocket bike frame I had layin around made my own mounts(fits perfect). but then knowing me I take it apart thinkin it runs now but it wont for long so i start to rebuild the engine clean it up ect. goodthing bc the crankshaft is toast along with both the main bearings. so i bought the new shaft and bearing now im stumped. way different demensions then the stock and doesnt even have a key hole on the clutch side. someone told me its accually a real strong kart shaft. but i cant seem to find a damn thing on it. the #s read 89221. please any help and advise would be greatly appriciated.

With out going to a lot of throuble the crank part no 89221 is out of a PM105 so possibly the part no 89222 is similier and these are super series engines with a fixed head and no boost ports now i would say that the old 300 is of the standard series hence i doubt that they would be suitabe for the old 300 ................. am i wrong fellas ...............

The correct crank is part no 60313a with the rod being part no 47903.

Mc Bob.

your best bet is to buy a ebay chainsaw parts motor or a swap meet lawn sale one.
then you'll be able to harvest many of the needed parts.
but if you insist on rehabbing this one.

first did you just pry apart your motor when you broke it down?
if so you have bigger problems than worn bearings.
the motor bearing are set with a heat expansion press fit.
that means these motors must be taken apart and re-assembled with heating in an oven 250 degrees or so.
both when you break them down and re-assemble.
second why is the crank beat?
details would help.
almost every saw i've taken apart has had pretty good to excellent cranks.
so since these use roller bearings on the con rod ,the shaft itself might be o.k.
if not there are two styles of mcculloch motors.
the short shaft mc10 -101 series and the 91 series in karter terms.
yours is the mc 7-91 series in kart motors and just about any 200-300 series will fit.

2nd go to mcbobs site and you can read up on parts interchanges and other neat facts about your motor without a lot of tedious searching.
also the main bearings and seals are available new.
search this site and there will be threads discussing this.
but as i said before there's alot of the chain saw motors around.
for your purposes you'd be well served to just buy another and start over.
d