Can you plz tell me which tuned pipe should I use with 50 SX? One designed for 46 FX or one designed for 60FX.

Thanks

You'd want to go with the slightly-larger pipe. Mac's makes a 40-60 pipe that should work well, once it's tuned.

CAN someone here please heeeeeelp me....

I got the os 46 FX and after brake-in I got a MACS pretuned muffled pipe... 1 gallon ran fine!

Then today it started well, but then after a few min' the engine started to "studder" in air but not on the ground

I checked the plug (os #8) and it had a curve on the spring inside like this shape --> (

I replaced it with an ENYA #3 (what I had) and it did not work well AT ALL!!!

Infact it did not run I had to rase the idel just to keep it runnig and it was worse than the os plug for sure... I tried playing with the idel/air valve but also no go....

5% wildcat fuel and not too lean on the mix... why am I having problems??????????

Better PLUG maybe ? > if so what kind will do?
*******************************

Any ideas?!

Thanks!

Boaz

We'd like to help, but we're not sure what you mean by "studder".

A deformed glow plug element usually means that the engine's detonating. With a tuned pipe, that means it's not properly-tuned, and is likely a bit on the short side. If the pipe system's too short for the RPM, then the engine will trend lean.

"Pretuned" pipes really aren't tuned. They're usually close, and need to be fine-tuned. The pipe manufacturer can't really know what RPM you'll be running at, so if your engine's running at a different RPM level than the pipe's tuned for, you'll have problems.

Please check to see what RPM range the pipe is tuned for when set up per the instructions, and in what RPM range your engine's running.