A hardworking SA50 needs some speed but must maintain torque

[mwilliamshs]

Stock runs about 37 mph.
Adding 9:1 gears, a Polini Variator, and a 90/90 get 49 according to Wheelman's experience. (math says 57, insufficient power to realize potential)
Adding just the Polini Variator and a 90/90 get 42 according to Wheelman's experience. (math says 42)
Adding just the 9.8:1 gears and a 90/90 get 44. (math says 44)

With that info we can determine what the Polini is actually doing and what it's worth in RPM and MPH.

Stock = 7,574.97 RPM at 35 mph and 12,985.67 revs per mile @ highest ratio possible from the CVT (.85)
and 35.25 mph @ 7,631.22 rpm with a 90/90

9.8:1 = 5,981.63 RPM at 35 mph and 10,254.23 revs per mile with a 90/90
and 44.65 mph @ 7,631.22 rpm with a 90/90

9.0:1 = 5,493.33 RPM at 35 mph and 9,417.15 revs per mile with a 90/90
and 48.62 mph @ 7,631.22 rpm with a 90/90

So if a Polini and a 90/90 gets us 42 mph at ~7,631.22 we can calculate what gearing benefits it offers.

42 mph = 2,661,120 inches per hour/ 51.45 inches per tire revolution = 51,722.45 tire rovolutions per hour
51,722.45 tire rev per hour/ 60 = 862.04 tire rpm x 12.12 final reduction = 10,447.934 engine rpm
10,447.934 rpm x .85 stock overdrive = 8,880.7445 engine rpm in stock form

7,631.22 stock except 90/90 peak / 8,880.7445 @ 42 mph = .859 additional overdrive of Polini

So a Polini Variator based on Wheelman's results provides an additional ~14.1% overdrive over stock. Direct is 1:1, stock gets to about .85:1 and the Polini gets to about .723:1.

So a Polini with its .723:1 and 9.8:1 and a 90/90 should be good for 8,722.12 revs per mile and 52.49 mph @ 7,631.22 (same RPM as 35 mph stock except 90/90)

[Rip_City_Spree]

You might need rollers for tuning purposes. By changing rollers weights you can either get more low end with lighter weights or more top end with heavier weights generally speaking. A good variator is a sound investment. There is lots of info on the interwebs about cvt tuning.

[mwilliamshs]

So after doing all the math and reading, reading, and reading...
like reading this:

Greetings:

I already had a Polini variator, transplanted from Flash II along with the externally-adjustable Polini 2-shoe clutch, both of which have performed very well. They ought to for that money. Stock belt for now. If you axt me I'd say the Keli + OKO ramp plate was almost as good for half the cost.

Limp sold me the 9:1 Ruima gears for a fair price and well, they're gears. I don't expect any trouble. Finishing off the drive train is a Pirelli SL26 90/90x10 tubeless rear tire on a tubeless Met rim.

I deliberately stuck with the stock carb and intake for now, jetted to the UNI pod. As long as jetting is optimal, and engine pulling through a smaller carb will make less power & heat than one with a full-sized mixer. Arguably the smaller carb will be better in the low-midrange too. I want a trouble-free reliable scooter, not absolute max output bragging rights. So far it's working, but I have yet to see what temps I get when I pull out the whip. I get uncomforable when I read >350 on my CHT. Right now I see 325 with the 101 and I'll go up if necesary. After break-in I plan to try my oddball Keihin VE24 CV carb, familiar to CH150 Elite owners. With the CT Chrome manifold adapted, it worked pretty well on Flash II.

Outcomes:

Bone stock [with Polini Variator] with big tire: GPS =42.7 (~45 Indicated)
Added Ruima 9:1 only: GPS = 47.8 (~50 Indicated)
Added Nikasil+V8 Pipe: GPS anticipated = 55, who knows? Bye-bye speedo-needle?
(by my rough calculations, 8500 RPM should produce 58.7 MPH. Tire expansion offsetting belt slip/traction)

Flash II's best-ever: 58.7 GPS, although it went faster on at least two other occasions when I was without GPS.

I think if you want to do ~45ish you can either:

run 9.8:1 gears and a 90/90 = 44 mph and ~$50 (may need roller/spring mods to regain takeoff)
run 9.0:1 gears and a 90/90 = 48 mph and ~$50 (may not be any faster than 9.8 due to limited power)
run a Polini vari and a 90/90 = 42 mph and ~$100 (may require spring/roller mods post-install)

Or combine some of the above

run 9.8:1 gears, Polini vari, and a 90/90 = 52 mph. Likely power limited IMO...why?

Adding 9:1 gears, a Polini Variator, and a 90/90 gets 49 according to Wheelman's experience but the math says it should do 57mph.

9:1 gears x .723 (Polini calculated O/D) = 6.507 x 1231 (90/90 rev/mile) = 8,010.117 (engine rev/mile)
that's 4,672 RPM @ 35 mph (well below peak power. if your CVT isn't tuned well you could get things pretty toasty at slower speeds/higher loads) and 57 mph @ 7,631.22 (original peak).

This gearing and a stockish motor has insufficient power to realize its potential speed. 9:1 gears will be even less capable in this regard than 9.8:1 gears.

9.8-9.0=0.8 and 0.8/9 = 8.8% less power from 9 than 9.8, or 9.0 gears are only putting down 91.8% as much power as 9.8s. If 9.0s lose 14% of their potential (49/57) and 9.8s are ~9% more powerful than that (9/9.8 ) then they should lose only about 12% of their power (.91x14). 12% of 52mph is 6.24, so just as Wheelman has demonstrated gears/vari that should run 57 actually get you only 49, gearing that's theoretically capable of 52 may actually pull only 45.76 mph. There's a sweet spot in there where you won't lose much at all and it might be in the 9.8 neighborhood but even if it's not, I'd expect a '9.8, polini vari, 90/90' combo to pull 45 pretty readily since it should knockout 44 mph on gears alone...but when you look at it that way it seems like that Polini might really only give up ~2mph for the $90 spent...not good IMO.


For the total money invested I think I'd go 9.8.
For the time/labor demand I think I'd go Polini.
For the ultimate working budget scooter with raised top speed I think I'd go Polini and 9.8s.

What would you do?

In reality I think I'll order the SEF plate ($18 @ scooterswapshop), a roller kit of mixed weights for tuning ($25 @ scooterswapshop), a spring set of mixed tensions ($23 @ scooterswapshop), and a set of 9.8s ($49 @ scooterswapshop) and add a new belt ($26.50 @ scooterswapshop). $141.50 total. This is more work to install than a variator but it'll be done once and for all and if/when I want more pep I can add a polini variator ($90 @ scooterswapshop) easily and move toward 52 mph top speed. Might shop about for a used Ruckus variator after I research the griding required.

Sidenote: ScooterSwapShop has a Dio Power Kit Stage 1 for $256 that includes the Polini Variator ($90), Polini Belt ($26.50), set of gears ($49), spring kit ($23), and a Malossi Plug-and-Play CDI ($92). Individual prices total $280.50 so ordering the kit saves $24.50. I don't think I'd benefit from the Malossi CDI since US bikes don't have a revlimiter and the kit "savings" would basically pay for the roller kit I might need anyway. Buying the parts I mention "in reality" plus the variator I might add later total only $231.50, still cheaper than the "kit".

Anybody with thoughts on the Malossi CDI? *Note* this is not the immobilizer CDI.

[mwilliamshs]

Variator, and deres trick should get you to 45...

What's "deres trick"?...

...But your access will suffer...

My what?...

Think I figured it out. "deres trick" = de-restrict and "access" = acceleration.

[mwilliamshs]

The Diameter matters. Stock Aero/Dio is 87-ishmm. Polini for Aero and SA is 90. Ruck is around 91 or so, methinks. Polini-for-Ruck is 94. I took a chance and bought an unknown for-Ruck item that measures a whopping 97 and managed to make it fit. It's the one I'm using now, but not convinced it's better than the Polini on top. However I like its midrange performance.

Even with a 94, a longer belt may be needed or it will bottom out a stock belt in the rear pulley and potentially overheat and break.

The other issue is the fixed side of the front pulley. The conical diameter is 93mm on the Elite. It may be a tad larger in my Kymco sheave, but probably not 97.

If you keep the stock rear pulleys, Polini 248.006 belt and careful atention to shimming the front boss works well in the SE05 case with an oversize variator. Malossi also once had a longer 15.5mm wide belt. You have to make sure the belt rides as close to center in front without slipping.

...As for the shaving for the polini for ruckus. It's is a quick an easy job with a dremel.

Different angle, but I think I get the idea:

52.6 stroker bottom end with big black ct manifold

[1man8scoots]

Gotta love someone using my images yet in another post you're mocking me. Good luck with that.

[mwilliamshs]

Gotta love someone using my images yet in another post you're mocking me. Good luck with that.

You meant image, right?

Oh, then you deleted it from both threads. You mad, bro?

[1man8scoots]

I'm sure you don't want me to correct your mistakes. Tj has already done the research.
Cheers.

[maddog]

Real easy guys, the "sr" is the derestricted version of the "s" sr= 45mph and with 9 to 1 gears= 53mph.