Evo Two Speed Transmission Maintenance

Maintenance of the Evo transmission is, like any other complicated mechanism, essential to the longevity of operation. With a bit of preventative maintenance and understanding about the workings of the system, this transmission can last a very long time.

In order to ease concerns over not being able to reassemble the transmission, a guide showing how to rebuild this transmission is available.

Re-tensioning the belts

Though all three of the belts will naturally stretch over time, the long, final-drive belt is the one which will be the only belt which will ever need re-adjustment.

If hear a loud ratcheting noise while accelerating on your scooter, it is most likely time to tighten this belt. It is only necessary to tighten this belt until it stops slipping. Tightening any more can increase friction and put extra stress on the belt and the transmission. For information on the operation of this tension mechanism, see the 1-Touch Tension System article.

The two short belts inside inside the transmission can be run much looser than the final drive belt. By keeping these belts loose, you both keep unnecessary stress and friction out of the transmission. This will reduce the amount of heat created by the belts and increase your top speed.

Cleaning and polishing the 2nd gear clutch plates

The 2nd gear pulley and parts

The lower 2nd gear pulley rides on a large 6204 bearing. Unless the transmission has been rebuilt with sealed bearings, ths bearing will have metal shields which will not entirely keep the bearings lubrication within the bearing itself. Over the first 50-100 miles, the clutch will be sprayed with excess lubrication from this bearing. Due to the buildup of grease and dirt, this clutch system will eventually stop grabbing effectively. This problem can be alleviated by simply cleaning your clutch plates.

Cleaning the clutch plates and pads is a very simple, but necessary process. Simply disassemble the clutch and clean the plates with a non-oily cleaner. Brake cleaner and carb cleaner are fantastic. If there is any corrosion or noticeable wear on the plates, the my also need a light sanding. Wet-dry 400 grit should do quite well to get these plates back to the way they should be. The smoother these plates are, the more effectively they will grab.

Replacing the bearings

Over significant miles, this transmissions bearings will wear to the point of which they must be replaced. A failing bearing often makes a distinct grinding or clicking noise within the transmission.

If a bearing is not replaced before it fails, it could do serious damage to the transmission. A full set of sealed replacement bearings can usually be purchased for less than $50 from various online bearing retailers.

The bearings inside the transmission are as follows:

  • 4 x 6000 10x26x8 Ends of top shaft and belt guide (C4-5 3COB06000A 10x26 BEARING)
  • 2 x 6001 12x28x8 Inside cams of top shaft (C4-3 3COB06000A BEARING 28x8)1
  • 2 x 6002 15x32x9 Inside caps of bottom shaft (C6-2 3COB06002A BEARING 30x15)2
  • 1 x 6204 20x47x14 Inside lower 2nd gear (C8-3 3COB06204A BEARING 20x47)
  • 1 x 1910 10x19x6 Inside cover clutch plate (C8-5 3COBL1910A 6x19 BEARING)

Re-grease the 1st gear bearing

1st gear pulley with fresh grease pressed into its pins

Though the 1st gear one-way bearing inside of the lower 1st gear pulley is relatively shielded from the elements, it is important to clean and re-grease it every 1000 miles or so. In order to effectively clean the gear, soak it in gas overnight and clean out whatever remains with a non-oily cleaner like brake cleaner or carb cleaner.

Viscus joint greases and chain greases seem to do quite well with this bearing. It doesn't appear that it is possible to get too much grease pressed in, so press in as much as the bearing will accept. Any extra will simply spin its way out during operation.

Before getting back on the scooter, make sure to test out the operation of the one-way bearing and distribute the grease by simply rolling the scooter forward in 1st gear for 10-20 yards without the engine running. The bearing should spin on the shaft to set itself up.

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