There have been a few threads recently on the Duropower engines. I have two of them with the gearboxes designed for scooters/skateboards and while they run great the metal quality is somewhat suspect. I have been looking at their 50cc 4 stroke as a possibility for the 1/3 scale pup. I can't seem to find any info on this engine. Has anyone seen one? It looks like it might be a scaled up version of a Honda GX series, inverted mounting is the most important thing to me.

http://www.duropower.com/item.asp?PID=88&FID=3&level=1

I just ordered the 52cc 2cycle for the price $79 I can live with the casting metal they use.
Ken

I think you will end up OK. Mine on the skateboards are about 3 years old but never got more than a few hours usage due to constant breakage of various components. The hub cracked where the gear mounted (on the wheel) the brake and throttle handles snapped, the cables stuck, and some lugs on the engines and gearboxes have broken off with or without touching them causing some gear oil leakage but they still held together. I would just be careful about the mounting lugs cracking, that is why I bring this up. I am willing to give this 50cc 4 stroke a try myself if it can be mounted inverted or if it will fit within the cowl upright if it cannot be mounted inverted. It is hard to tell from the dimensions because I am not sure if that fuel tank on top is included in the measurement of 14 inches or not, or if they include the tank but not the filler cap etc.

After allot of web surfing last night it seems that this is a clone of the Honda 50cc engine. Now, Honda specs this engine at 2.5 Hp and Duropower specs it at 1.5. The bore, stroke, CR etc. are identical as are all the other numbers so I bet that the HP is the same. The problem here is the weight, the engine is only going to loose about 2Lbs of extras and that leaves a 10Lb engine, the Stihl 65cc looks like the better option.