YZ450F bearings

Hi guys,

I have a 2008 YZ450F and plan on doing some bearing maintenance this w/e after noticing a few things last weekend.

1. Front wheel bearing has a bit of play in it, plan to replace these (I know how to do this). Does anyone have the spec's on these front wheel bearings / seals? Bike shops are a rip off when it comes to selling these in aus.

2. Rear wheel bearing has no play but the seals are leaking. I take the bike out for some bush trail riding twice a month, is it worth just letting this go until the bearing inevitably corrodes? I plan to replace it as soon as their is any movement in the side ways movement rear wheel. Will this have any consequences if closely monitored? Specs on these bearings would be appreciated as well!

3. The bike stem is in good shape, turns smoothly. I have notice some oil leaking out of the stem occasionally. Does anyone have any good videos or instructions on how to rectify this? Why would this be seeping out oil from the top?

Replace the wheel bearings with a good quality OEM item. I would replace them sooner than later, the longer you leave it the more likelyhood of damage being caused to the hub housings.

Bearings are cheap, just replace them. Any play = failed/worn bearing. I use pivot works personally but OEM is not a bad way to go.

Replace the wheel bearings with a good quality OEM item. I would replace them sooner than later, the longer you leave it the more likelyhood of damage being caused to the hub housings.
Bearings are cheap, just replace them. Any play = failed/worn bearing. I use pivot works personally but OEM is not a bad way to go.

They're not that cheap in australia, front wheel bearing + seals are about $50... that's why I'm thinking about letting the rear one go until there's play evident.

Possibly fuel from the vent hose that goes down the center of the steering stem. Is it showing up on your front fender?

Jimmie

Good point, I doubt it though, I never saw anything on the front fender. It's coming directly out of the steering stem nut. Just a little bit every so often which I wipe away with a rag.

They're not that cheap in australia, front wheel bearing + seals are about $50... that's why I'm thinking about letting the rear one go until there's play evident....

Fair enough.....but they are still cheaper than a hub.

didn't notice where you were at. FWIW I never get play out of mine but they sieze up on me from time to time, I'll usually notice a torn seal on the bearing or some rust present.

Most of the wheel bearings use a flexible seal to keep the grease in on the bearing it self not the water dust seal. This seal can be removed and replaced with something like a dental pick you can go as far as to knock out your bearings ( carefully with heating the hubs) remove the seals clean the bearing, repack, put the shields back and reinstall. When you clean out all the old grease and spin the bearing it will feel pretty rough but if it's not to loose pack it and run it. If you don't want to remove the bearings from the hub you can just pick out the shield clean out the bearing with brake clean pack in some grease and get by. Even when you get new bearings it's a good thing to check under the shields to see if there is enough grease in there to start. If your bearings have full metal shields ( rare on Japanese bikes) you can't do this

Keep in mind that motorcycle wheel bearings are cartridge ball bearings that bear loads only perpendicular to the axis of the supported shaft (the hub). They are also not adjusted or preloaded axially for clearance as are typical bicycle wheel bearings. Since a brand new bearing will have up to around .001" clearance in it, this will show up as an ability to rock the front wheel side to side on the axle. The top of the tire is 3-4 times as far from either bearing as they are from each other, and as you rock it, you are seeing the total clearance in both bearings exaggerated by that extra length.

You'll see some wiggle in brand new bearings.

Bearing info for '97-up front wheels, and '99-'08 rear wheels:

Front - 6904-2RS - 20mm ID x 37mm OD x 9mm

Right Rear - 60/22-2RS - 22mm ID x 44mm OD x 12mm

Left Rear - 62/22-2RS - 22mm ID x 50mm OD x 14mm

Being a bit of a cheap SOB in a rainy part of the world, I get the cheapest $5 bearings I can find. They seem to hold up as well as the expensive ones -- the mud is going to get them anyway. I definitely pry off the seals and pack them with BelRay waterproof grease. Helps a little.

I seriously doubt that a little bearing wear is going to cause hub damage. Seriously, what could some side to side movement do the ruin a hub? From what I can tell, all it's going to do is maybe cause the rotors to rub on the brakes a bit more than usual and perhaps add some rolling resistance -- definitely not a big deal if you're on bike with a motor...

Thanks Grey, having the sizes handy for pre-order is so much easier than knocking the bearings out , getting the local bearing/fastener shop to size and order them followed by missing the next weeks race due to items being on back order.

Muchious Gratious.

Yes, $25 for both wheels from the local guy is so much cheaper than $50/wheel for Yam parts or 90/wheel for Honda.

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