Motor advice - Bad dog Gigantic

Mini Bike & Go-Kart Parts

I’m going to build a bad dog gigantic. I’m not looking for speed as most of the time will be 10 mph or less for off road no trial riding.

I talked to bad dog and he said 8 tooth front because I don’t care about speed. So what motor ? He has a 6.5 Koehler , 10hp tech - this one is spendy.

I also see there are predator, wildcat and a few others.

Any advice would be great.


Well-Known Member
If you want down low power and grunt I'd go the 10hp tecumseh. I wouldn't recommend a Kohler if you want to modify it later. There are still some parts around for the tecumseh.

22" tires 8/60 gearing it'll still hit around 30mph.

I'm running 20" tires with 8/53 gearing on my mm212 pro. It'll rip the front end up and hit 44 with the tillotson singing along. I've climbed some pretty big hills and it wants to bring the front end up.

If I was going to do it I'd go tillotson or ducar. Torque converter. Gear it low like your plan.
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Active Member
You didn't mention if you were going with a TAV or not, highly recommended on big bike like what is being proposed. The Tec 8 or 10hp would also be a good choice and depending where you live a snow blower or tiller may be a good donor and a lot of the snow blowers have the lighting option and electric start. The 9/60 would also be ideal since the odd/even gears make the chain and gears last longer and with the TAV plenty of speed and hill climbing ability.
The only thing that ticks me off with Tillotson is they keep changing/discontinuing their engines and parts. By the time I got my 225 they were already selling their 228, then their 236 popped up shortly after. This would be great and all if they still supported the previous models but the specific parts that differentiate the models become obsolete. This being said, I would go with a Predator 212 and upgrade the cam, valve train and a PVL flywheel. I would also recommend using a torque converter and leave it governed, you'll easily get 10Hp and have a dependable engine that you can get parts for if need be.