Prima pipe on a Roughhouse

[Mrs.Spaceman]

Has anyone put a Prima pipe (the whole thing, not just the muffler) on a Roughhouse? I was thinking about doing it and wondered what kind of improvements I could expect. The dealer told me a noticable increase in acceleration, especially with someone tiny like me. I became suspicious, however, when he told me I could get another 10-12 mph on the top end. It just doesn't seem feasible to me.

[linuxmann]

2 stroke engines rely heavily on exhaust pressure to sustain combustion chamber efficiency. An aftermarket tuned exhaust pipe will send more exhaust back pressure to the combustion chamber during the power stroke, making it produce more power, and it will allow a better flow of burned up exhaust to exit the engine, allowing for an engine that breaths better. This concept will, in theory, allow for more power to be squeezed out of every ounce of fuel/air mix that is put into the motor.

A tuned pipe for a specific motor will increase how efficient it will use the fuel allotted to it, so acceleration and top should increase. However, since basic 2 stroke motors do not have any sort of rev limitations put on them, the improvements will usually cause an increase in the ability of the motor to reach higher rpms, so the motor will have to work at higher revs to attain the desired higher power output. This will put more strain on the motor, but 2 stroke engines have very few moving parts, so this higher stress level won't be too damaging to the motor, because 2 stroke motors are intended for use at high rpms.

Basically, there are many ways to increase the output of a 2 stroke motor, but it will decrease the longevity of the motor. But, a basic cylinder sleeve replacement or slight boring and cylinder replacement will counter these issues. 2 stroke engines rock! They are lightweight and easy to work on, so go nuts! They will surprise you will how capable they are when tuned properly!

[Mrs.Spaceman]

I have the pipe on now. I don't know the exact specs on everything. I got a "kit" that had a lot of the parts in it. Here's what has been done so far:

1. Prima pipe

2. Size 90 jet

3. Performance air filter (replaced whole air box)

4. 6g rollers - trying 9's next week

5. New clutch springs

6. New variator spring, but went back to the old one. Might put it back on after the new rollers are in.

I lost a little on the top end, but I think it's because of the rollers. I was at 55-60 indicated, now it's more like 53-57. Hard to tell since the markings stop at 50. My acceleration is NUTS! I had even lighter rollers in there and had to go up to the 6's because I was almost rear-ending people at stop signs. It's awesome - I'm at 30 by the time I get to the other side of a 4-way stop. I can accelerate UP hills now. My mileage has been horrible lately because of all the tuning and flooring it everywhere.

[ScootLemont]

I lost a little on the top end, but I think it's because of the rollers. I was at 55-60 indicated, now it's more like 53-57. Hard to tell since the markings stop at 50. My acceleration is NUTS! I had even lighter rollers in there and had to go up to the 6's because I was almost rear-ending people at stop signs. It's awesome - I'm at 30 by the time I get to the other side of a 4-way stop. I can accelerate UP hills now. My mileage has been horrible lately because of all the tuning and flooring it everywhere.

Mine is set up like yours (except for the air box)
I bought it that way so I dont know how it was before the mods (dealer did them)
Anyway... I am only getting 70MPG - but I ride it pretty hard - LOTS of hills in my town & I am almost always going up or down one.
+ I have been making some trips to my daughters school & that is over a 400 yard long, 4 lane bridge @ 45mph, up & donwn a hill (read WOT)
My current top end is 49mph (on the gps) 54 indicated.
Keep in mind that I am 210lbs & 6' tall.
I rode a buddy 50 before I bought my modified rattler 50 & it was night & day. I didnt think the buddy 50 would get me up the hills - my modified Rattler 50 has no problem

Sounds like you are enjoying your mods! -
The difference between 70mpg & 90mpg at $4 a gallon is only like 1 cent a mile.