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Post by benhonda on May 14, 2019 20:52:55 GMT -5
I turned a 50cc tao tao into a mini bike I installed a 1500rpm clutch spring kit and went to put in some lighter 16x13 rollers I had bought but found them to be taller than the ones that were in the bike...a big enough difference that it would have pushed the variator face out too far for the belt to go on without being pinched.
so I have 2 questions 1) does running higher rpm clutch springs with stock variator weights backfire? It seems like this should make the variator start to shift before the clutch engages, thus counteracting the higher rpms.
2) what size rollers might the bike need? When I looked online it seemed like the 50cc 139qmb takes the 16x13 rollers.
could the original rollers be worn down that much?
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Rune 75
Scoot Enthusiast
Posts: 441
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Post by Rune 75 on May 15, 2019 4:38:37 GMT -5
I turned a 50cc tao tao into a mini bike I installed a 1500rpm clutch spring kit and went to put in some lighter 16x13 rollers I had bought but found them to be taller than the ones that were in the bike...a big enough difference that it would have pushed the variator face out too far for the belt to go on without being pinched. so I have 2 questions 1) does running higher rpm clutch springs with stock variator weights backfire? It seems like this should make the variator start to shift before the clutch engages, thus counteracting the higher rpms. 2) what size rollers might the bike need? When I looked online it seemed like the 50cc 139qmb takes the 16x13 rollers.
could the original rollers be worn down that much? 1 yes exactly what you describe will happen. If you want the clutch to engage later (higher rpm) you also need a very stiff contra and some light rollers that will ceep the variator from starting to shift too early. This will also keep the rpm's high through acceleration and dont match the 139qmb powerband. A stiffer contra then stock is also a waste of power as it pinches the belt harder than necessary. 2 16x13 is the correct size. 3 Bike looks great. |
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Post by benhonda on May 15, 2019 22:59:14 GMT -5
the 1500rpm clutch spring included a stiffer contra spring
you say the higher rpm setup isn't good for the 50cc?
is there any benefit to just running lighter rollers?
I am trying to get the bike to have a little more pulling power. I know I can't expect much from a 50cc off road, especially since I weigh 250, but any gains over stock is better than nothing.
at what rpms does the 139qmb make peak power?
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Rune 75
Scoot Enthusiast
Posts: 441
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Post by Rune 75 on May 16, 2019 3:30:47 GMT -5
the 1500rpm clutch spring included a stiffer contra spring you say the higher rpm setup isn't good for the 50cc? is there any benefit to just running lighter rollers? I am trying to get the bike to have a little more pulling power. I know I can't expect much from a 50cc off road, especially since I weigh 250, but any gains over stock is better than nothing. at what rpms does the 139qmb make peak power? In my experience 4.5 - 5 gram rollers and stock contra spring gives the best results. Peak power is around 8000 rpm. I would also run stock clutch springs. The extra rews stiffer springs give on takeoff doesn't transform into faster takeoff. |
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Post by benhonda on May 16, 2019 20:58:59 GMT -5
Ok, i will put the stock springs back on and try just lighter rollers.
It is doing as you described, higher rpms but no noticeable increase in power or speed. Almost seemed to lose a bit of power when going up any sort of incline.
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Rune 75
Scoot Enthusiast
Posts: 441
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Post by Rune 75 on May 17, 2019 3:21:36 GMT -5
Ok, i will put the stock springs back on and try just lighter rollers. It is doing as you described, higher rpms but no noticeable increase in power or speed. Almost seemed to lose a bit of power when going up any sort of incline. Lighter rollers (4.5-5gram) and std springs will put the rpm's where your engine have peak power. It will give you faster acceleration and higher speed uphill. Top speed on flat roads wil probably not increase. |
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