In this video series I was looking for possible cheap alternatives to an over range rear pulley for the Minarelli / Jog / 1E40QMB two-stroke scooter engine. Along the way I tried to include information on other CVT topics that may be useful, in addition to detailing what was done to make each pulley fit my Chinese scooter's 1E40QMB transmission. It's all available in 1080p so go full screen!
The whole video in all parts is about 1 hour and 13 minutes long, so if you are looking for something specific check out the listing below for quick access.
Part 1 (24:53) 0:14 What is an over range CVT? 2:27 Malossi Over Range CVT Kit 6:28 Using Spacers On The Drive Boss 11:47 Morini Rear Pulley 14:59 Elongating Torque Driver Grooves
Part2 (32:02) 0:00 Modified Stock Rear Pulley 4:11 Modifying A Stock Front Pulley Fixed Half 11:13 Stock CVT 14:45 Piaggio Rear Pulley 20:16 CVT Cover Clearance 27:12 Flat Centered Front Drive Face
I've also created a few PDF documents for anyone interested. This one is basically my notes for the setups tested in the video. The same test run info you'll find in the video, but available for quick/condensed viewing. www.49ccscoot.com/manuals/CVTProject-TestInfo.pdf
Here's a formula that may help find an appropriate belt length based on additional travel desired with a current belt. Thank you to FrankenMech for posting this.
[( additional travel x Pi ) / 2 ] + original belt length = new belt length
This could be used to help you make an educated guess at a belt size for new pulleys or to find a belt that may allow for full travel of an existing setup. Here's an example :
Let's say that I put a mark across my variator and then did test ride at full speed. I found that a 5mm mark was left on the outer edge of my variator's drive face. Heavier rollers/sliders or a softer contra spring didn't change that and there appeared to be no restrictions in the CVT components that wouldn't allow them to open or close completely. I could use this formula to help me find a belt that may allow full travel of my pulleys and perhaps see some extra speed.
5mm is my additional desired travel on the drive face The belt is 788 17 28; the first number being the length of the belt in mm (788).
[ ( 5mm x 3.1416 ) / 2 ] + 788 = new belt length ( 15.708 / 2 ) + 788 = new belt length 7.854 + 788 = new belt length 795.854 = new belt length
It's doubtful that I'd find a 795.854mm long belt, and maybe not even a 796 or 795mm long belt, so there likely needs to be a bit of compromise. I would look for a belt close to the first number and ideally the same as the other numbers in the belt specs.
My original belt in this example is a 788 17 28. I would look for a ~796 17 28. The second number is the belt width. The last is the pitch or angle of the sides of the belt. If your current belt works well, most likely you want to use them, as diameter of pulleys does not in itself change the width or pitch of belt needed. Width should only be changed if the opening and closing distances of your pulleys is changed. Pitch should only change to correspond with different drive face angles.
Last Edit: Oct 10, 2016 14:47:45 GMT -5 by 90GTVert
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