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Scooters - 125 to 300 => Yager GT 200i => Topic started by: Yager200i on July 01, 2014, 02:02:48 AM
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The OEM rear gear set has an 8.48:1 ratio. I want to try dropping engine RPM down to the torque peak at 6500 RPM at 65 MPH, so I calculate that I need about a 7.82:1 rear gear set.
Anyone know where to buy such a thing?
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I doubt there is any other gearset's for our scoot as it probably grew out
of a smaller engine. I have changed my cruising RPM's though by changing
the roller weight and filing a few things in the CVT...
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Which things did you file? I'm assuming you took a bit off the variator sheave faces, and shortened the boss a millimeter or so? I can do that easily enough... will the belt still have clearance with the surrounding case at high gear, though?
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Ok, just to provide closure on this thread... I had new rear gears cut.
The original gear set was 8.408:1 (the manual says 8.48:1, but the teeth count and gear diameters prove it's actually 8.408:1), the new gears are 7.15:1. This should get the engine into its torque peak RPM range at 65 MPH, which should help to increase fuel efficiency a bit.
The top end of the bike should be ~94 MPH, if the engine's got the gumption to get up to that speed. It probably won't until I get the new aerodynamic nearly-fully-enclosed fairing completed, but it'll be nice to cruise without the engine windmilling its heart out.
The low-end speed won't be much changed... at the clutch engagement speed of 4000 RPM (engine), it goes from ~10 MPH stock to ~12 MPH with the new rear gears. I'm still looking for a clutch that has more clutch face to it, and I'll set it to engage at 2800 RPM (engine). That'll give me a low-end speed of ~8.5 MPH, so I'll have a wider speed range bottom and top, which will make it easier to control the bike when threading the needle through heavy stopped traffic.
Original gears:
Gear 1: 15 teeth
Gear 2a: 43 teeth
Gear 2b: 15 teeth
Gear 3: 44 teeth
New gears:
Gear 1: 16 teeth
Gear 2a: 39 teeth
Gear 2b: 15 teeth
Gear 3: 44 teeth
The guy who cut the new rear gears for me is Jan Vos from Belgium. The total cost was $206.79 US.
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Moto randy how did you file the variator ramps, I found a elec. 1/2 " file by black & decker, first one I did took me all week end, after with the file it took me 1/2 hour,. then I polished it with 400 grit belt, waiting for the snow to go away, so I can try out the new variator, the first one done by hand kind of rough, this one looks like factory done,. going to try it two ways with Dr. pulley sliders 20/12 14 gram. and modded Dr. pulley 21/12 14 gram sliders,.
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Yager, do you work for NASA? I've never seen anyone go as crazy as you on a scooter haha. Props man, keeping it real.
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Please keep us informed.
I have a set in my ZX that were custom cut for Moped Hospital, and they worked great for top speed runs but had to come back out for street use. 6.1:1 was the final ratio.
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I'm putting in 1000 RPM clutch springs, so that should give me better low-speed controllability, especially when trying to thread the needle in stopped traffic.
I also extended the torque cam grooves a tiny bit on the driven pulley with a Dremel tool, so that should give me a tiny bit wider gear range from the variator. I estimate I'll have a low-end clutch engagement speed of 2700 engine RPM and 8.25 MPH, and a top-end of 9200 RPM and ~94 MPH.
Fortunately, the new Avon Stryker tires are rated to 94 MPH, so if the engine's got the oomph to get up to that speed, the tires can handle it. I'm going to wash down the tires with dish soap (to remove the mold release oil) and wire brush them (to scrub off the outer slick layer of rubber) in lieu of scrubbing them in via riding... that way they're pretty much good to go from the start.
I got the new rear tire on today, along with the MOTO-D Angled Motorcycle Valve Stem (11.3mm), the tire went on pretty easily using three tire irons, the valve stem fit perfectly.
Right now the bike's torn down... variator's off, clutch is off, rear wheel is off. Tuesday I'll be taking the rear gearbox cover off and putting in new bearings and the new rear gears.
Anyone know how to flush the OEM grease out of new bearings and put better grease in it, without destroying the dust cover on the bearing? I've got some Royal Purple grease I want to put in them.
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Use an exacto knife. You can go into the seal at a few points till you find the sweet spot.
They are made of something like a soft steel / tin alloy so they will deform way before they crack or chip off. You can VERY easily remove them, and straighten out any anomalies. Plus the rubber coating will seal again like you were never in there.
I'd also use acetone to remove the OEM grease. It will leave no residue unlike other de-greasers.
It's way easier than you think, and the result will be perfect.
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Well, I decided to go a different route... I'll be buying hybrid ceramic bearings for all 10 of the roller bearings on the bike. There's a company called MicroBlue that sells bearings they've micro-polished the bearing race on, then put in silicon nitride balls, then coated the whole thing with tungsten sulfide so they roll a lot easier than even hybrid ceramics usually do.
The only two bearings I can't replace with hybrid ceramic are the two drawn cup needle bearings... one in the clutch, one in the rear gearset... but since the OEM needle bearings are the typical Chinese cheapies with a nylon roller cage, I found my needle bearing on the clutch is already worn out... which is why the clutch has started to chatter when engaging.
So I'm trying to find better-quality replacements for those. I'll have MicroBlue do their micro-polish and tungsten sulfide coating on them as well, so they spin easier and last longer.
I'm having the same micro-polish and coating done to the new rear gears, which will do away with gear break-in and give less friction.
After I get the new head on and the new rings broken in, I'll put tungsten sulfide in the oil to slicken things up inside the engine.
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I never heard of this "tungsten sulfide. Sounds interesting.
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It has the lowest coefficient of friction of any lubricant additive out there. It's also called WS2.
Check out MicroBlue's two sites:
http://microblueracing.com/ (http://microblueracing.com/)
http://www.microbluebearings.com/ (http://www.microbluebearings.com/)
I especially like the hole shot video they show of a motorcycle race... the guy jumps to the front, his neck craning back from the acceleration. Heh. Almost comical how quickly that bike took off.
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LOL!!! That kid wasn't expecting that!