Rollers, what a difference By daver (Read 1,109 times)

[daver]

Hello all..
Just back from a nice ride.. Wow, what a difference new rollers make..
I have been fighting what I thought was a grabby clutch since my YY250T was new, and everything I did to it was only a temporary fix..
Well, I took out the factory rollers (3x26g and 3x24g) and replaced them with this set in 22g www.partsforscooters.com/169-150_250cc_Roller_Weights?sc=2&category=124390 ..
Now with the lighter rollers my engine can come up to a decent rpm before the clutch engages, seems it was just lugging the engine down before because it was locking up in the low 2000 rpm range..
This bike has never really ran over about 4000 rpm except down hill, I am now able to get in the 5000 rpm range just taking off from a stop..
Well, all the grief I dealt with and it was simply to high of gearing..
To anyone having similar issues I would recommend you remove and open your variator, and weigh those rollers, you might just need to put in a lighter set..
This really is a cheap and easy fix..
I am sure the factory rollers might of been great for a 120 lb rider, but not for me..
Good luck and happy scooting all.. Dave

[scootaway]

Hi Daver I don't think changing the weight of the rollers make the clutch engage any quicker or slower. Whatever weights you use, on idle the variator is going to spin, so is the belt and so is the clutch unit. Changing the springs inside the clutch unit could engage it sooner.

[daver]

Scootaway,
Logic tells me your right.. I am at a loss to explain it, but my engine sure likes the lighter rollers better.. I do know that I am running quite a bit more rpm's by the time the clutch locks up though.. Whatever the reason, I'm a happy camper.. Dave

[Cruiser]

Hi Dave,

My YY250T had 24 gram rollers stock from the factory. I switched to 19 gram sliders. Acceleration was greatly improved with no loss of top end. 5000 rpm yields about at an actual 55 mph. The engine is turning between 5000 and 6000 rpm at full throttle from a dead stop.

The individual springs on the clutch shoes determine the speed (in rpms) that the clutch will engage. A 1500 rpm clutch will engage when the clutch assembly reaches 1500 rpm which is not necessarily the rpms of the engine.

The weights in the variator more or less change the timing when the clutch activation will occur. Lighter weights will allow the engine to spin higher before engaging the clutch while heavier weights will cause the engagement to occur at a lower engine speed. Scoots generate most of their power near the maximum engine rpm (redline). Because of this, it's best to tailor the weights to keep the engine near (maybe 1000 rpm below) redline at maximum acceleration from a dead stop. This usually means going to lighter weights from stock. However, this can be a balancing act as going too light can cause a lose of top speed because the weights do not have enough mass to allow the variator pulley to close fully before reaching the engine redline.

Slider weights work well because they allow you to use a lighter weight than rollers (better acceleration) while not losing top end because of their design. They also do not require lubrication like some roller weights.

[daver]

Cruiser,
Thanks for the info.. makes sense to me.. I was going to ask what if any changes you had made to your variator since we have twins, but decided to just jump in and lower the average weight by 3g each.. No regrets whatsoever.. Next time I will go the slider option, but I couldn't pass up the hot deal I got on these rollers..
I was pleased that I found good quality grease inside mine, and not overloaded at all.. I used the Honda Helix manual for putting mine back together, and just used a minimum of good grease ..
I am also quite happy I am now cruising in the 5k range, long engine life, and much quicker throttle response than lugging around from 3-4k all the time..
Thanks again.. DaveR

[daver]

My riding partner has the twin to your bikes except in "boring blue".. I am wondering what weights you found in your bike's?.. His rollers haven't been touched, and would like to do some changing like I just did..
I know the only sure way to see what he has is to do the same I did and tear it down and weigh them one at a time.. He doesn't mind taking a chance and ordering some before we tear into it though, that way if we got the correct weight we can just install them, and be done with the job with one tear down...
Thanks, Dave