Author Topic: Drive Belt Length = more speed?  (Read 805 times)

AylmerFreerider

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Drive Belt Length = more speed?
« on: September 01, 2019, 03:14:32 AM »
Just curious as I was checking part numbers when looking up drive belts for possible engine swap.

There were two different belts listed but one was a little longer.  737mm vs 743mm.

Would the longer belt give you more speed?
2015 Super 8 50R
72cc BBK
Polini Hi-Speed with stock boss and 6.5gr rollers
Naruko 1000RPM White Spring
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mousejunks

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Re: Drive Belt Length = more speed?
« Reply #1 on: September 01, 2019, 04:34:34 AM »
A longer belt adds an unknown variable. From my experience it causes more vibration at idle (being a looser fit) and slapping at higher speeds, colliding with the transmission cover.
'09 Kymco Espresso 150i
'11 Kymco Downtown 300i ABS - 79,500km
'17 Kymco Downtown 350i ABS

john grinsel

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Re: Drive Belt Length = more speed?
« Reply #2 on: September 01, 2019, 11:12:04 AM »
Probably not.   More speed equals bigger bike.

de dee

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Re: Drive Belt Length = more speed?
« Reply #3 on: September 01, 2019, 12:14:36 PM »
my 2011 downtown came with a belt size of 1010 / 24    30 degree, it reved high all the time, after I changed the belt with new one belt size  1004 / 24.5   30 degree,    the rpm dropped ,. over 1000 rpm.  more like other scooters every where,.  it seems the belt width has more to do with speed and power

AylmerFreerider

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Re: Drive Belt Length = more speed?
« Reply #4 on: September 03, 2019, 02:38:47 AM »
A longer belt adds an unknown variable. From my experience it causes more vibration at idle (being a looser fit) and slapping at higher speeds, colliding with the transmission cover.

The reason I ask is these two scooters have the same part number but the belt length is 6mm longer.  I read that it will get the the top of the variator to give you that little extra. 
Just curious because the longer belt is on the 2 stroke so more power obviously so I am wondering with the BBK if its enough power now to use that longer belt.  Also I have the Hi Speed Polini oversized variator so mike make a difference.
2015 Super 8 50R
72cc BBK
Polini Hi-Speed with stock boss and 6.5gr rollers
Naruko 1000RPM White Spring
Technigas Silent Pro Exhaust
3 x 1" Air Filter additions to Air Box

de dee

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Re: Drive Belt Length = more speed?
« Reply #5 on: September 03, 2019, 06:59:01 AM »
  have you tried looking at the variator with scoot on the center stand and rev. it up and watch how high the belt goes on the variator.,  would like to hear how it works.,  with the polini variator ,.  I have the malossi variator on my Piaggio b v 350 ., I had to put a malossi belt on to make a real DIFFERENCE,.  the belt is wider !

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