Need help with ratio

[ThaKarter]

Building a kart 2.5x5.5 using 24ft of 1x1in steel tubing. Wheels are 18inx8.5-8. Using a 6.5 hp engine (http://www.harborfreight.com/engine...hv-horizontal-shaft-gas-engine-epa-60363.html ). The kart is not for any intensive purpose at all. Will drive on mainly roads but if it can grass. Would like it to top 20mph. I was planning on using a 1in axle in back but that can still change. I have no idea what clutch or TC to get and with what sprocket. The main goal is to really spend as little as possible. Any thoughts?

 

[HippieHeadShot]

Your set up is almost exactly like what I am building now. I have the same engine. and almost same dimensions (30 x 64 main frame + 12 x 18 front suspension)

I scaled down from 18" to 15" (save money and less stress on the TC) and a straight 5:1 ratio 12t tc gear 60t axle sprocket and I should hit 36 MPH easy. here is the TC I got - took less then a week to arrive.

TC
http://www.ebay.com/itm/331033949001?_trksid=p2060353.m2749.l2649&ssPageName=STRK:MEBIDX:IT

Speed/slip calc (at bottom of page)
http://gokartguru.com/engineering_tool_kit.php

 

[ThaKarter]

How convenient haha. We got the wheels for free so probably gonna just stick to those but sounds like it should definitely be good enough for what we are looking for. About to order it.

Good luck with your project.

 

[HippieHeadShot]

How convenient haha. We got the wheels for free so probably gonna just stick to those but sounds like it should definitely be good enough for what we are looking for. About to order it.

Good luck with your project.

You'll be fine with 18" you might want to bump up to a 6:1 gearing to play it safe. if you run a 12t:72t you be at 5.9:1 for some more torque,with a top speed around 25 - 32 MPH. If your not going to be climbing hills 5:1 should work out just fine for you.

I know you wanted to build on the cheaper side but know this: I'm about 600 bucks in! I did have to buy a welder and tires, so there is $250 off that $600 in your case.

The prices will add up quick on you for all those little parts!
Also: don't worry that the driver pulley doesn't go onto the engine's shaft all the way, that is just how it is. Just be sure you tighten the CRAP out of the bolt that goes into the shaft so it doesn't fly off when driving around!

 

[ThaKarter]

Ah. Didn't realize you posted again. My bad. I ordered the 60t but think Ill order the 72 now. I picked up the motor today though, what do you use to mount it? I think this plate is good: http://www.ebay.com/itm/ENGINE-Moto...TOR-/131285900808?hash=item1e913fde08&vxp=mtr but what do I use to attach the motor to this plate.
Thanks.

 

[chancer]

ahh Bolts? Just kidding but really yeah nuts and bolts. I use grade 8 fine thread and lock nuts. but I don't think you hafto.That plate looks like the typical standard mount plate and will fit perfectly on your HF predator 60363. or most briggs. Personally I find it cheaper to make this plate. Fabrication does not get any easier than that. "The main goal is to really spend as little as possible."

 

[ThaKarter]

Thanks! Wow it's that simple. That's great. Will the motor not vibrate the kart a ton if I attach it just using bolts? If so, any good ways to reduce that?

 

[chancer]

Good vibrations, that is just part of the fun. Some apparently have tried rubber spacers or washers but it never works out.