Variator doesn't return to low "gear"

Thanks, in the next few days I might try to use my friend's BWS' boss to see if the problem gets fixed

 

Alright, I got a used boss which wasn't too worn out and today I replaced mine with it. Turns out the rollers I was using have some flat spots and deep indentations with just a few months use! Anyway, I replaced the boss and put on some other rollers I had as a spare, 5g (up from 4.5g), and now he's how to scooter operates:

When taking off, there's still a huge spike in RPMs (really, all the way to the rev limit range) followed by a drop to just a little lower to the power band, which I guess is because the rollers are a bit too heavy. Then it works as intended, having good acceleration and all that.
When slowing down it now "downshifts" good too.

So the remaining problem is the RPM spike. What could cause this? I'd say clutch slipping, but the bike still takes off pretty fast so I guess the clutch is engaging properly... Ideas?
Another thing worth saying is that the first times I messed withn the CVT this also happened but after just a few days it would return to sloppy cvt operation, so it might happen again...

 

Is the belt the right width for the bike? Sounds like it may be slipping a bit til it heats up and grips the rear pulley properly due to it being a bit thinner than it should be. Might want to try a wider one, only a couple of mm though, not too much.

 

Did you see any signs of ware on the roller plate?
As far as I can gather with my limited knowledge, speed and acceleration is really affected by the cvt set up.
By process of elimination, I hope to get everything working optimally , first I changed the belt for a polini Kevlar and it works like a dream. Now I´m focusing on the variator, I´m going to check the rollers again tomorrow to see if there are signs of ware, if so then I´ll change the whole unit. Finally I´ll check the clutch(housing, pads, springs etc) and see if any of that needs changing.

My scooter is performing a lot better now although I still have a sneaky suspicion that my clutch needs looking at.
I wouldn´t hesitate in checking it except I need to get a clutch tool to re-fit the contra spring, they seem very pricey for what they are.

Anyone got a link to a cheapish one (max 15 quid) please let me know. The cheapest I could find was 25 quid plus postage.

 

Forgot to ask, you mention the boss...which bit is that?
Cheers

 

My 3 in one tool was only 20posted bud

 

And that does clutch variator and has a big spanner end for taking the clutch apart

 

I'm 100% sure this is the right belt for this bike. Also it still has that spike even if I've been riding the scooter for like half an hour, so I guess that rules out that theory. And as I said, I'm pretty sure there's nothing slipping since it takes off with a lot of power, matching the rpm, and that power then drops when the rpms do

 

this symptom is really common when the variator starts to become worn and especially with standard variators- often it isn't noticeable with a standard exhaust because the engine makes power across a broad powerband so the fact that the variator isn't holding the revs very steady doesn't matter too much- it can become really pronounced though with an aftermarket pipe fitted because of the narrower power band-
if you don't have a decent aftermarket variator on there I would try one - any known brand should be fine but avoid the newer polini hi-speed on minarelli where the above is the problem

 

So that should be it then, having a stardard and pretty used variator, and a sports exhaust (one of these days I gotta take a picture of it and post it here to find which one it really is, all I know is it's a gianelli one, but can't find the exact model on the web... it wasn't fitted by me btw), even tho I don't notice anything wrong with the variator, I guess the rollers ramps are f* up... I'm going to have to tear the whole engine apart anyway to change crank bearings and seals and probably fit a new cylinder kit and crank all together, and since I was thinking of fitting a new variator anyway...
thanks

One question: It'll probably still take a while to actually fix the engine.. Do you think if I swapped the variator now it could become damaged due to the huge play my crank bearings have? (you can actually hear the crank hitting the bearings if you try to move it side to side)

 

Do you mean you can wobble the crank side to side if you grip the end of the crank ? that must sound terrible when it runs!
I would sort that out right away before doing anything else, you're very much on borrowed time already if I understand you correctly. Also it will probably have damaged the crank seal which will consequently be unlikely to be sealing properly and compounding any running problems.

 

Yes that's exactly it (it sounds ok tho, yu can just hear a small whistle at certain RPM), and yes the seals are in pretty bad shape too (you can even notice the tickover speed changing from time to time due to leaks). Thing is, I still don't have the money to do everything I want to do to the engine, and I'd like to do everything at once, and that is when opening the engine apart...

 

Cheers mate, I had an inkling that it might be that bit but I didn´t know for sure, thanks again

 

Could you send a link(if it´s ebay), the tool I was really thinking of, was the one which allows me to compress the clutch when changing the contra spring. I´ve got the tool for the variator and it was an excellent investment but the 3 in 1 tool would be a lot better because I don´t have a spanner big enough to tighten/untighten the big bolt.
Thanks for letting me know about YET another item that can´t live without .(I don´t know what´s costing me most, the parts or the tools ) At least once I´ve got the tools I need, I won´t have to fork out for them again.

 

http://www.ebay.co.uk/itm/Yamaha-Ne...91?pt=UK_Motorcycle_Parts&hash=item5d43571297
Get one trust me

 

Lovely , thanks.

 

I'd love to know how this problem turned out— was the issue ever fixed? The final culprit ever found? I hate it when threads like this die before I get to know what happened. Please advise, if you are able, Brgil96.