custom engine woes and growth, not happy about it but smarter because of it

Discussion in '2-Stroke Engines' started by dchevygod, Aug 5, 2012.

  1. dchevygod

    dchevygod Member

    I built a an lh rc hybrid motor with a used lh bottom end rc 1mm rc stroker crank and a brand new cy 36mm bbk about 3 months ago it was strong. Enough so that i had to get a heavy duty wheel because i kept breaking spokes! Anyways after a good 3 gallons of fuel ran thru it i changed the 219 barrel carb for a new 257 carb as well as put on a rusty old modified s1 that worked but was pointing right at my backside. Shortly after the upgrades it was running great at 35 mph came to a light and it died? "Clutched" i thought it ran out of fuel. Took the head off an was shocked there is a piece of plating from the flywheel side transfer stuck in the top of the piston and a big score above the exhaust port in the cylinder. So i order a zenoah 260 topend kit put it back together same as before with new gaskets after cleaning the cases. Went to fire it for the first time and it snagged the ring in the same place as the cy 290 head? I was so ****ed off but at least the zen cylinder was fine. I was inpatient so i took a geo piston and cut the skirt to match the rc one. This time i took off the s1 and put a wierd can muffler on and its been good so far. My best guess is that the mount for the pipe i made had it in a bind an caused the issue with the first topend and my brand new zen piston. But the good news is that with this setup " lh cases, flywheel, fan cover/pullstart, RC 1mm stroker crank, zen 260piston cylinder, modified zen geo piston, walbro wt257 carb/ADA high flow filter for both air and fuel, unrestricted exhaust can, on an aluminum Motobecane bike with a custom belt drive 14t pinion 272t sheave for the a ratio of 19.43:1. Ive achieved a max speed of 40.4 according to my bike computer, the top speed with the "30cc" first topend it only hit 39.7. It doesn't have a lot of torque but i pedal assist to about 15 mph and it lives at 27mph very happily, but unfortunatly my MBC laws here in my state no faster than 19 or its a moped and faster than 25 its a motorcycle :( ive gotten two tickets to fight in court. I'm confident the first one ill be ok but the second one is not looking very good :( but the bike does do 19 so easily it burns a lot less fuel and it should live a long happy life. I just cant seem to go just over idle it seems like its struggling because of the large pinion gear. im thinking of getting a 12 and 13t to experiment with but i had to make the one i ordered work on a buddies lathe and they aren't cheap.

  2. darwin

    darwin Well-Known Member

    2 tickets to fight I think i'd get a honda 35cc or a rs 35cc and be happy. Tickets suck and aren't cheap. I admire your innovation in the frankenstein motor build and good luck with it. Me personally I need torque to help with the hills, speed is secondary if I can get close to 30mph. Remember its a MAB not a kawi 250.
  3. dchevygod

    dchevygod Member

    Thanks for the comment. Im coming to that conclusion. I need to find someone willing to trade me the small 25 subaru or lehr from a goped propane model but easy to put a gas carb on plus cash for mine cause i have a 45mm clutch housing. The robin 23.5cc has 1.1 hp lol not when im done with it.
    Last edited: Aug 5, 2012