Dr. Pulley sliders - rev problem?

[ktienation]

Hello,

I have installed a long time ago a set of dr pulley 14g sliders. My downtown's millage is currently about 7,5k miles.

Before installing the sliders, when starting at WOT the engine reved to about 6k. and stayed there untli 65-70 mph. After installation of pulley sliders it changed to about 6,5k rev at WOT and it was perfectly normall (thats the values everybody declares with those sliders).

However, recently i noticed, that when starting at WOT the engine revs to aabout 7 - 7,5 k rpm for a short time to drop soon after to 6,7-6,9k.

I will add, that it cant be due to the wear of the belt / clutch as this component were exchanged when the odo indicated about 6,5 k miles...

Any idea what might be the cause of such?
 

[windwheeler]

So, you are saying you have not changed ANYTHING since installing the sliders? It changed by itself?

Actually a higher starting rpm should give you a positive effect, an even better acceleration pull.  Do you feel that?

Does it then settle to "normal" lower rpm's at e.g. 70 mph?

[ktienation]

Exactly. THe possitive effect is there and i can feel it. With stock rollers WOT was 6k rmp, and dr pulley was 6,5k at WOT (what is in fact in compliance with the reports of other users).

Yes it settle to lower rmps when stopping to accelerate.

What bothers me, is the fact, that after instalation, for about 1-2k miles the rpms were as they should be (6,5k at WOT) and just recently they started to increase and i have no idea why. Nothing was changed since that moment and therefore i am seeking for the reason of such state as i feel it shouldnt be that way.

[windwheeler]

I have noticed changes of Dr. Pulley weights on my other scooters too, but nothing to be really concerned of; just changes.  It is usually related to getting a bit different friction on the Dr. Pulley weights in the variator, so it takes higher rpm and speed to change.  Cleaning would help, but then it will probably go back to the same after a while.  Only way you may stay long term in the 6.5K range is to install a bit heavier weights, e.g. +2 grams more, and try what it will do long-term.   

[ktienation]

OK, thanks for the reply. Its not that it bothers me the high revs. I was just thinking that this might be some loosen nut or something else that could lead to transmission damage.

[windwheeler]

As long as it comes back down after e.g. 50mph, or without WOT it will not matter

[de dee]

  if you did not torque the nuts and put lock tight blue on maybe it would be a good idea to check the nuts , and you could measure the belt at the same time, and clean a little,better safe than sorry, 

[windwheeler]

Good point De Dee.  A re-check is for sure a good thing to do even if it is just for peace of mind.

[zombie]

It could also be the sliders are wearing. Id pull the var, and check. Sometimes the ramps are rough, and it will pull plastic off quicker than some others.
Maybe the clutch pulley is not fully opening? Sticking at some point?
Maybe the tire pressure was low when you first installed them?

[ktienation]

Thenk you guys for all the replies.

What comes to my mind after reading your opinion is: maybe the vario should be cleaned and maybe the vario nut is a little loose. the clutch is almost new (less than 1k miles) and everything was installed in a kymco authorised workshop (so the nut mounted there was brand new. However, the vario is now about 7,5k miles old and it was removed a few times and assabled again without loctite or anything similar, so maybe here is the problem (however, the nut was always torqued with a dynowrench to the value recomended by the manufacturer). The sliders are also rather new as i am using them now for about 3 k miles.

[zombie]

You know... I would pull the clutch, and disassemble the pulley. There are a few youtube vids to help. Mainly in the 50cc scooters but the process is exactly the same. The pulley 1/2's have a pin, and slot that allows a small amount of twist. If the grease is worn out in there the 1/2's can stick or wear a groove into the pin.
I suggest taking it all apart because you would never be able to open the pulleys by hand w/ the main spring installed.

It doesn't sound like anything is slipping, more like something is just not seated right.

Just an afterthought... Maybe the Tach has jumped? There are cheepo multi meters that have inductive tachs. built in. Just to verify yours...

[ktienation]

Nah, the tach is ok, as when i.e. riding at 60 mph the revs are where they should be. Same with any other speed. This rev increase applies only to WOT acceleration.

The pulley 1/2's have a pin, and slot that allows a small amount of twist. If the grease is worn out in there the 1/2's can stick or wear a groove into the pin.
I suggest taking it all apart because you would never be able to open the pulleys by hand w/ the main spring installed.

I think i dont understand what u mean in here. Are you talking about the sliders or some part of the clutch? The clutch i have is almost brand new (less than 1k miles on it).

[zombie]

I am talking about the rear pulley assembly. The clutch has to be removed to inspect this.

Don't assume because the clutch is new, there are no issues there.
This video sucks but toward the 14:40 mark he pulls the clutch off to find his pulley set is toast. That's the part I am talking about.