Robin 2PG modified exhaust...somewhat sucessful!

[stewstang]

Bought this cart a couple years ago with super low compression, faulty oil pump, and no exhaust for $100. Well over the last year or so i have been getting her rebuilt with a .25mm over piston and "tuned in" but since it didnt have the stock muffler it never ran right. Well, my buddy had a pipe pulled off of his rm250 dirt bike and since it was free i decided to give it a shot and weld something together since i have more time than i do money. Don't ridicule the welding because i know i suck at it.



Surprisingly this has helped tremendously! It used to only top out at around 16-17mph (with the governor removed) and now it reaches around 23 or so! Unfortunately it wants to keep climbing in rpm, so i bought a tach and i have seen 5225 a couple times just to see where it goes and i know this is unsafe

https://www.youtube.com/watch?v=QOi_e7zI8lA

Its very loud and obnoxious and matches my group of friends and i very well. Anyway, since we have some "power" can i fit 20 or 22" tall tires on a stock 3 wheel 1984 ezgo?

[my1423]

Cool congratulations.
I like it!!
Would love to try it out.

Technically what you have on there is not the muffler, its an expansion chamber.
It tunes the expansion of gas to scavenge flow of gas out of the engine making flow better or actually suck the gas out of the engine at certain rpms.
The muffler goes on the end , usually just a glass pack.
As long as you dont have any leaks any where, You can tune the pack to be fairly quiet by adding more or less packing and changing the final port size on the end.

You can use the port hole to put a little back pressure on it to prevent it reving too high.

The air cooled rm250 i ran with back in the day pushed 35 hp at 7500 rpm.
The 2pg carb, intake, reeds, and ports limit hp down to probably 18-20hp, being they are all half the size, but the rpms is the killer.
5500 is the max i would push the 2pg. Much higher and possibly a big owwwwww..
I wonder what power it produces at the 5500 rpm. Probably just hitting its big hp curve, too bad its dangerous.

[clr.R4tch3t]

I have a feeling you can push these carts to a much higher RPM than factory suggests. I am also going to play with an expansion chamber on my cart.. I have a 250 and a 125 pipe. Once I crunch the numbers I will add it to my engine build thread. That piston should hold up to 8k+ RPM. If you don't want to push your cart that hard, that is fine.. but I will be up in the 6k range when I am finished. If it doesn't explode. Hahaha

[stewstang]

Ballsy...BUT i like it! had mine to 5750 today since i adjusted the cable, i may bring it back a bit or just send it!