2010 YZ450 Head Damage

You can probably reuse most of them, especially if you heat the case to 250 ℉ before removing them. The trouble is that you can spot a bad one, but there's no way to know how long before a good one goes bad. The left side main shaft bearing is the most prone to failure, so I wouldn't reuse it. If you decide to reuse the mains, be very critical in your inspection. I would call that case repairable, BTW.

You can probably reuse most of them, especially if you heat the case to 250 ℉ before removing them. The trouble is that you can spot a bad one, but there's no way to know how long before a good one goes bad. The left side main shaft bearing is the most prone to failure, so I wouldn't reuse it. If you decide to reuse the mains, be very critical in your inspection. I would call that case repairable, BTW.

Thanks for the suggestions.

I was able to split the case wednesday evening. I discovered the root cause of my problems is that 5th gear broke. One of the cogs/dogs on the side of the gear broke off, along with a good chunk of the root of that cog. When that chunk passed through my oil pump drive the deflection of the pump or the passing of the piece broke a portion of my right side cover too. Not an important part though.

Inspection of the bearings found that the left side main has slight irregularity to the rotation. It may be due to debris from the gear damage, but it isn't worth the risk. I feel the same about the rest of the bearings. They are cheap in comparison to the labor required to replace them later.

Out of curiosity I searched this forum for posts about broken transmission gears on the 2010 and there are several. I went to the KXF450 forum and I didn't find any posts about broken gears. Are broken gear problems unique to YZ's? My '04 suffered broken gears and then worn drive cogs causing gears to disengage. My '08 had problems with the drive cogs on the side too.

There aren't as many KXF's as YZF's, so I don't know if it's fair to use absolute numbers as a gauge, but broken gear boxes is one of the few consistent things that come up with the Yamahas. OTOH, of everyone I know personally who has one, I know of only one who has had gear trouble. I think it's something that depends a great deal on the rider. That doesn't necessarily say that you've done anything wrong, because some of that can be a result of using lots of power over rough ground and having the wheel bouncing around at full throttle. Tough on things.

There aren't as many KXF's as YZF's, so I don't know if it's fair to use absolute numbers as a gauge, but broken gear boxes is one of the few consistent things that come up with the Yamahas. OTOH, of everyone I know personally who has one, I know of only one who has had gear trouble. I think it's something that depends a great deal on the rider. That doesn't necessarily say that you've done anything wrong, because some of that can be a result of using lots of power over rough ground and having the wheel bouncing around at full throttle. Tough on things.

Agree. I weigh 215. My '04's gearbox broke at full throttle through some big whoops at Milestone. The '10 had to have broken during my ride at Cahuilla. It has a long uphill section where I may have used 5th gear when I was trying to pass Brett Metcalf... or at least keep him in sight a little longer. When I heard a noise from my engine it was on a sighting lap on Pala's national track. I didn't get out of third gear.

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