El Cheapo Variator Report  By  rcq92130 (Read 9,676 times)

Rcq is doing a great job with his research ! I only have a cell phone for internet right now so I'm really glad he is doing this .

I now believe its probably best to buy all CVT and engine parts from PR. Scooter racing is very big down there and they would never use this junk being sold in the US. Many of these so called koso variators come with gouges , nicks and scratches all over the variator face. The DLH variator uses the same back plate with the same type print , checkered flag and coating. I would not be surprised if they are exactly the same all round. The shops in PR have a reputation to uphold and a quality good enough to supply the professional racers. The place I usually order from down there didn't even have these cheap Koso's when I checked. They had a few good looking variators from $40-$60 and some a little higher. They even have a black 117mm variator that I would like to try out. All the variator I looked at aren't as thick at the center where the boss inserts "just like my first koso" . I will soon order a new one and will have to post the results " performance wise " I have a feeling this thread will be active for a long time.

So, geh - the thought I had with this is that maybe all of us together can, over time, pull together enough data that we can take care of ourselves and make sure we get what we want and need.  That's pretty difficult at this point.  Best one can do is buy from a trusted source - mine are the same as yours (Gy6Racing and John) - but even then we are dependent on someone else looking out for us when we should look out for ourself.

That's why I suggested to JerryScript this morning the possibility of starting a table in the "data" section of this blog - a place where we can start listing all the variators any of us have and their measurements.  Might take a while but if every so often someone else would add another line for their new variator I think is due course we would have the best library of variator data in existence.

Maybe that's a dumb idea - so I'm asking for your opinion.

Great idea , that way everyone gets what they ask for .

I agree he's doing well and it should be a focus for us.

A couple of things I will add is that the "ramp depth" is not a good way to measure. The weights don't ride on the hub. Making it longer just reduces the travel, but it's a non issue because all that matters is that the back plate ramps are touching the weights. That means that the longer you make the hub, the thicker the front of the variator needs to be. The proper way to measure the effectiveness of the ramps is to measure the plate ramps, rollers, boss, variator pulleys, clutch shift angle (that curved hole in the clutch hub), and clutch main spring, as one unit, along with the engine. 

Even then, as we have all seen, the system can be so highly geared that it becomes poorer in performance, because what good are higher gears if you can't pull the load? That's why we've had to reduce our weights so much on some of these variators. Even then we may not have the power to reach maximum rpms. That's why it's nice that the Dr Pulley variator came with shims, so the rider can reduce gearing if need be.

It's hard to nail this stuff down for all scooters because rider weight and riding style are factors too. My preference would be a variator that goes all the way down into the pulley, for best off the line acceleration, keeping the rpms at maximum torque and power, making the belt go just high enough that I can still reach max rpm. That may mean a variator that actually never closes all the way.

Let's say you change the cam and give yourself more power at certain rpms. Now your variator needs to match that. 

The ramp "depth" depends on the diameter of the variator. The larger the diameter, the more distance the pulley must move in and out. If the belt is 120mm wide, then you want the pulley faces, at the bottom and at the top, to be roughly 120mm apart so that the belt can travel the entire face of the variator, or close to it.

The easiest way to test a variator's travel is to assemble it and mark it and run it. Then you'll have your two diameters. RCQ talked about travel. Travel is not the distance from the ends, it is the distance between the two marks. 

On the DP variator the travel is:
(114.7 - (3.56*2))-(3.76*2)=(107.58-7.52)=100.06mm /2=50.03mm per side

(But this assumes that the pulleys are all made the same. That's why knowing the actual diameter at the bottom is important, not the "dead zone".)

We already know this is not going to be accurate but let's continue.

On the OEM the travel is:
(107.4-(3.96*2))-(4.14*2)=(99.48-8.28)=91.2mm /2=45.6mm per side

And on the EC the travel is:
(115.2-(5.94*2))-(4.57*2)=(103.32-9.14)=94.18mm /2=47.09mm per side

I see those numbers don't match RCQ's so one of us goofed, but again, you need the inner mark diameter to know the real travel. The good news, assuming the variators are all cut at the exact same angle, is that he can directly measure the distance between the two marks for a comparison. He can get the real travel by measuring the outer mark diameter and subtracting the inner diameter.

The other difference is gearing. The outer marks show us which pulley has the highest gear. That would be the DP at 100.6, the EC at 94.18, and the OEM at 91.2mm. That's 4.7mm per side difference between his OEM and the DP. I think he could add 2.35mm or about .094" of shim to make the gearing the same at top end. He has 3.76mm of inner dead zone, but he could only add 1.88mm or .075" of shim before his belt hits the bottom of the variator face. Don't hold me to that. As I recall, at 30 degrees pulley, you get about 2mm drop for every 1mm of shim. If those numbers are correct, then he could drop the belt to the bottom of the variator face and his top end would be 46.54mm - 45.6mm = .94mm higher than the OEM. So he'd get a higher top speed with the DP if his engine can pull it, and we need the actual inner mark diameter to see how it would affect the low end gearing compared to the other pulley. 

In other words, he needs to dump his travel figures and use the diameters to get the true travel, then he can figure out how shims would affect performance on the high and the low end. We already know he can get more top end with the DP, but now we need to know what the low end will be, and we need the inner mark diameters to find out. 

Good work RCQ! You too Geh!

I'd be glad to go in depth on variators. They are my favorite part of the scooters. I was trying to express how complicated the shapes are, especially the ramps, and how the ramps, back plate, weights, boss length, and other measurements interact, so that it's difficult to examine any one part alone to figure out which one is "best".

To measure the inner diameter, lay your calipers across the pulley from inside mark to inside mark. No need to worry about the angle. The view on the left side of the picture below shows the best way to measure. The view on the right is just for clarity. Same for the outside marks. The outside minus the inside diameters will give us the belt travel, tell us what your lowest gear is, what your highest gear is, and if you also include  measurements of the OD and the face ID, not the flat part, we can then tell how much we can gear up or down with shims, or by cutting the boss, or even the pulley for that matter. This way you can get a real comparison between the three variators and also find out if you can make the other two perform as well or better than your OEM.

For my own analysis, I'd be grateful if you'd throw in those inner mark diameters so I can continue studying the variators you have. That's very cool of you to post all of that.

(btw I have considered making the face a different angle because the belt mfg said they can be X amount of angle from nominal. That could be useful. A compound angle would be cool but may wear the belt out by flexing it from one angle to another over and over again.)

Thanks RCQ.

Yes I'd love to do a tutorial.
I can show you how to measure the ramps if you want. 

Here's what I need to continue my math on these three variators:

Maybe at some point we will be able to tell what type of variator we have by weighing it or by how thick the face is , or both