2 stroke backfires?
 

Hello all,

I've put a 14-6 and a 13-6 on my supertiger 90. I've played
with the low end and high end till my fingers were numb. Why
does it continue to spit and backfire at full throttle? Should i
use a special plug? What fuel is best? I'm using 15 % nitro with
about 18% oil, 4% of that is castor and the rest is klotz. Could
it be backpressure? I fear the pitts muffler i have is too restrictive.

thanks
Craig

2 stroke backfires?
 

Craig, take the carb off and look from the lower end and make sure the spray bar opening is looking down at you. Remove the needle and make sure there's no filings there or obstructions in the spray bar. Then start the process from the beginning according to the instructions. If you suspect the muffler take it off and run it temporarily or try the stock muffler. Warn the neighbors. :) Slimline at one time sold the same muffler for the 60, 75 and 90. It was too restrictive for the 90.

thank you
 

I did as you said. The carb was ok. I put the standard muffler
on and it ran like a champ. I believe the pitts muffler was too
small. It fit, but that didn't matter i guess. It ran and flew great.
Has anyone used a pitts muffler with success? I'm sure you
have, but which one? Again this is a supertiger 90.

Thanks again Vinnie,

craig

Bisson
 

Craig, the Bisson pitts works very well. Also I believe Slimline has a new version called the "large volume" pitts. The one you have will work on the ST .60-.75. Someone else always needs one if you don't. ;)

You're Welcome. :D