2020 bmw c650gt rollers placement
- Thread starter Lps3000
- Start date
Lps3000
New member
I was thinking about that
What is the weight of the OEM rollers?
Are the 30 gr dr.pulleys good ??
I weighed the set in my 2013 GT, 33 gr, the 30 gr Dr Pulley will help off the line acceleration without much loss of top speed, the biggest benefit of the Dr Pulley is the shape. The wedge shape and sliding allows the variator to get "smaller" (ramp of the wedge allows the two sides of the "pulley" to get closer making the pulley act smaller) then as the RPM increases the wedge travels higher, making the "pulley" larger to move more surface of the belt, moving the driven wheel faster. Heavier weights move to the outside easier (higher speed) while lighter weights move in easier (quicker acceleration) but their lighter weight hinders their movement out (loss of top speed).I was thinking about that
What is the weight of the OEM rollers?
Are the 30 gr dr.pulleys good ??
Please take this with a grain of salt, this is MY reasoning from my research, studying the whole set up as I replaced my belt and installed the 32 gr Dr Pulley and many years of working with electric motors and different pulley combinations. The 32 gr Dr Pulley I installed improved my acceleration from stop, greatly improved my mid range, didn't affect my top speed or fuel economy and smoothed the bike during accelerating or slowing. Most of my riding during this time was back and forth to work with about 25 miles of Interstate and I was setting the bike to ride to Nevada (from Georgia) when I retired. The company I worked for laid me off because I wouldn't retire, then elbow surgery, cancer, and rotator cuff surgery has me putting that ride off till this year. My set-up is good for my use, if all my riding were stop and go, short trips and limited highway I would have used lighter weights for better acceleration, but the mid range and cruising speeds were a higher priority at the time. Good news is, cancer seems to be gone, this week I've gotten back on the scooter for the first time in 5 months and I'm still loving it.. Happy New Year!
Delray
Well-known member
This describes 95% of my riding. I installed 28 gram Dr. Pulley sliders (and you need the four insert pieces) and was very pleased with acceleration and mid-range.
RollaCosta
Active member
Did the lighter rollers increased rpm at same speed?
Delray
Well-known member
Honestly couldn't tell you. I find the BMW tach system lacking, if not annoying. The horizontal bars in steps of 1,000 rpm's is imprecise and hard to read at speed. My general sense is the new sliders didn't have much effect on rpm's.
RollaCosta
Active member
Given such drastic difference in roller weights between your 2013 and my 2017 models - 30g vs 43g, I suspect that BMW simply copied Dr.Pulleys variator design which also uses 43g rollers. To tell the truth, I was quite happy with mine and will probably go back to it - only with Dr.Pulleys sliding rollers of same weight just to see how much shape affects things.
It is also of note that my J.Costa was designed to use the same total displacement weight, namely 16x21.5g vs stock CVT of 8x43g.
I knew that would be too high rpms and bought 25g but still a bit over my liking. Maybe 25.5 or 26g would be perfect but impossible - even with maxed out 25g rollers the metal is sticking out the back of those J.Costa fingers!
It is also of note that my J.Costa was designed to use the same total displacement weight, namely 16x21.5g vs stock CVT of 8x43g.
I knew that would be too high rpms and bought 25g but still a bit over my liking. Maybe 25.5 or 26g would be perfect but impossible - even with maxed out 25g rollers the metal is sticking out the back of those J.Costa fingers!