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Pit Kart! (Pit Bike engine on a Go Kart Chassis)
Pit Kart! (Pit Bike engine on a Go Kart Chassis)
Pit kart
Published by Yiasoumi
31-03-2017
Talking Pit Kart! (Pit Bike engine on a Go Kart Chassis)

Hello!
I'm going to explain everything I can about my project and the creation of the go kart (sorry for the long windedness .

So basically for my college project this year you have to find a solution to a problem you are experiencing, so my idea was to put a faster engine in a go kart frame, as most karts when you go karting with your friends are quite slow especially when you are the larger one out of your friend group haha.

Originally I had planned to put my CR 85 engine in the kart, as this has been done in the past by other people, but alas my mother wouldn't allow it as me and my little brother share the bike, However I did decide to put the 110cc pit bike engine in the kart.

The 110cc engine itself was originally out of a quad bike, (had starter motor and few other extra bits and bobs on it), the engine feels more torquey than other pit bikes? not too sure if this is to do with low gearing in the engine itself? or is that out of this engines league haha, I imagine they're all standard.

Anyway back to the kart, I faced a few problems along the way, especially in the designing stage, with the engine mounts and how I would go about attaching the engine to the chassis without damaging the chassis and also how I could over come changing gear as the engine would be mounted behind me, finding somewhere to mount the clutch lever / making my own, and finding a 420 / 428 pitch sprocket to pit the 50mm rear axle as normal karts usually run a 219 pitch which is inconvenient.

I had a rough idea in my head what I wanted it to look like and how Id go about solving all of these problems.
I drew a few sketches and drawings of the kart, the different types of mounts I could use, and different gear levers as well. (see link below)

I bought a rolling chassis off of eBay, all that was needed for it was an engine obviously haha, a new seat and the brakes needed a service. Once i picked the chassis up I bought a new tillet carbon kevlar seat Off of eBay once again, very cheap haha.

Once fitted I set about servicing the brakes, new pads and a new disk were bought. Turned out the plunger in the master cylinder was rubbing as if it was too big for the cylinder? not too sure why I'm not very technical with these sort of things, but with a bit of sand paper I rubbed down the burred edges and it worked like a dream.

I had to mount the fuel tank behind the seat, as the carburettor is gravity fed and a fuel pump just was not an option for me, however this was a very simple fix and works like a dream.

When mounting the clutch lever, I had used the lever off of the donor pit bike, I bolted it to the holes in the steering wheel so it was easy access, unfortunately I couldn't mount it behind the wheel because it would get in the way of the nose cone. I used a mountain bike gear cable and sleeve for the clutch cable as I couldn't locate a 2m clutch cable on eBay for a pit bike, I also did the same for the throttle cable which fed into the top of the carb.

When mounting the pit bike engine to the chassis, I bought two engine mounts for a bog standard kart which bolted around the chassis and then these mounts had two bolts sticking out the top which I then mounted a mild steel box tube per mount, and then bolted the steel pit bike sump guard too the tubing then obviously mounted the engine onto the guard.
Using the Chinese annoy ones here was not an option as the forces being put through the guard would be stupid so it has to be strong, as I had learnt from my first mistake, the guard I bought was meant for a pit bike engine without a starter motor, and alas mine had a starter motor, so I thought it would be a good idea to cut down the sump guard to fit around motor, it worked for about 5 minutes until the engine ripped from the mount which ended in disaster! (see photos) back to square one I went.

Sadly the only option was to grind away where the starter motor mounted onto on the engine casing, luckily enough the starter motor didn't work anyway so I wasn't too fussed and alas the engine was securely mounted to the frame! now all that was left was to fit the side pods, get the engine started and just tidy the small bits and bobs up, fix rattles, and stop any loose parts falling off!

To stop the chassis twisting due to the unbalanced heavy weight from the engine, I purchased front and rear torsion bars to help stiffen the frame, hopefully this should help when out on track.

Luckily enough I found a 428 pitch sprocket on eBay which fits a 50mm rear axle, so I bought a 428 chain and and a 428 front sprocket for the engine, then split the chain in half and put it on the kart! I am a bit unsure of the gear ratio at the moment, I believe I'm running a 16 front and 24 rear, but because of the small wheels the acceleration you would gain from small wheels and the power of the engine I believe it should average with top speed from the small sprockets, reason for such a small rear sprocket is because i couldn't fit a large rear one one without it scraping on the floor, I also couldn't locate a larger one on eBay haha.

I have probably missed a few things out, but if you have any questions, or any advice please feel free to ask away! Bearing in mind I am only 19 and have limited knowledge on go karts I think i have been pretty successful
I have also attached a google drive link where you will find a few videos of the kart and a few pictures .

https://drive.google.com/drive/folde...Tg?usp=sharing
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