Low max rpm

[larryhobman]

I have been trying to get the rpm higher ever since I installed my new gears.  Before the gears I was at 9500 to 10000 Now my highest is 7200 and only 6000 in a headwind.  I have 6 gram sliders in right now.  Is there any way other than weight changes to change the rpm.  I have tried the blue racing cdi and it was worse than stock.  I put a new belt in and it is riding as high as you can get.  I have a 1000 koso contra spring in now should that be changed??  I can gain a lot more power if I can back to 8000 rpm.  Any idea's?

MY current set up:

2007 VIP 47mm BBK

A9 cam

#88 Main jet #34 pilot with pod filter
 Needle clip is at the lowest setting
6 gram koso sliders

1k koso contra spring

1500 clutch springs

timing mod

cleaned the ports up and port matched the spacer


49t/17t Gears


50.2 mph on my garmin gps @ 7200rpm
42mph @6000 into the wind

[90GTVert]

Why are you against changing the sliders out for lighter ones? That's the easiest way to get RPM up. A stiffer contra spring is the next common way. You could get a set of 4g sliders and if they were too light either stuff them with aluminum foil to make them up to about 1g heavier or mix them with the 6g (staggered) or both.

[larryhobman]

Hi 90GTVert,
Thank you for responding to my question. I was unsure that a stiffer contra spring would increase rpm, you say it will then I might get one. I am not opposed to lighter weights, I just did not want to spend the money and be disappointed again. If my weights are too light then I will definetly need a heavier contra spring too, is that right? Weights and springs are the only 2 ways to increase the rpm??? What would you suggest I do first?

1. 4 gram sliders or the 1500k contra spring

2. both the the spring and sliders

[larryhobman]

Hi 900GTVert,
If you are ever going down rt9 to LEWES or REHOBOTH BEACH I would to have you stop by to test my scoot and give your thoughts.

[90GTVert]

Jun 1, 2016 12:09:55 GMT -5 larryhobman said:

I was unsure that a stiffer contra spring would increase rpm, you say it will then I might get one. I am not opposed to lighter weights, I just did not want to spend the money and be disappointed again. If my weights are too light then I will definetly need a heavier contra spring too, is that right? Weights and springs are the only 2 ways to increase the rpm??? What would you suggest I do first?

1. 4 gram sliders or the 1500k contra spring

2. both the the spring and sliders

The rollers and contra spring work against each other to control pulley opening and closing. A stiff contra spring will try to keep the rear pulley closed and prevent shifting more than a soft spring with the same rollers. Lighter rollers provide less force to counteract the contra spring and try to open the rear pulley. You have to have the right balance of the two and you need to use a contra spring stiff enough to keep tension on the belt.

If your weights are too light, a stiff contra spring will only make it worse.

Lighter rollers or a stiffer contra spring = More RPM
Heavier rollers or a softer contra spring = Less RPM

Those are the main ways to change RPM. As long as the contra is stiff enough to keep tension on the belt, I usually just swap rollers around.

[larryhobman]

Thank you Brent.