I found a site that sells engines for scooters/gocarts...

They have a nice little 47cc engine for only $135.00
and a 49cc engine for $149.00
even a 36cc for only $124.00
and a few more

[link=http://store2.partsforscooters.com/s.nl/sc.2/category.19/.f]Check it out.[/link]

I bought two gas skateboards about 2 years ago and they sent me a replacement engine because the starter spring failed on the included one (go figure). So I have a spare 49cc in the box. It is one heavy monster but it does have the gear reduction box and such on it. Even with it cleaned up I would never consider using it. The engine, as all of those chinese scooter types are, is made from the worst materials you can imagine. The crankcase is made from a brittle pot metal that splits and cracks around screw holes and cannot be tapped or machined in any way.

You would be better off to do a chainsaw engine. Get a reconditioned Poulan or Homelite in the 46-50 cc size. Echo would be fine too, same as a BME if you could find one.
Z

Husky chain saw models 272 288 2100 and the 394 ( 72. 88, 100 and 94cc's) are very easy to convert and are quite readily available used. The best part is the output shaft has the same taper as the zenoah g62 so fitting an ignition/prop adaptor is an off the shelf item. i ran a 2100 ( 100cc) in a Miles Reed Weeks solution pitts bipe 68" WS this engine was absolutely ME proof

I have the 49cc shown on that page,cost me £30, its gonna be quite an easy conversion I think when get round to it, all the heavy bits strip of easy, the CArb looks a bit iffy tho

here it is so far...............................

But as others have said it seems poor quality materials, not up to most chainsaw standards for sure

Personaly I am converting a Poulan 42cc.. But I came across this site and thought that those looking for an engine to convert could benefit from it..

But I see what your saying... the crankcases do look to be made of some cheap alloy instead of aluminum like most chainsaw engines....

Anyway I attached a pic of the engine I'm converting ...

>>42cc Poulan Pro
>>CH Ignition on order
>>Pits muffler on order
>>12.5mm WalBro carb
>>Velocity stack on order
>>I am also going to have a few of the cooling fins machined down (just a little) to try to save a couple ounces.

Hi,
Don't spend money on fin machining until you put it into a plane. You may find that you need the weight anyway to balance. If you trim fins, do the ones closest to the crankcase. Look at a BME 50.

Dave