Needles on old mugen mr-12
 

Have older mr-12 not the new one,one that came in kits I think,not the mt-12 either.Is the hsn 4 turns,and the lsn 3.5?How many shims should it have to run with 20 %.What are some plug reccomendations,I run a cold nova plug now.

I always liked that motor. Not sure about the factory needle settings but it's pretty much the same carb as all the other Nova .12's.

Try a hotter plug. I liked 6's unless it got chilly then I would break out the 5's.

I live in fla. so its always hot,so i guess ill try a 5?Should i change the shim to a .2 compared to the .3 in it?Never had such trouble getting a motor to run right ,have had quite a few novas before as well.Got this motor from someone who said it was brand new???No box or instructions though??

It should run fine on 20% with stock head clearance.