Help with roller weights

linkkokiri83 · 08-13-2016, 04:01 PM

100cc, current weights unknown. Scooter seems to go into high very early, lacks push to get up to top speed. I am looking for more zippy acceleration to get up to 35 mph quickly. Im sure iys the weights, but possibly a bigger jet is needed in carb. Any advice on what to get?

wheelbender6 · 08-13-2016, 08:03 PM

You may just have to pull out your rollers to determine what weight they are.

blueboy5000 · 08-24-2016, 08:38 AM

Since it " goes into high" quickly, that's pretty much what it's supposed to do.

"lacks push" is more of a misunderstanding of the engine's operation on your part, than a rectifiable situation.

Top speed of a gy6 with an 83cc BBK is only about 45mph flats, 30mph on moderate hills.

Shadowfire · 09-04-2016, 02:49 AM

The knob that you are looking to turn here is the roller weights.
I can't stress this enough - DO NOT mess with the carburetor or jets.
Changing the weights adjusts the RPM that the clutch kicks in at and the bike starts to move.

If you make them lighter, the clutch engagement RPM gets higher, and you get better acceleration (because the engine is burning more gas and firing more often). ALSO, your fuel economy will suffer. Mileage = (distance traveled per turn of the engine) divided by (fuel used per turn of the engine). When cruising around at 20mph, the bike might typically (at stock) engage the clutch at 2000rpm and run up to 4000rpm. If you set your weights to engage at 5000rpm, your engine will still be running at ~5500rpm @ 20mph with the new weights. Your engine is burning the same amount of fuel to move the bike forward, PLUS more fuel to overcome additional engine friction losses and intake/exhaust restriction directly due to the higher rotational speed.

If you make them a bit too light, you will lose some top speed.
If you make them far too light, you will lose a LOT of top speed, or possibly fail to engage the clutch.

Its not too difficult to change the weights or to go back to stock, so go ahead and play around with it. You'll have to determine for yourself if the loss of top speed is worth the increased acceleration.
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Top speed is determined primarily by engine horsepower, transmission drive ratio/tire size/engine speed limiter, and wind resistance (aka bike shape). That's why when you mod the hell out of an engine (like blueboy5000's) you primarily get better acceleration, and not a lot more top speed. I have a 49cc 2stroke which will move my fat 260# ass to a top speed of 50mph on flats (takes a while to get there). I can barrel DOWN a fairly steep hill (8 degree incline) and hit 54mph, but it simply will not go faster; it has enough engine power that you would think it should do a bit more, but there are other factors (primarily the tranny drive ratio) which stop it from doing so. That bike as a stock but unrestricted unit tops out at ~42mph on flats.

08-13-2016, 08:03 PM	#2
wheelbender6 Join Date: Mar 2010 Location: Houston area Posts: 945	You may just have to pull out your rollers to determine what weight they are. __________________ "Beer never broke my heart" - Luke Combs
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09-04-2016, 02:49 AM	#4
Shadowfire Join Date: Feb 2015 Posts: 121	The knob that you are looking to turn here is the roller weights. I can't stress this enough - DO NOT mess with the carburetor or jets. Changing the weights adjusts the RPM that the clutch kicks in at and the bike starts to move. If you make them lighter, the clutch engagement RPM gets higher, and you get better acceleration (because the engine is burning more gas and firing more often). ALSO, your fuel economy will suffer. Mileage = (distance traveled per turn of the engine) divided by (fuel used per turn of the engine). When cruising around at 20mph, the bike might typically (at stock) engage the clutch at 2000rpm and run up to 4000rpm. If you set your weights to engage at 5000rpm, your engine will still be running at ~5500rpm @ 20mph with the new weights. Your engine is burning the same amount of fuel to move the bike forward, PLUS more fuel to overcome additional engine friction losses and intake/exhaust restriction directly due to the higher rotational speed. If you make them a bit too light, you will lose some top speed. If you make them far too light, you will lose a LOT of top speed, or possibly fail to engage the clutch. Its not too difficult to change the weights or to go back to stock, so go ahead and play around with it. You'll have to determine for yourself if the loss of top speed is worth the increased acceleration. ------------------------------------------------ Top speed is determined primarily by engine horsepower, transmission drive ratio/tire size/engine speed limiter, and wind resistance (aka bike shape). That's why when you mod the hell out of an engine (like blueboy5000's) you primarily get better acceleration, and not a lot more top speed. I have a 49cc 2stroke which will move my fat 260# ass to a top speed of 50mph on flats (takes a while to get there). I can barrel DOWN a fairly steep hill (8 degree incline) and hit 54mph, but it simply will not go faster; it has enough engine power that you would think it should do a bit more, but there are other factors (primarily the tranny drive ratio) which stop it from doing so. That bike as a stock but unrestricted unit tops out at ~42mph on flats.
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