CVT/clutch issue

[illnoise]

I know next to nothing about CVTs, so bear with me here,

Lately (this is a Blur 150) occasionally (once or twice per 10-mile commute) when I decelerate, i notice what feels like engine braking at first then a bit of a jolt just before I stop. It almost feels like a sticky clutch, so I'm wondering if the belt is sticking on the outside end of the pulley longer than it should, then once I'm going slow enough it slides down to where it should be suddenly. But it could be something totally different, that's just a guess.

Any ideas? It's a 2006, but pretty low mileage (2200 miles?), I have a few scooters and don't ride any of them much. No mods, and I ride pretty conservatively...

I'm about due for an oil change, but I was hoping to spend the rest of my life never cracking the cases of a modern scooter engine.

Thanks!

Bb.

[Lostmycage]

You don't have to crack the cases, but you should open the CVT up and blow it out with some compressed air. Over time belt dust and the clutch pad dust builds up and can cake up in the clutch which will cause exactly what you're feeling.

There's (about- it's been a year) 7-9 8mm bolts holding the CVT cover on. Use a non-mar rubber mallet to smack the cover enough to get it coming off. There's a paper gasket in between that you should be aware of, try not to let it rip (but don't sweat it too much if you do rip it, just put it back in place when reassembling and it'll keep acting like a dust shield). Use an air compressor with a blower nozzle and give it a dusting. Don't forget a dust mask and eye protection, that stuff's pretty nasty.

This is one of those things that really should be in the owner's manual if at the least the service manual.

[Rippinyarn]

What he said, and my tip to add is to take a piece of cardboard and draw a rough outline of the tranny case on it. Poke holes in it where the bolts go (approximately). As you take them out, place them in the corresponding hole for the case. This way, you'll know exactly which bolt goes in which hole, as some of them are invariably shorter/longer than others. I learned this the hard way on the Kymco. If you are working on multiple scooters, be sure to label the pieces of cardboard. When you are done, stick them behind something so that you can waste precious garage time tearing things apart looking for them when needed.

I also use a sticky sealing substance called Hylomar to stick one side of the gasket to one sealing surface. Using small amounts of this stuff both makes taking the cover off easier and preserves the original gasket (by keeping it stuck to one side). The have tubes of the stuff at your local auto parts store. One tube will easily last your lifetime.

And wear some breathing and eye protection when you're blowing the stuff out. You can never tell!

[Lostmycage]

While normally a good bit of advice, it's excessive in this instance. On the Blur 150's CVT case, all the bolts are the same length. Still good practice.

I'm not sure about the Hylomar as I haven't used it, but the paper gasket sticks pretty well already due to compression and heat cycles. Adding a secondary adhesive to the mix might cause the paper gasket to get torn more easily. It's basically just a dust shield. Still a good idea to keep it one piece, but no cause for spilt milk if it gets torn.

[illnoise]

Awesome, good stuff, thanks. It's awesome how much "advice" i spout out here while knowing f-all about modern scooter engines, ha.

Bb.

[babblefish]

Sounds like one of two things:

1) Your clutch is sticking engaged, then suddenly releases when the load on it decreases - as when you slow down. This can be caused by one of two things:

a) The clutch shoes are worn out and allowing the clutch arms to overextend. This in turn can be caused by constant heavy acceleration from a stop, carrying a heavy load or both.

b) The clutch return springs are either worn out or one may have come off.

2) One of the variator plates (front or rear) is sticking then releases when the load on it decreases. They are suppose to slide back and forth on their respective shafts, but if they get dirty (like from belt dust) they can jam.

[killbilly]

Interesting.

My Blur 220 does the same thing, kinda. When decelerating, as I approach a stop, there's a bit of a kick. I just assumed that it was normal clutch-disengagement. Wondering now if that's normal.

[babblefish]

It is normal for the clutch to remain engaged for a bit when you let off the throttle. When it finally releases, the scooter may excellerate a bit due to the sudden lost of engine compression to slow it down. This is the small "jerk" that you feel and is perfectly normal.

[davelhunter]

Agreed. My 220i does the same thing. It's normal. It's just the clutch letting go.

[illnoise]

I updated the thread subject to more accurately describe the problem, for posterity…

As suggested (thanks!) I (and when I say "I," I mean "My friend with air tools that I happened to run into this afternoon) pulled the CVT cover and blew out all the dust.

Interesting: We took out the clutch and took off the large nut that holds it together, and it didn't even spring apart, so we put the nut back on and tapped it with a mallet until it popped apart, then loosened the nut again. Dunno if that was part of the problem or just a coincidence

The shoes looked more worn than I'd expect for the mileage but not terrible, and I didn't have replacements so back they went. The springs were all fine. We put it together with a teeny bit of grease on the shoe pivots and put it back in. (We ran out of time to pull the variator, we just blew it out with air best we could and bolted everything back up. Just had time for a short ride around the neighborhood and it seems to have helped, but I won't know for sure until I commute, it seemed to be a bigger problem coming down from higher speeds.

Thanks again for the advice, everyone.

Bb.

[charlie55]

You may have noticed that each of the clutch pawls has a notch in it which lines up with a small, round rubber bushing within the clutch assembly. This is another spot that could be made happier with a little grease/silicone. Just a dab on the bushings lets the pawls seat back to their "retracted" position more easily.

[Lostmycage]

It sounds like the main spring was binding and that snap you'd feel was it becoming unstuck. The only thing I can think of is that it was put on under excessive torsion: when you squeeze it together, you'll notice the shoe assembly wants to twist as the spring compresses. If you don't align it so that the two assemblies line up, in other words, if you just force it, then the spring is compressed and going against it's compressed shape. That could cause it to not rest straight and put uneven pressure on the shoe assembly, which could cause it to seize up as you're describing. That's my guess anyway.

There's actually a little part you can put in there that will help with that, it's a bearing seat that let's the spring spin as it likes which keeps it from going out of shape.

[illnoise]

Just a dab on the bushings lets the pawls seat back to their "retracted" position more easily.

Yep, we greased those too, I meant to ask if that was stupid or not (I greased the rollers on my garage door once… bad idea)

Bb.