2 stroke exhaust question

[05trx400exridr]

i have a question on how the exhaust can be modified on a 2 stoke engine. me and some buddies took an old go-cart frame and re-made half the frame, put some air shocks on it, strengthened the hell outa everything, and put a 2 stoke 2 cylinder 440 rotax snowmobile engine on it. in order to get the large exhaust pipe connected to the engine we had to use about 3 feet of metal exhaust tubing with a couple bends. instead of the exhaust going from the cylinders to the "Y" connecter to the pipe, the exhaust goes from the "Y" connecter to around 3 feet of tubing, and then the pipe. will this hurt the engines performance? im not too worried about losing maybe 5 horse, but if it is gonna ruin the engine we will have to find a different way.

[GPracer2500]

Originally posted by 05trx400exridr
i have a question on how the exhaust can be modified on a 2 stoke engine. me and some buddies took an old go-cart frame and re-made half the frame, put some air shocks on it, strengthened the hell outa everything, and put a 2 stoke 2 cylinder 440 rotax snowmobile engine on it. in order to get the large exhaust pipe connected to the engine we had to use about 3 feet of metal exhaust tubing with a couple bends. instead of the exhaust going from the cylinders to the "Y" connecter to the pipe, the exhaust goes from the "Y" connecter to around 3 feet of tubing, and then the pipe. will this hurt the engines performance? im not too worried about losing maybe 5 horse, but if it is gonna ruin the engine we will have to find a different way.

I'm not completely sure I understand what you've done....But if I am understanding it right than what you've done will completely ruin the function of the exhuast's expansion chamber. The expansion chamber must remain the same distance from the head as it was designed to be in order for it to work.

The function of an exapansion chamber is very closely linked to it's length and distance from the head. The sound waves exiting the exhaust port travel through the exhaust, bounce off the convergence cone at the back of the chamber, and return to the head. The returning sound wave pushes the intake charge (some of which has exited the exhaust port) back into the engine creating the supercharging effect that is the purpose of a two storke exhaust. The length of the exhuast determines the timing of this event. And the timing of this determines at what RPM the "powerband" kicks in. Longer expansion chambers/exhausts move the powerband to lower RPMs. I'd guess that adding 3 feet of tubing would move the powerband so low that the pipe wouldn't retain ANY supercharging effect...

http://www.southernskies.net/page_pics/miss/two-stroke_c.gif

[400eXr1d3rZ]

If you could take a 4 stroke pipe, and customize it to fit a 250r, will it sound like a 2 stroke?

[krt400ex]

Originally posted by 400eXr1d3rZ
If you could take a 4 stroke pipe, and customize it to fit a 250r, will it sound like a 2 stroke?

yes, but u will have absolutly no power. i wouldn't be suprised if the engine doesn't even run

[plkmonster2]

They won't sound exactly the same. They may runt he same RPM, but the exhaust pulses on a 4 stroke are half that of a 2 stroke. A four stroke with a 2 stroke pipe would have to rev 2 times as high to get about the same exhaust tone.

[krt400ex]

Originally posted by plkmonster2
They won't sound exactly the same. They may runt he same RPM, but the exhaust pulses on a 4 stroke are half that of a 2 stroke. A four stroke with a 2 stroke pipe would have to rev 2 times as high to get about the same exhaust tone.

he asked if the 2-stroke will sound the same with a 4-stroke pipe. yes it will