Hi everyone. So I have a 88 Moto 4 225. Just got it, and did some work on it to get it running. Right now I am hearing a whining noise when driving it. The noise increases when I give it gas, and when I leave off the throttle, the noise goes down. Sounds like a whining a truck would make. I jacked up the front and no noise from the wheels. Jacked the back up and put it in grear, give it gas and the noise is there. Is this bearing noise? Are these models prone to this? Also, has anyone changed the bearings on thiers before and do I need any special tools for this? Anyone with help or info would be greatly appreciated. Thanks!!!

 

Hard to "define" noise from reading a statement....LOL Best geuss would be the whine is either coming from the diff or transmission. You might put an audio/video on here and that may helps us determine the noise.....

 

I am not able to do this (get sound) as I am not at the home where I keep the ATV this week. Another person mentioned that it sounds like a bad middle drive gear shaft bearing. How hard are the bearings to change out? What soecial tools do I need?

 

I am not able to do this (get sound) as I am not at the home where I keep the ATV this week. Another person mentioned that it sounds like a bad middle drive gear shaft bearing. How hard are the bearings to change out? What special tools do I need?

 

Ok so here is the issue. This bearing is failed and completly torn apart. The outer race is stuck in the case, the inner race is stuck on the gear shaft. Any ideas on how I can remove both?

 

There are usually several ways to remove the race off of the shaft. Cut it off with a torch ( not recommended unless really good with a torch ), Cut it of with a die cutter ( still must be careful ), heat it to a cherry red ( the race ) and try to knock it off with a hammer. As far as the race stuck in the case, use a bearing puller if you can access one or....a Dremmel with a cutting wheel, or a hacksaw blade ( and this is slow ). There may be other...easier ideas but these are which I have used.

 

I could be wrong, but it looks like you have a bigger issue than a busted bearing....if I'm looking at this correctly, it appears as if the bearing housing is cracked in two places. Not to mention all the damage to the surface edge of the housing. Not sure how it all goes together, but those items seem to be harder to fix.

 

^^^^^Good eye...I looked again and noticed the cracks Yipes
...after you had mentioned it....

 

So I am going to have to change out the whole crank case now? Great.