ATV On-Line crank bearings - - ATV at Off-Road.com

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ATV On-Line crank bearings

Publish date: Oct 1, 2005
By: ORC STAFF
Source: ATV at Off-Road.com

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I guess your here because your interested in learning the fine art of replacing crank bearings.

Well you have come to the right place !

To start with ,I'll let you know now that we will NOT cover all the details. That is what your manual is for . It would be impossible for me to cover every engine made in one article. So I won't even try.
Some people may think that this is an extremly difficult thing to do. I don't think so. Is it time consuming and detailed work ? YES !!! Do you need to have the correct tools ? ABSOLUTLY !!!
If your not sure about what tools you may need , all you need to do is purchase the manual for your ATV, Then READ IT ! It will tell you all the tools and supplies you need for doing the job right.

We are going to start with the simple stuff first. With out going into all the details (This is why you bought a manual RIGHT!) , you will need the remove the engine from the frame right ? Well before you do that. Here's a little tip. Get the motor ready to be removed from the frame , but while it's still bolted in , remove the covers from both sides of the motor. Remove the clutch and clutch basket from one side , then remove the flywheel from the other. REASON...they are easier to remove while the motor is still in the frame.			Once I have the clutch and flywheel out I put the side covers on with 2 bolts so as not to lose or damage anything when I pull the motor out.
	Following all instructions in our manual and using the proper tools , we were able to "Split" the cases easily . As you can see in this photo we used great care in doing this. We were so carefull we were able to seperate the cases without any of the transmission components coming out of their places. AGAIN I caution you , if the manual calls for certain tools, buy them and use them. I know it can be very tempting to try use a regular phillips screwdriver when the manual calls for an impact driver. Doing so will only cause more problems. USE THE CORRECT TOOLS !!!!!
Once the cases were split , it is just a matter of sliding the crankshaft out of the other side. ( You can use an aluminun hammer to "TAP" it if necessary )		You will notice that we still took great care in doing our best to not let any of the transmission components leave their position , even though we had to tap the crankshaft out of the other side of the cases. Even if something did come out of place it's really not a big deal. You still have your manual to show how it goes back together, right ????
OK ! Here's the part where you need to use some care and caution !! You first need to remove the old seals. Not too tough , just use a screwdriver to pop them out. With the seals out , now you need to remove the old bearings. Lay the engine case down on a flat surface. Then using a socket thats the SAME size as the outside bearing race , you can use a mallet to carefully tap the bearings out. The trick is to tap them out STRAIGHT !!!!			The reason for using a socket the same size as the outside of the bearing is because if you tap on the inside race of the bearing , it may just come apart.
	AGAIN CAUTION is in order !! Now the old bearings are out , it's time to install the new ones. The MOST important thing to do is to make SURE the new bearings go in straight . If the bearings go in at an angle this will cause problems down the road. (Like premature bearing failure) . Start by placing the bearing into the case. Then using a flat piece of steel or wood , begin tapping lightly to insure the bearing goes straight into the case. Do NOT hit the bearing directly , this may damage the bearing causing it to fail.
Once both bearings are in place you can the install the seals with a rubber mallet making sure not to damage them. Damaging the seals or installing them improperly may result in an air leak into the motor. An airleak may cause a lean condition which may damage the motor. As long as you have the crank out , check it for being true. Now you can begin the process of putting it ALL back together again. I said I wasn't going to get into details, but Don't worry , as long as you have your manual , you can do it. Just be sure to follow the manual and tighten all the nuts and bolts to the proper torque specifications.