2005 RMZ 450 camshafts seizing in head

[sharky243]

A friend brought me his 2005 RMZ 450 that he recently purchased from a used bike dealer. He asked me to check it over to see if there were any problems or if it needed anything for the season. The bike is very clean, it looks well taken care of. I removed the valve cover to check the valve clearances and found it needed to be re-shimmed, no big deal. When I removed the camshaft caps, I found the journals were damaged from either lack of oil or lack of clearance for proper lubrication. I've told my friend that the head was damaged and would need to be replaced. I have semi-repaired the origonal head so i can put it back together to see if the oil pump is supplying oil to the head. Has there been any known issues with camshafts seizing on the RMZ 450's ? I know the RMZ 250's had issues in the 04'-05' years but not sure if the 450's had issues as well. Any info would be greatly appreciated. Thanks !!!

 

[Mophuka]

I haven't heard anything like that. I also have an 05. The stock piston and rings are not the best in the world. my bike was less than a year old and would burn oil like no other. My buddy liked to call it a 3stroke. Maybe it needed new rings and they just kept riding it and ran low on oil.. I could definately see that happening. I went with a different model number oem piston and rings and they seem to work much better.

 

[Ol'89r]

Sharky.

Not that familiar with the RMZ's but, on the Yamaha heads, they will do that if the caps are torqued too tight.

 

[Rich Rohrich]

The RMZs have the same issue as the Yamahas with incorrect torque and tightening sequence causing cam bearing issues. As SFO so eloquently put it:

It's the only plain bearing in the engine and it deserves respect.

 

[TRexRacing]

Technically it's a parent metal bearing.