Variator, drive belt, etc By sjrainsford (Read 2,086 times)

[sjrainsford]

Following on from my previous thread titled New Scooter, New Concern.

I've got a bit further now and related my vibration to be most likely coming from the drive belt area. So today I removed the cover for a little inspection.

The drive belt is in great condition actually, as would be expected from a bike that's only done 1000 mile from new. I ran it up, and noticed it does jump around quite a bit though.
After a closer look around, I noticed the wear line on the variator face. It looks like the belt isn't riding all of the way up the variator. I'd say the wear mark is perhaps 5mm from the outer edge. Is there a common cause for this? Perhaps my variator weights are a little light? Or is that how it's supposed to be? I kind of expected it to use the full area of the variator giving me the tallest possible gearing. It's currently got 12gramme weights from what I can tell.
Have also fitted a tacho a few days back, and at 45mph i'm doing about 7200rpm. Then at 50mph I'm doing 8000rpm or there abouts.
Another thing I noticed was that the variator assembly and weights didn't seem to be very smooth in it's operation. So I took it apart and gave it a good clean and a light greasing. The tube that sits in the middle of the assembly allowing the variator to slide in and out was very dry and stiff in it's movement. Must admit, it runs a lot nicer now I've done that. The belt isn't climbing any higher though I don't think.
Sorry it's a rather large post. Looking forward to your experiences.

[sjrainsford]

Having a look on the net it seems it may be an issue with the shorter cased models, such as mine running 10" wheels? The belt perhaps isn't long enough to allow it to travel all the way up the variator. It is tight when fitting it I noticed.
Its currently a 743-20-30. Ive noticed 800-20-30 ones available, but would you guys think thats a little too long?

[kz1000st]

Yes 800 is way too long. I think your cleaning is about right and if you want more top speed 15 gram weights might help.

[sjrainsford]

What setup are you running on your Milano KZ? I know it's a 150, but it looks like it's based on the ZNEN ZN125/ 150 frame so is basically a similar bike to mine. What sort of cruising speed will it happily sit at etc?

[kz1000st]

Basically I run mine at 45 mph. It puts much less strain and revs on the engine. My 135 lb. ( don't ask me what that is in Stone or Kg., I don't know) wife has taken it up to 50 mph for long stretches and swears she didn't top 55 mph, unless a truck passed by and she got sucked in his draft.

It's stock with the original rollers (I heard they were 14 grams) and variator. In all the years I've been on these forums 45 mph is the general consensus of a safe speed. I figure, here's the math. At 6000 rpm the engine is spinning 100 times per second, at 9000 it's spinning 150 times per second. These things aren't MV Augustas, Triumph Thruxtons or Honda CBR 1000s. I think 45 mph and about 100 times per second from an inexpensive machine is a pretty good deal.

[sjrainsford]

Thanks for your replies KZ. Looks like mine is similar to yours. It seems to like sitting at 45mph. I may experiment with heavier rollers to see what effect it has, but it generally feels geared fairly well. I guess in reality I'd want to alter the final drive for a higher cruising speed.
When I look it up on our Chinese scooter parts supplier the ZNEN ZN125T-E is listed as 17gramme rollers standard, with 12 optional. Mine was 12 from new.

[kz1000st]

Besides the heavier rollers and rear gears several people bought 115mm variators.

www.buggydepot.com/store/index.php?main_page=product_info&products_id=11

The hot setup was one of these with 15 gram rollers.

[sjrainsford]

That's rather interesting. May look into that. And I guess, if they've been using them with the short case engines, the belt must be long enough to travel up the extra area?

[tvnacman]

this one is in stock cheaper
www.testedscooterparts.com/product_info.php?products_id=10565810

and a stock is 107mm diameter , mine comes with your choice of rollers , we can sub out the rollers with an upcharge to sliders .

John

[sjrainsford]

Do you ship to the UK Tvnacman? It seems there's a lot more parts and experience of the GY6 available over the pond. There isn't much available here unless you want standard parts, or happy to try your luck on ebay.

[sjrainsford]

Right, a bit of an update. My heavier rollers (15g) came today so I fitted them. With a little more inspection, I noticed that my current 12g rollers are maxing out on the variator assembly anyway. So I don't really need heavier unless I want to lower my rpms for a given speed. I've done this in the interest of fuel saving anyway.
It looks like the varistor is touching the drive face so is at it's maximum travel, therefore my belt is never going to climb any higher. So, my next step looks like a performance variator. Tvnacman mentioned that KOSO one and it looks like they're available over here. Does anyone know if they're actually larger than the stock 107mm diameter one I currently have? And are they adapted such that they can actually go closer to the drive face meaning the belt will actually climb higher and use the extra diameter?

Basically I'm currently at the limit of my gearing so it's either this or changing the actual gear ratios.

[sjrainsford]

I'm guessing there's not been much experimentation with performance variators on this site, or my post has been missed.

Anyway, I've gone ahead and ordered a KOSO one from china. It's only a cheap one, but that's the whole idea with my bike. A cheap bit of fun and cheap to tinker with! Will post up my findings including what sort of RPM my engine runs at etc.

Also, in case anyone wants a tachometer that is easy to fit for when doing roller weight changes etc, I can recommend this one. It can be fitted temporarily or in a more permanent way. It's self powered, and there is one single wire that exits from it. All you have to do is wrap that wire a few time round your spark plug cable. Then it has a couple of options on the screen to select how many times the plug fires per revolution, so it should work with two and four stroke single and double cylinder engines. If you guys feel it's worth it, I'll gladly make a second post with a short write up on it.

www.ebay.com/itm/Spark-Plugs-Engine-Digital-Tach-Hour-Meter-Gauge-Tachometer-Motorcycle-Bike-ATV-/161064983664?pt=LH_DefaultDomain_0&hash=item2580389c70

[kz1000st]

Not missed, I just only have second hand information on them. I can't remember the name of the variator but it had variable pitch on it, like the J. Costa variator for 250s. Kliff put one in his scooter, put in 15 gram rollers and went out and did 62 mph, true speed, on it with no other modifications. That wouldn't be a big deal except Kliff was a 250+ pound guy. I would imagine a less large person would do even better. If someone needs more speed than that, a bigger engine is in order.

[jct842]

was it a polizi or some thing like that. I put one on my 150 and I was very happy with it. I had light weights because of the hills here and when I ran it up to 55 I was running around 6800 rpm. as I remember.

[sjrainsford]

Cool! I'll let you all know my findings. Its coming from China so will probably be a couple of weeks before i fit it.