Box Stock

212 predator

S

Smr#17

Member
Predator with valve springs and 2* flywheel key. Stock carb couldn’t get the float to stop the fuel, kept filling the cylinder fuel of fuel. Cleaned carb Switched float and needle still wouldn’t work,?ran great as long as it didn’t have to idle long. Now I ordered a ruixing carb from box stock Project it runs great till about 4100 then starts sputtering and will slowly gains rpm till about 5300 then clears out and starts pulling good again to 6200. What would cause this? Motor free revs great to 6500rpm on the stand
 
The jets are so small that .001 is big change.Carb could be going fat or lean as rpm increases.A .031 is a starting point for a stock box and pipe or wienie pipe,
 
you haven't given us enough information about your engine what pound springs what camshaft what air cleaner assembly what exhaust system
 
Everything is stock besides springs and flywheel key. Stock airbox and exhaust I’m not sure on what lb springs as they were in it when I got the motor
 
There is a screw on the motor Side carb flange it that a air or fuel screw? I adjusted on it and could make it better but could never get the sputter out of it.
 
Well I don’t have to worry about it no more. Switched the jets out with to original carb. Run up to 5200 without a hiccup but wouldn’t pull anymore rpm, made one more run to double check and it blew up.
 
Not sure still has alittle compression, motor felt tight when tried to pull start it. And was making some clanking noises inside. It was running fine motor made a noise (I thought it threw the chain) and quit. I’ll open it up one day while I’m bored an check it out
 
I destroyed a good flathead that way .
Side cover , crank ,flywheel coil , bolts and carb were the only things left .
 
I just free reved it on the stand to 6500 one time just to see what it would do. I talked to the guy who had the motor before I got it an he said he raced it with 8oz of royal purple in it. So I’m guessing that prob didn’t help much. I run 15oz in the predators 8oz seems awful low
 
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