157QMJ variator wieghts?

[gitsum]

I have a Tomos Nitro 150 (made by SYM). The current weights are 13 gram rollers. The scooter is mostly stock, I just retuned the air screw a bit and increased the main jet from a #108 to a #110, removed and blocked of the PAIR junk.

This scooter really hauls @ss for a 150cc air cooled engine. Riding two-up (combined weight 260 lbs) it tops out at an indicated 65 mph and holds long grades at 50+ mph, acceleration is very spirited up to 45 - 50 mph on level ground. Accelerating at WOT the rpms are 6800, and at a steady indicated 55 mph (3/4 throttle) they settle down to 6400. I have a CHT gauge installed and temps usually run 310 f - 350 f (on a warm day), at cruising speed (indicated 50 -55 mph) and a long grade at WOT will push the temp to 370 - 375 f for a short time. The speedometer is about 5% optimistic. Averaging 90 mpg so far.

I'm really happy with the overall performance and feel like the CVT tuning is pretty close to optimum. I want to switch to Dr. Pulley sliders and keep the rpms close to the same, or maybe just a couple of hundred rpms higher. I've used Dr. Pulley sliders in my last 5 or 6 scooters and like the overall performance and extra longevity. Should I try 13 gram (same as stock) or 14 gram? I know a lot of GY6 guys like 12 grams, but I am afraid it might raise the rpms to 7500 or above and push me above the maximum torque band during WOT acceleration? This engine pulls good at 6800 rpms and really does well on hills, I don't want to compromise that or have the engine spinning at higher speeds with no improvement in acceleration.

My last 5 scooters were: SYM HD 200, Honda Elite 110, Yamaha C3, SYM DD50 two-stroke, Oliver City CPI 50cc two-stroke. All of them were modded and had the variator weights tuned, but I don't have much experience with the more common GY6 157QMJ.

Any opinions or advice would be greatly appreciated.

[techie610]

Sounds like its doing pretty good as is. But I would probably got to 14s and test it.
Sliders are much better than rollers, and react a bit differently. Get some 14 sliders, run it for a few miles. Pay attention to the ACCL and RPMs. Also, take into account the reaction time when letting on and off the gas.

When I went to sliders for the first time, riding at .25 throttle and then imeadiately going to WOT, the ACCL and was impressive.

On a side note: I wouldnt use a rubber belt. Kevlar runs and reacts much better and faster.

[gitsum]

Thanks for the info, I guess 14 grams is a good place to start. I have a digital scale, so if needed I can remove a little material from the inner brass collar and reduce them to 13.5 or even 13 grams. They cost $30 shipped a set and I didn't want to buy them twice or even three times. Not sure why, but the 12 gram sliders are only $19.95 shipped.

[techie610]

@> gitsum : What have you come up with?

[gitsum]

Originally Posted by techie610

@> gitsum : What have you come up with?

The sliders are supposed to get here tomorrow. I will install them right away and take a short test ride.

[gitsum]

The rpm's dropped a couple of hundred during acceleration. So I drilled the centers out for 13.5 grams apiece. I'll report back after a test ride.

[gitsum]

13.5 grams did the trick. Rpm's are close to stock and acceleration feels a bit smoother and slightly improved.

[techie610]

Good to hear.
If you have any other questions or comments, feel free to ask and post!

[ltdHPP]

Don't be afraid to try 12g sliders, you may be very pleased!
I tried 13g rollers (stock), 12g rollers, 10g rollers, 8g sliders, 12g sliders, then 10g sliders...
9g worth of sliders wound up being my sweet spot, but me and the scooter both add 100lb to the norm. Plus every ride here is uphill both ways....

[gitsum]

Originally Posted by ltdHPP

Don't be afraid to try 12g sliders, you may be very pleased!
I tried 13g rollers (stock), 12g rollers, 10g rollers, 8g sliders, 12g sliders, then 10g sliders...
9g worth of sliders wound up being my sweet spot, but me and the scooter both add 100lb to the norm. Plus every ride here is uphill both ways....

Do you know what your engine rpm's are accelerating at WOT and also at top speed?

[techie610]

Whats your top speed with the new sliders?
And before them?

[ltdHPP]

Originally Posted by gitsum

Do you know what your engine rpm's are accelerating at WOT and also at top speed?

Currently with 9g (3x8g and 3x10g) WOT acceleration at low speed is about 5,500 to 6,500 rpm depending on grade. Once I am up to 35-50mph (on flat) WOT is around 6,500 to 7,500. Top speed is 60-65, depending how much non-uphill grade is in front of me Rpms at top speed are about 8k and will creep up slowly, again depending what grade is ahead of me.
This current setup is also the only setup I seemed to notice an up-shift on acceleration and a down-shift when climbing a steep hill at WOT.

With 8g sliders rpms were way up, accelerating in the 7k range and top-speed pushing towards 9k... this is why I went back heavier.

With all 10g sliders, rpms started out in the upper 4k range and barely made it to 6 by the time I got to cruising speed...

The only noticeable drop to top speed I noticed was with the 10g rollers... every setup seemed to lose most of its grunt power around 55mph, only the creep from 55 to 65 seemed to change.

I couldn't care less about top speed, I don't try to ride on 55mph roads with other traffic doing 65mph. You are at the mercy of the 'cagers' not being able to accelerate away from traffic at those speeds. Plus, a steep grade on that 55mph highway puts me back to 45mph quick, so no thanks!

Here is a link to the sliders I got, this seller has 8g, 10g, and 12g for under $20 shipped.

http://www.ebay.com/itm/Variator-Wei...item5ae4829a86

I am impressed with the quality - I checked mine out after about 1,500 miles after reading a horror story about someone's cheap set melting/disintegrating in under 1k... but mine still looked new. Just a little dirty...
I also got a look at the cheap orange scrappy sliders I put in my 50cc I sold, they definitely showed obvious wear after a couple thousand. It sees WOT almost constantly, so maybe it builds up more heat...

[blueboy5000]

I just put a KOSO performance steep-ramp variator and 12g sliders on my MC-23 157qmj, and what a punch! This is on of the most dramatic performance upgrades I have done to a 157, if I had known it would be such a difference, I'd have done this to my other bikes a long time ago.

Compared to a stock variator with 14g rollers;

-way snappier acceleration

- hits hills 5 to 10mph harder depending on grade ( I still recommend NOT hitting hills hard)

- Increase in top speed to 65+ on flats (hauling my 210lbs)

-rpms still reasonable, redline at 7500.

[techie610]

Originally Posted by blueboy5000

I just put a KOSO performance steep-ramp variator and 12g sliders on my MC-23 157qmj, and what a punch! This is on of the most dramatic performance upgrades I have done to a 157, if I had known it would be such a difference, I'd have done this to my other bikes a long time ago.

Compared to a stock variator with 14g rollers;

-way snappier acceleration

- hits hills 5 to 10mph harder depending on grade ( I still recommend NOT hitting hills hard)

- Increase in top speed to 65+ on flats (hauling my 210lbs)

-rpms still reasonable, redline at 7500.

I have seen one, but never did it myself. Do you know what the drive face size is?

[blueboy5000]

Drive face is 115mm. Though I must point out there are many steep, long hills where I live. If you ride primarily on flats, then 13g sliders will do you fine.