Buddy 50 RPM's?

Lil Buddy · Post by **Lil Buddy** » Thu Jun 12, 2008 3:15 pm

I'm considering getting the Prima exhaust for my 50 and noticed that it was designed to work best at 8500RPM's. Prima says you may want to change your roller weights after adding the pipe. Won't the rollers change the RPM's? I'd like just a touch more top end so I can flow with traffic in the 40MPH zones. My total riding weight is between 170-175lbs. What weights would work best? Should I get sliders or rollers?

jfrost2 · Post by **jfrost2** » Thu Jun 12, 2008 3:42 pm

Not too sure what the stock 50cc rollers are, but anything a gram or two lighter should add some bottom and top end, or just some top end. Sliders will be the best bet. Dr. Pulley from taiwan is a good brand to buy, and easy to get on ebay for around 20-30 dollars a set of 6.

BGK · Post by **BGK** » Thu Jun 12, 2008 5:22 pm

jfrost2 wrote:Not too sure what the stock 50cc rollers are, but anything a gram or two lighter should add some bottom and top end, or just some top end. Sliders will be the best bet. Dr. Pulley from taiwan is a good brand to buy, and easy to get on ebay for around 20-30 dollars a set of 6.

So lighter rollers add both top end bottom end? Please stop posting until you can be helpful.

As for rollers, The maximum RPM of the scooter will increase with the exhaust. But the range where the engine will make usable power will change. When concerning power output, the bottom and top end refer to RPM ranges rather than speed ranges. The bottom end of the RPM range will have less power and the top RPM range will have more power. Adjusting the transmission with lighter weights is like holding it in a lower gear for longer before shifting, when comparing to a manual transmission. It allows for the motor to rev into the higher RPM range, where the new increased power lies, before increasing the gear ratio. So the exhaust gives you more top end (power at higher RPMs) at the expense of bottom end and that's why you have to adjust the transmission to make the rate of gear ratio change avoid the bottom end in favor of the top end. So a few grams lighter in each roller is probably a good place to start. My guess would be about 5.5 grams for someone your weight and the exhaust upgrade alone. But to do it right you'll need a range to really get it spot on. 4.5 to 6.5 in .5 gram increments would be useful to have.

jfrost2 · Post by **jfrost2** » Thu Jun 12, 2008 9:19 pm

Not standard rounded roller weights, those are what you are describing right now. Sliders are different, they add bottom and top end, if you go just a quarter or half a gram down, you dont notice anything different, a whole gram or two can make a noticeable difference.

Standard rollers can take away bottom end but make the top end higher, but not sliders.

BGK · Post by **BGK** » Thu Jun 12, 2008 9:31 pm

jfrost2 wrote:Not standard rounded roller weights, those are what you are describing right now. Sliders are different, they add bottom and top end, if you go just a quarter or half a gram down, you dont notice anything different, a whole gram or two can make a noticeable difference.

Standard rollers can take away bottom end but make the top end higher, but not sliders.

Sliders may have their desired effect, but they obey the same laws of physics and don't change the power output of the engine.