Jiffy Legend, after market muffler or pipe?

[blufloyd]

Anybody change their exhaust to a tuned pipe of muffler to get better performance?
If so where do I look for one?

[dkfry]

The idea crossed my mind also. I havn't found anything yet. I actually designed a muffler in my cad/cam software but never got around to machining it. For now I enlarged the outlet hole slightly in my stock muffler. A pipe would bring a lot more power to the table but it should be custom made for the engine size and wrapped around the engine so it isn't too bulky.

[CMMahy]

Maybe something like this? Probably have to cut/weld your own flange on to save costs.

http://www.needforspeedhobbies.com/zenoahenginetunepipes.htm

The hard part I think would be getting the added air and fuel into the engine. Remember, air in has to = air out.  I've toyed with the idea when I saw how crude the exhaust was on my JIffy STX, but the lack of adjustability in the carb is whats keeping my fingers out of there, for now. I suppose you could bore it out and (hopefully) switch to larger jets to get more air and fuel in. Seem to remember a previous post by someone who had ported the cylinder, shave the head and was running race fuel, but haven't got the time to search for it.

Good Luck!

[dkfry]

Those pipes are designed for 22.5-26cc Zenoahs, Quickdraw, J&G and etc engines at up to 20k rpm loaded. The 2hp Jiffy is 49cc and needs a pipe for it displacement and operating rpm range. Maybe a pipe for a similar displacement Goped engine, I need to look into it further.

I agree if you touch the exhaust side with a pipe or even a decent muffler the carb has to be dealt with because on the later 2hp engines they are fixed needle carbs.

[blufloyd]

Think mine is a 3hp used to be 10 inch cut.

[CMMahy]

Maybe the pipe off an old 50cc MX bike, splice a few inches of tube into the widest part of the pipe, drop the RPM operating range down a bit. Was doing some looking at what they use on the chainsaws they race in the lumberjack competitions and they use old 125 Motocross bike pipes that they adapt.