questions on big block conversion

golfcartjohnny

I've got a late model Marathon gas, that I want to add more power to.
I'm considering either a snowmobile engine, or I have an ATV engine that I've thought about too.
My question is, how many people out there retain the reverse capabilities of these big block carts. Do they just go foreward, or is there some that can still go in reverse. This is for a gas, not electric.
Would anyone out there want to show some pics of the modifications they made to fit the engine in.
The ATV engine is a polaris single cylinder, belt drive, and has the transmission. So I'm thinking this may be the way to go.
How did you run your exhaust? This motor also does not have electric start, and am wondering if theres an electric start kit for them. The motor is either a 250 or up to a 325 cc that came out of a polaris atv.
Any pictures or words of wisdom would be greatly appreciated.

BGW

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slonomo

My question is, how many people out there retain the reverse capabilities of these big block carts. Do they just go foreward, or is there some that can still go in reverse.

It depends on the cart, but a lot do have reverse. The carts that don't run reverse are models that don't have a reverse gear in the transaxle such as the 2 stroke models (G1, Marathon). Most other carts have a reverse gear.

Would anyone out there want to show some pics of the modifications they made to fit the engine in. The ATV engine is a polaris single cylinder, belt drive, and has the transmission. So I'm thinking this may be the way to go.

This is a good choice. I've seen it done many times and they usually work out pretty good. Do a search on "Groundpounder" he did a Yamaha cart with a Polaris engine. Very cool!

How did you run your exhaust?

This is tricky. Usually some cutting a welding involved here.

This motor also does not have electric start, and am wondering if theres an electric start kit for them. The motor is either a 250 or up to a 325 cc that came out of a polaris atv.

Bummer. You will want electric start. You might be able to use the starter/gen if you keep your stock clutch. Other than that you don't have many options except to use an engine that has electric start.


My advice, after doing three engine swaps in the same cart..... Don't use a sled engine, not enough torque and too much rpm. Clone engines are great, easy because of the small size and parts avail. If you are running a lift kit, go with the Vanguard Vtwin, it has the mot torque. In either case you'll need to build an engine cradle and exhaust.

Also, spend the bucks where it counts, on the engine and mount. This will take a lot of guesswork out. Using an atv engine requires using the atv wiring harness and that sometimes is not so simple, and can be very frustrating.

Good luck!

Unforgiven

The atv motor-trans-axle is super easy to do. A lot of measuring, and fitting and measuring. Only hit on the ATV swap is most rear ends are not as wide as a cart, so that's where wheel spacers come in. About $100. One other is heat,.. it's air cooled and has to breath. My fan on the atv hardly ever come on before the swap. I had mine idling in the shop and it cut on and scared the crap out of me.

I've done the Briggs V-twin in a neighbors cart,...it wasn't that bad either. About 6 hours. You will find a blither of knowledge on these pages, and good people to answer your questions.
First pic is my latest build. Second is my neighbors and the third is a CragesList Frankincart that had a motorcycle engine. I don't think it has reverse. Rumor has it that it would do 140mph.

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stuff4mason

Johnny,

A newer Marathon without a forward/reverse switch???

I agree...Don't do the snowmobile engine. If you've got the ATV engine already, do that, if you can find a starter for it. Even if you can't, pulling a rope to get it started won't kill you!! I did a Polaris 500cc scrambler engine in my G16. I love it!! Its perfect for a golf cart build. Belt driven engines are the way to go...If you are interested, you can follow my step by step in my build thread: http://www.buggiesgonewild.com/bike-...0-project.html

Just be prepared for lots of brainstorming. You need to be a 'do it yourselfer' to tackle a project like this, but it is so rewarding when you make it work!!

mudpatrol

on my cushman hawk,i am going to replace the stock rear end with a live axle (go cart style) 1 inch diameter.trans will be from a ploaris atv to retain my cvt and reverse,since i already have that setup and 16 hp vanguard.

TheGDFP

Is this "late-model" the 1980 Marathon from your axle posts?
The Polaris ATV engine mounts differently, but the cylinder will go on. The mellow version 244cc ones peak at 5000 or so, not all that wild. S/G is in the way of the intake port.
E-start was available on most of them.
What, exactly, are the model numbers on the sled and ATV engines, and what cart?

golfcartjohnny

I've looked at the pics you have posted, and noticed the rear clutch on the rear end, is a north south rearend. On mine, the secondary clutch goes east west. maybe I should swap out the rearend for a newer one with north south configuration. Or has anyone done a conversion with a sideways mounted motor?

TheGDFP

They exist. You just have to line up the clutches.

TheGDFP

The stock engine mounts can act as a guide, to mount a twin,





Or, it's pretty easy to double the power of the stock engine.
You'd need to retain the dual-trigger ignition setup or lose reverse.
A 4-stroke would require a rear end with reverse capabilities