Yamaha Kart Engines Kt100s Manual
I didnt build that DIY kart starter in my pic, I just borrowed it from a buddy until I found a used Burris kart starter I bought for $100. The DIY kart starter in my pic above was made from one of the 12-volt ford starters the 272/292/312cid engines used in the mid to late 1950's. Those starter motors work best as DIY kart starters because they have a long output shaft. They look like the pic at this link: The tricky part to building your own kart starter is they really need some type of one-way bearing/clutch or ratcheting device installed in the shaft for safety reasons.
Otherwise if you rev the engine (before pulling the starter out) you'll end up spinning the starters Armature too fast where it could explode/seize up. All factory made kart starters come with this one-way bearing or ratchet feature. Comet sells a part called: ' Starter Ratchet Driver - 11' Long, Specify.500 or.510 starter shaft size and Right Hand or Left Hand rotation starter' about halfway down the page at this link: It has a ratcheting feature built in. You'd want a Right-hand model for a KT100 kart.
(the left hand model would just be needed for the left engine of a dual engine kart) You'd need to measure the shaft diamiter of your starter to make sure that part would fit. Edit: Another issue with using many automotive starters is they spin the wrong direction for a Right-hand type kart starter, but you can usually make them spin the other direction by simply reversing the brushes.
This usually requires extending the brushes wire leads so they'll be long enough to reach over to the opposite sides. I started it with a drill seemed to work fine for now might want to build my own using anders idea. And I live in Toronto.
Problem now is once you give it gas the 1/2 bit that goes to the crank unscrews itself and falls off (the back tires never move unless the kart is on stands) no clue how to fix. Engine runs great tho does anyone know what gas il mix I should use I started with 25:1 but it's giving blue smoke so I guess it needs more gas Btw what I did to start it was use a hammer drill with the hammer setting off turned over easily Btw thanks everyone for the tremendous help. Using your drill (with the hammer feature turned off) Is fine. If you left the hammer feature switched on, or tried to use an Impact gun, you could end up breaking the crank snout off.
That bolt in your crank is unscrewing because you need some type of one-way clutch like I sugested before. If that bolt hadn't unscrewed when you reved the engine, your drill would have started spinning at very high speeds and probably broke your wrist and/or fingers. Lots of guys (including me) have have had wrist injuries trying to use drills or kart starters that dont have some type of one-way clutch device installed. You could cut the drive end of a 3/8' extension off, and then grind the extensions end to a triangle shape so it would fit/lock into the chuck of any 3/8 drill. Then simply plug in a 3/8' drive ratcheting adaptor and Allen head socket like my pics above.
The ratcheting adaptor would work fine as your one-way clutch, If you shop around you could probably find one for under $20. Here's a link to a used Snap-on brand adaptor selling on ebayca: Most guys use a 20:1 premix ratio with KT100 engines. Quite a few report this engine makes even more power using a 16:1 premix ratio because it increases ring-seal.
If you use less oil than a 20:1 ratio, there's a very good chance you'll seize your engine. Make sure you use 2-cycle premix oil, not just regular motor oil. Its completely normal for KT100 engines to smoke a lot, so get used to it. One way to start it is to get rid of the clutch (you'll need a sprocket) and connect it as direct drive. Then you can either push start it or put it on a stand and use a strap to pull the rear wheels around. That's how we did it before clutches. To push start: Stand on the engine side, right hand on the stearing wheel, Pickup the kart by the read crash bar, run a couple of steps then drop it and keep pushing by moving your left hand on the seat back.
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Yamaha Kart Engine Kt100s Manual
When the engine pops step into the seat with you left foot and get your right foot to the throttle. If it goes, sit down and drive. Or just get someone else to push. A car starter motor, usually from a Toyota Camrey is what is used mostly these days. Starter motors have an overrun mechanism so that when the engine starts the bolt won't get unscrewed and your arm doesn't get ripped off. If you tighten the bolt up too tight all you will do is break your drill or your arm when the engine fires, and you'll never get the bolt off again because you tightened it too much.
What brand of 2-stroke oil did you use? If you feed a few inches of clean rope down through the spark plug hole, It'll stop the piston from moving up so you can tighten that bolt. I have seen quite alot of pinched rings using that method, well two actually. The rope can push the piston ring groove closed. Best to get a proper piston stop which screws in the plug hole and dont over do it on the torque, as you can get a lot of leverage doing damage there. I hope that saves a few KT's.and some cash and grief.