Back to the reality of the Chinese four-stroke scooter in front of me; I got some parts in to see if there's much left in it from CVT components. A DrPulley variator, 842-20-30 Gates Powerlink drive belt, and then a couple of things that Enviromoto had on clearance. 14g sliders, just in case the DrPulley liked something heavier and an NCY torque driver that was only $25.
Before I did anything else, I put the woodruff key back in place since the additional advance didn't do much more than heat the engine up.
Then I marked the variator and took a ride with the setup that I have been using : stock vari, 10.5g sliders, 1K contra, stock clutch springs, Bando 835-20-30 belt. With no tucking, just regular riding like all other setups tried here, it maxed at 57.3MPH (tailwind) @ 8350RPM and left 3.3mm of marker on the variator.
Then I tried out the 842-20-30 Gates Powerlink belt. Many people online seem to swear by this thing. It's way taller than the Bando, which makes it unable to sit near the drive boss and seems to affect it in all positions. The pics below show the Bando vs the Gates in their idle positions.
I changed nothing but the belt and went for another ride. It was obvious on the first rev before I left that the lack of "1st gear" position (not sitting deep in the front pulley or high in the rear pulley) made the stock clutch much more mild. I've been perfectly happy with the stock clutch springs, but having the clutch spinning fast at idle makes it engage pretty much when the throttle is touched. Once I got moving, RPM was low and acceleration was sluggish because of it. I saw a max of 53.0MPH @ 6950RPM. It wasn't making enough power to keep pulling, even with a tailwind like the 1st ride (same route). I had a 4mm mark left on the variator.
Maybe there's potential for the Gates, but I don't have sliders light enough to make use of it. I can go 0.5g lighter, and that won't get RPM up to where I need it.
Then I switched to the DrPulley variator kit to see how it would do. Below are pics of the kit and the DrPulley vs stock. The DrPulley variator is 114.7mm vs 107.7mm stock. The fixed halves are nearly identical in diameter, with the DrPulley at 114.7mm and stock at 114.8mm. The drive boss for the DrP is 51mm and the stock boss is 51.6mm but the DrP fixed half has a raised center section of roughly 0.5mm that is the same size as the boss diameter and acts like a longer boss. Notice the longer ramps in the DrPulley and the quality bronze bushing vs steel junk bushing in the stock variator.
The splined fixed half of the DrPulley went onto the crank very snug. I used a socket to tighten it on by hand at first, because I was worried about hitting it with an impact and tearing something up. It went on OK though. No issues. Once installed, I could see why most variators for the GY6 stop around 115mm. Much more and you'd have to remove the kickstart parts, and it's not far from the cases either.
The first run was with the Gates belt and the same other parts as the previous tries. The Gates belt sat equally as poorly in the DrP vari as it did in the stock piece. RPM picked up on launch, but remained very low. I saw a max of 52.0MPH @ 6800RPM. It seemed like the variator helped launch, but dropped RPM even more and hurt speed. Again, I just don't have sliders light enough to use the Gates belt, and I probably won't spent the $20 to get any right away. I had 3.4mm of travel left on the variator, but keep in mind that the DrP variator is larger, so it indeed did see more travel than stock.
For my last test run, I used the same setup with the Bando 835-20-30 belt instead. It sat about the same in the pulleys with the DrP as stock at idle. Once again, it was much better than the result with the Gates belt. RPM shot up over 8000 on takeoff and then settled down in the mid 7000 rev range for higher speeds, making it's way up to about 7900RPM at 55.6MPH max (again a tailwind like every other max speed here). It only left a 1.5mm mark on the larger variator, so I must question the need for the Gates (if it's truly longer anyway) on the stock variator especially.
I put a clip from each of the above 4 runs into 1 vid below so you could see/hear the changes made for yourself.
It worked pretty well with the DrPulley variator and the Bando belt, but I thought if I could get RPM a little closer on launch and at speed, it would be as good as I could expect and quite steady. I hoped the NCY torque drive with it's choice of a steeper straight groove or a dual angle groove may do the trick. Unfortunately, my torque driver cover is too small to fit over it, so that testing ended before it began.
I may have seen some improvement in speed if I switched to 10g sliders vs 10.5g and got RPM up at speed, but I decided to just take a regular ride before any more changes were made. That didn't go so well. It died out on me totally twice and ran very poorly on a few occasions. I saw a max CHT of 522F! At the time I was thinking maybe I managed to soft seize it and I was gonna kill the engine. Part of me was so fed up with the lackluster GY6 that I didn't really care.
From the sound and actions, I was thinking it was running lean from either the winds (they got really strong for a bit and the TaoTao leans out with wind gusts to 16:1 at times and loses power) or a fuel delivery issue. It never ran poorly when very hot, and power came back to normal. It ran as hard as ever the last 5 miles to home. I was glad to see such a simple issue of a loose intake/carb screw letting air past when I took a look.
I doused it with threadlocker and tightened the clamp and then took another ride, stopping at a gas station first. I filled up and calculated 61MPG. Even with the previous issues, I decided to use 87 octane vs the 93 I've been using. I assumed that since I never detected knock with the timing advanced 6-8 degrees using 93 octane, it was likely to work fine.
I went about 5-6 miles from the gas station WOT all the way other than a brief 30MPH section and then came back doing the same. No problems. It still got hot... 470s, but better than before. I'm still thinking I should probably upjet just a tad, maybe 112 to 115 first, and see if that does anything in real riding conditions. I'll still need to use other cooling solutions I'd imagine, because I think it's gonna be hot anywhere it's relatively in tune.
Walked back inside with "I Like Chinese" by Monty Python playing in my head.
