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Post by usmcdoc on Jan 28, 2012 21:01:29 GMT -5
Oddball thought....both my 1E40QMB engines use 15X12 variators. Many wish to get more top speed...and note that their belt does not run all they way up the CVT....giving a higher ratio. I commonly see 17X12 rollers in 2 stroke weights that would give an additional closing on the variator possibly?Due to being 2mm larger in diameter.Anyone try or ever think of this?.. :2cents:
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Post by Fox on Jan 28, 2012 21:09:26 GMT -5
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Post by Fox on Jan 28, 2012 21:15:43 GMT -5
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Post by usmcdoc on Jan 28, 2012 21:18:14 GMT -5
Just measured a set of my GY6 rollers....16X13......they are 16mm diameter and 13mm wide.....then a set of Minarelli weights 15X12....they are 15mm diameter 12.1mm wide....so maybe the 17X12 mm would work in a Minarelli?... :scoot:
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Post by lauriejennifer on Jan 28, 2012 21:36:21 GMT -5
I'm new to this scoot thing, obviously. Are you guys talking about the equivalent of changing sprockets on a chain-driven? It sure sounds like it. But, you know, ass-u-me...
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Post by Deleted on Jan 28, 2012 21:38:04 GMT -5
I'm new to this scoot thing, obviously. Are you guys talking about the equivalent of changing sprockets on a chain-driven? It sure sounds like it. But, you know, ass-u-me... Yep  |
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Post by lauriejennifer on Jan 28, 2012 21:39:27 GMT -5
I <3 learning!
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Post by Fox on Jan 28, 2012 21:48:06 GMT -5
Not exactly. The belt on a scooter is like the chain on a 18 speed bicycle. It travels up and down the pulleys to alter the ratio of engine RPM's to rear wheel RPM's just like the chain on a multi-geared bicycle only it happens smoothly. The weights act against a spring inside the rear pulley using centripetal force when you gas it and the spring acts against the weights when you let off the throttle to return the belt to idle position.
Your bike's chain and sprockets never change geometrically. The transmission in your engine makes the little front sprocket spin at a set rate for each time the engine rotates around one time in first gear. Second gear spins it faster etc...In other words you change gears on your bike to alter the number of times the front sprocket spins per each engine revolution.
You can alter the size of your sprockets to achieve more torque or more top-end speed just like a bicycle. Smaller front sprocket=slower but more torque. Larger front sprocket=faster Larger rear sprocket=slower but more torque for hill climbing. Smaller rear sprocket=faster. Usually you have to make the chain a little bit longer or shorter when you change sprockets.
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Post by lauriejennifer on Jan 28, 2012 21:58:25 GMT -5
Gotcha. It still sounds like you're talking about changing ratio, though. The difference is you're basically doing it inside the transmission (sort of...), whereas on my motorcycle I'm changing it at the final drive gear (aka, front sprocket--since it's the easiest and quickest).
But, we're both talking about changing the ratio. ...I think?
I initially went down 1 tooth on my front sprocket, but then when I did the big bore, this made my bike an unrideable wheelie monster in 1st. 1st was useless on the street (would be great in the woods!). Then, I went up 2 teeth for a track day (had to remove the case saver to fit it LOL). This was great for a WOT track, but boring as heck on the street.
I've come full circle and now run stock gearing on my bike again. LOL
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Post by jmkjr72 on Jan 28, 2012 22:04:26 GMT -5
well to change ratio we tear into the final drive and change gears in there
unless you change the size of the varatior you realy dont change your ratio
the problem is that many stock set ups you actualy cant get all the way to the final ratio without fine tuneing
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Post by lauriejennifer on Jan 28, 2012 22:08:32 GMT -5
Ah. Man, I'm such a newb.
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Post by jmkjr72 on Jan 28, 2012 22:15:02 GMT -5
there just not as simple as they look
kinda think of it this way the cvt is an autotrans in a car cant realy change the ratios(well with the cvt we can change ratio by installing larger varatior and rear sheave or by using diffrent belts)
and the final drive is just like a rear end in a car
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Post by Fox on Jan 28, 2012 22:43:22 GMT -5
You are correct on the "ratio" thing. By altering the amount of belt travel on the pulley faces you can increase the ratio and make the scooter faster. The only way to do that is to alter the stock pulleys or buy an aftermarket variator that has different geometry than a stock one but they ain't cheap. You can alter the way it acts by installing a stiffer spring in the rear pulley and by increasing or decreasing the actual weight of the roller weights. They come in 4 gram, 4.5 gram etc... For most people just altering the weights alone is enough to make your scooter perform to your liking. The 50cc scooters are usually setup for a slower take-off than they are capable of so by decreasing the weight of the rollers you essentially make the spring in the rear a little stiffer which delays the action on the variator which in turn allows the engine to rev higher on take off and stay in the lower ratio longer so the higher revs give you a better hole shot. You go too light and the spring over acts and you lose top end speed but you can walk up any hill. That's what they call "CVT tuning" Continuously Variable Transmission.
Guys like Brent and Robert are never satisfied and look for ways to get 1/2 a mile an hour more so they actually alter the metal parts by hand.
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Post by 90GTVert on Jan 29, 2012 10:48:25 GMT -5
On the initial topic, even if it the 17mm rollers gave you a boost in top-end, they might take some take-off power. Not sure, but they may keep the vari open a little at all times and you wouldn't be able to get the belt into the best "first gear" position. I could see them possibly helping top speed if you couldn't get full travel on the variator faces... maybe. Don't think it'd be worth it though. A sluggish start makes scoots a lot less fun IMO, but then I need a lot more help since I'm heavy.
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Post by lauriejennifer on Jan 30, 2012 11:36:48 GMT -5
Torque over top end any day, in my opinion! Why do you think I switched from a sportbike to a supermoto? Sure, my top speed now is only 80mph (with 351cc), but getting there is just soooo much fun! *brraaaaap!*
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