Monday, August 4, 2008

Why Can't I Climb Hills With My Go Kart?

I got a question the other day:

"I have a 6.5 hp Robbin engine on my go cart and I put on a hillman 10 teeth centrifical clutch on it, but I have hills all over my place and it wont pull any hills. What clutch should I change to for more torque? I have a 79 tooth sprocket on my drive shaft."

This is like one of those word problems that we used to get when we were in grade school. Our attraction is to the hp, the number of teeth on the sprockets and so forth, when in reality, those are not the real issue....

Here is my response...

Glad you emailed. You are very correct with your go kart system. Typically the one gear ratios systems are very limited on what they can do other than just drive around parking lots or long driveways.

The ideal clutch for off roading is the variable speed belt clutch, or better known as the comet clutch.

Comet themselves sells them, or Northern Tool and supply sells them.

The installation process may be a little tricky, but there are versions that bolt onto your engine, keeping the trickiness to a minimum.

You may have to route your sprocket on your axel to another location, but other than that it will do just the trick.

Reason why it will is that it gives you ratios of 19:1 for pulling up hills, but then automaticallly switched gears so that the ratios are aproaching 1:1.

The difference is this: you have 10 tooth sprocket with a 79 tooth sprocket on the axel. This is a 7.9:1 ratio. A 7.9:1 ratio can only pull so much, and when you get to a hill, you have reach the balance between clutch slipping and the amount of horsepower that your engine puts out. A larger engine might help, but you might be suprised that you would end up with the same situation, a slippling clutch and no movement up the hill.

When you up the ratio to grandma gear 19:1 then you can crank up those hills no problem. The amount of torque that your engine will put to the wheels is about 2 times more than your Hilman clutch can put out.

The units may be a little pricey $180 to $200 dollars, but the end result is what you want, a more useable go kart rough terrain, or hilly areas.

I have an article that brushes the can find it here....

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