where/what to buy bolt on engine?

[RealliveMD]

some of you have probably followed my thread about my yerfdog 3203. excellent condition. runs 27mph on the streeet no problem. however it bogs on the slight bumps and hills with my 215 but in it. Its a tecumseh 6.5 with a 3/4 shaft. I simply want to take it off and bolt on a faster more powerful engine. don't have time to be fabricating. I'd rather just buy the right parts. however all the bigger engines seem to have a 1 inch which won't fit my comet 30. Any help is a appreciated. and if you're around memphis... I have an engine I'll sale you.

 

[Doc Sprocket]

I believe the point at which most engines go from 3/4" to 1" is in the 8-9hp range. Perhaps you can swap on a slightly larger engine?

What about gearing down a few points and then maxing (or removing) the governor. That will pep it up, and you should be able to maintain the same top end. For argument's sake, what's your final drive ratio and rear tire size?

 

[Blazkowiez]

The harbor freight predator engines are considerably stronger and easy to convert. You may try playing with gearing first. You can change that jackshaft sprocket fairly easily. I will warn you that the back deck on those karts are weak and if you put a much larger engine on without fabrication to enforce the frame it will twist and break.

 

[RealliveMD]

I believe the point at which most engines go from 3/4" to 1" is in the 8-9hp range. Perhaps you can swap on a slightly larger engine?

What about gearing down a few points and then maxing (or removing) the governor. That will pep it up, and you should be able to maintain the same top end. For argument's sake, what's your final drive ratio and rear tire size?

I know it's stock. Yerfdog3203 I think the sprket is 10t and 35t tires 20x10-00-8

 

[RealliveMD]

The harbor freight predator engines are considerably stronger and easy to convert. You may try playing with gearing first. You can change that jackshaft sprocket fairly easily. I will warn you that the back deck on those karts are weak and if you put a much larger engine on without fabrication to enforce the frame it will twist and break.

Is there a how to guide on the freight conversions. I can follow directions fairly well. Let's see I've hooked up a nitrous kit,clutch headers etc on my ta from directions. I once took out a gallbladder after reading a book but that's another story.

 

[r97]

some 8hp engines have 3/4" shafts, i don't know about higher HP than that. Regardless if the higher hp engines have a 3/4" crank (or if you machined the crank down) your comet 30 series is only rated to 8hp.

I would personally buy a 7hp Robin Subaru EX21, more expensive, but quality is top notch. check out the build this guy did,

http://www.kartpowersports.com/yerf-dog-3203.htm

http://www.key-ideas.com/Robin-HiFlow-Intake1.htm

http://www.key-ideas.com/Robin-EX-Engine-Swap.htm

http://www.key-ideas.com/Robin-HiFlow-Intake2.htm

 

[anderkart]

Sounds like you can afford one of these race prepped GX200 engines: http://www.nr-racing.com/gx200motors.htm
Any of these GX200's would bolt right in your kart, you could order a stock fuel tank from them too.

Like R97 mentioned, you'd probably need to upgrade to a 40-series TC to handle the extra power.