Drivetrain question

[SuperPro]

My friend and i recently got a free kart, the motor was blown so we need a new one. We bought a 6.5hp briggs (900 series) with a regular centrifugal clutch and that setup didnt move the kart with no one riding on it, however we threw it on a minibike and it worked just fine with a 300lb person riding it.

i need your opinions, would a torque converter cure this problem with the same engine, or do i need a bigger engine? we have a budget of $400-500.

I found a 13hp lifan engine at a decent price, and these torque converters http://gokartsusa.com/tav301bore4041chain.aspx . but i cant afford to spend money on something that may not work.

Thanks alot!

 

[devino246]

what was you gear ratio & tire size on the kart? a 6.5 hp should have no problem moving a kart.

 

[solomon]

Sounds like the gearing on your kart was wayy off. How many teeth are on the sprocket of the clutch and the go kart? What size are the tires? A torque Converter is the best investment for a standard kart with a standard small engine like your 6.5 HP. Not sure which Torque Converter would be best but I know a fairly common and easily mountable one is the TAV2. I believe it goes for around $250.

 

[SuperPro]

the clutch has 10 teeth, and the axle sprocket has at least 60, its almost as big as the tire, which is size 22x11x8, the actual height i havent measured but its about the size of a riding mower back tire.
the kart i believe is a manco dingo, i dont know the model.

 

[SuperPro]

the clutch just smoked even with no one on it, it would go if i pushed it but that doesnt do me any good.

 

[solomon]

Sounds like the tires are a bit to big for the gear ratio. You say at least 60T, well we need the exact amount. 6:1 gear ratio just wont cut it for that large of tires.

 

[SuperPro]

alright so i did a count on the axle sprocket and came up with 72-73 teeth

 

[solomon]

Hmm gear ratio is roughly 7:1 and it still has trouble. Might want to go down a few sizes in the rear tires. Go with a 15-17" rear tire.

 

[SuperPro]

i just tried rolling it around, one of the tires if pretty much flat and the other is low, could that be enough to not let it take off?
how much take off power would a torque converter really add over a clutch, would it be enough to get a 6.5hp to move the kart and a 300lb rider?

thanks again

 

[Kenny_McCormic]

The Dingo is very heavy, a sled engine+trans would push it good.

 

[solomon]

The low tires can be an issue but it should move. The torque Converter isnt going to help until you the gear ratio right. If the rear end is lifted up does everything move smoothly? Also do to the weight you really need to change the gear ratio. Go for 8:1 or 9:1. You can get a jack shaft,larger axle sprocket, or smaller tires.