Installing new rear end gears

1. If you tamper with the motor in any way to de-restrict it, some dealers will completely void your warranty. So make sure this is a sacrifice you are willing to make.

2. ALL bolts and socket head cap screws are in metric! Don't try to work on your vehicle if you don't have metric tools, you will just end up messing up the heads.

3. This entire installation (Although it seems rather complex), took me only about 1 1/2 hours to complete from start to finish. It is rather simple to do, but it is a bit involved.

This posting is how to install new rear end gears.

The purpose of these gears is to give you more top end, while at the same time not changing your acceleration. The peak horsepower of you engine is generated at about 8000-8500 RPM. Stock, you are doing about 8500 RPM at 40-45MPH. From then on, you are increasing your RPM's, and decreasing your horsepower. The gearing just uses the full potential of your variator, and makes it so when you are at 8500 RPM your peak horsepower, you will be going 50-55 MPH instead of 40-45 MPH.

Lets Get Started!

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First start by removing the cover off the left side of you scooter.

This is what you will see behind the cover:

Remove the bolt holding the clutch assembly on:

Remove the Clutch bell housing and the clutch assembly with the pully:

Remove the drain plug, and drain the oil from your tranny. There isn't much oil in there, so it doesn't take very long.

Next you have to remove your exhaust to remove your rear tire.

Remove the two bolts holding on the brake callipers. I found it extremely difficult to actually remove the callipers from the disk. So I just left the callipers on the disk. There is enough hose that you can remove the tire without having to take the callipers off the disk.

With the exhaust removed, remove the cover on the back wheel so you can get to the bolt holding it on.

Remove the bolt holding on the rear wheel.

Remove the entire rear wheel from axle. Then remove the bolts holding the tranny cover on.

Once the covers bolts have been removed, gently pry the cover off. There is no gasket around the edges, there is a large o-ring instead. Be sure not to damage this when removing the cover.

When you pull the cover off, be careful not to drop any gears or washer shims. YOU WILL NEED TO RE-ASSEMBLE THE GEAR BOX EXACTLY LIKE TO FOUND IT. There may be several washers that are on different gear shafts. Don't loose them or mix them up! Be sure to note where each one was located.

Once the tranny is off, you will notice a large gear, with smaller gears located behind it. Just pull these gears out gently. They will simply slide right out.

These are the gears you should have pulled out.

Now for the most difficult part. You have to press the gear off its shaft. You can use a gear puller (Not an easy task), or if you have a heavy drill press, put a large socket behind the gear, and use the bottom of your drill chuck to push the shaft out of the gear.

Once you have pressed the gear off the shaft, you must now press the new gear onto the shaft. Be sure to line the shaft up perpendicular on all axis when you do this. You DO NOT want the shaft to be cock-eyed in the least when you start to press the shaft through the new gear.

Press the shaft through until the gear comes in contact with the smaller gear on the shaft. After the new gear is on, re-assemble the two gears into the gear box.

Now you need to remove the clutch shaft and gear from the swing arm. Simply use a rubber mallet and pound the shaft through the back.

Here is a comparison of the old gear and the new gear.

Now you have to put the new clutch shaft / gear in. Simply push it in from the back side of the tranny. A few wacks with the rubber mallet to ensure proper seating was needed.

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That is it for the gear replacement. Now you need to re-assemble the tranny case (be sure to put all spacers and washers back where you found them), put the rear wheel and exhaust on, and re-attach the clutch assembly. Put your drain plug back in, and fill your tranny case up with new gear oil. I found that tilting the scooter on it's side to fill was easiest. Once I filled it up, I uprighted the scooter and let the excess oil drain until there was no more oil coming from the fill hole. Put your cover back on and take it for a spin!

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Results

OK, Now I bet you are wondering what kind of improvement I got out of this... Well, I am not as happy as I hoped I would be.

My scooter will do 58-60 MPH max!! That is ducking down and on a flat or slightly down hill surface. While sitting in an upright position and on slightly up and down roads, my top speed that I can hold consistantly is between 50-52 MPH. After gear installation, I can now hold a consistant speed of about 55-57MPH. But my top speed has barely changed. Ducking down and on flat to slightly downhill roads, I can only reach a top speed of 63MPH.

My acceleation has changed slightly, only a very small decrease can be noticed... And I mean it is minimal. I have fooled around with my roller weights a little, but I think some more experimentation with weights and contra spring is required.

My conclusion is that the gears did what they were supposed to do, it raised my peak horsepower band up to a higher speed level and now I am able to hold consistant speeds a little faster, but I only have a 50cc motor right now, and I believe there is just not enough power there to get my top end up any higher.

I do believe that with the installation of a 70cc big bore kit, this gear kit would be a must have. although a bit dissapointed with performance results of the kit, it did help slightly on my standard typical travel speeds. A 5 MPH increase isn't too bad. But I am anxiously waiting to get a big bore kit and see what these gears will do then!

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VERY SPECIAL THANX TO SCOOTNFAST FOR PERMISSION OF USING HIS TUTORIAL. VISIT HIS SITE FOR MORE USEFULL INFORMATIONS. http://www.scootnfast.com