ThunderKart79
Member
A few months back my wife and I bought a Coleman CT200U for our children. When we got the bike it was barely used and was a great introduction to mini bikes for our children. Me being the kind of person who believes there is never enough power well I have been building my son a Tillotson hemi. I started with a 70 mm Tillotson racing block which I bought ceramic bearings than polished the crankshaft and installed a stock length ARC rod with a predictor .570 compression height flat top which brings the piston flush with the top of the block. Then I got a NR mongoose camshaft .272 lift .246 duration then I put true Honda gx160 lifters with a Tillotson hemi head with a 3way valve job polished valves 27 mm intake 25mm exhaust. Ported and polished Bowles and runners. .050 milled off of head and they are 5 mm valve stems. Then the carburetor is a 26mm flat slide nibbi. A header from NR which I took a Footpeg from a bicycle that I bored out a little and welded on the end off header. Believe it or not that made the engine quite down more than an RLV muffler that I have kicking around. Mainly I wanted some kind of muffler to help with tourqe. Also it has a PVL flywheel and a Tillotson coil which is much beefier than the Coleman one with Tailor 8mm wire and NGK boot. Then it has an Inferno fury bully conversion 10 tooth clutch and sprocket 420 chain. I also had to buy a valve notching kit from NR to cut valve reliefs in the piston. According to the compression calculator I used with the stock .045 head gasket it has 10.24:1 and with the .010 head gasket that I will be running it has 11.8:1 compression ratio and I am running 101 octane gas. My wife is scared to death but when I.was 12 I had a brand new KX 80.