Heavier Rollers = More Top Speed?

[Jim Moore]

Folks,

I have a 93 Elite SR. I just put in an aftermarket variator and some 7g rollers. It increased my top speed to about 42 mph, but I am wondering two things. First, did the rollers increase my speed, or was it the fact that I left the backing plate off? Second, would heavier rollers get me even more speed. How high can I go with the rollers? DoO they come in different sizes or do the all fit the same?

Thanks in advance. You guys have been a huge help.

[Wheelman-111]

Greetings:

Honda rollers for its 50cc scooters are 16x13mm. Many Aftermarket companies make this size in weights from 3 to 15 grams.

42 MPH from a stock '93 SA50 Elite SR is already very impressive. The stock rollers may have been 9 or 10 grams. Those cause the transmission to "shift up" sooner, and perhaps for that reason the engine wasn't allowed to rev up to the RPM where it makes its best power.

With the 7s, you may or may not have noticed the engine spinning up a little higher during the transition from take-off to your new top speed. With new-found power, it was able to keep accelerating past your previous best speed until the vario maxed.

It sounds like you're already maxing out the variator's "overdrive" capability - since you've recorded 42 MPH with stock gears and power. (this I presume...) Leaving off the o-ring cover might have helped, but going to heavier rollers won't improve your speed if what I've surmised is true.

[Trafficjamz]

If you are going 42 mph with stock gears, that means your engine's rpm is at about 9000-9500 rpm.(depending on the size of your tires)
Stock engines don't rev much higher than that. You have reached the max potential for stock gears.

The weight of the rollers determines, at what RPM to "shift" at.

Think about driving a stick shift car that only has 2 gears

First gear, in our imaginary car, can take you from 0-15 mph before the engine red lines.(can't safely rev any higher)
Second can go 30mph before the rev limit is reached.

Q. Would shifting from first to second gear in this car sooner, change the top speed of the car?

A. No. The cars top speed would still be 30mph because, the rev limit of second gear.

Your top speed change happend because of the deletion of the backing plate.

[Jim Moore]

Thanks guys. I'm starting to get it now. How about a 3.5 inch rear tire (currently 3.0)? Or am I beating a dead horse here without some sort of engine mod?

[Wheelman-111]

Greetings:

Fitting some brands of 3.50 tires can be a challenge. For sure the centerstand needs to be moved/modified/omitted. The crancase itself will rub at the exhaust mounting lug unless you shave it down. Shave it down some more to account for tire "growth" as it spins at high speed. Pirelli SL 90/90s fit without such issues - except maybe the stand.

Frankly, I don't believe stock SE/05 power goes faster than 45 no matter how you gear/variate it. When wind drag force + rolling resistance equals power produced, that's as fast as she's gonna go, Captain. The SA/16 engine may be a bit stronger. Mine was bone-stock inside the transmission with variator and 9:1 gears and it GPS-ed at 49-ish. My stock Aero struggled to make 40 on level ground and calm wind. I didn't feel it had any spare power to gear it up when it was stock. Head downwind or down a steep hill for bragging rights. Everyone else does...