2011 YZ 450 rebuild or not?

Just wondering. I have a 2011 YZ 450 F that has around 70 hours on it. I am almost 53, I ride well in the over 40 A class, and in the 45 and 50 classes, I am usually top dog. So I ride hard, but am no where near 450SX speed in my advanced age. I change the oil every ride (usually less than an hour time, or at least only one full tank anyhow) and use a Stainless steel oil filter. Used Devlac oil. I have never took the head cover off to check valves. Never sis it since I owned a 08 Honda 450. My 2009 and 2010 YZ's I traded in with 50 plus hours and they always started fine.So that's why I haven't checked them.

In the engine, what would you change if you were to keep the bike? I figure just the piston and rings and such, but really not sure. This is going to be a practice bike, as it is now, and sometimes a HS bike. I am looking for reliability was thinking of just another OEM piston, but what are your thoughts on other pistons? How about higher compression pistons ( I still want to use just pump gas)? timing chain? when does that need replaced? Cranks? I seldom use the clutch, as I never have to adjust it, but ride with my finger on it everywhere. I am going to repack the muffler again using the steel tube insert and fiber matting material from Moose Racing. I do that every 20 hours.

If I keep it, I will also do a full suspension rebuild with new bushings and seals. I haven't changed the oil in the shock or forks for 24 hours. In the past I have used KYB factory oil.

I'd check the valves, odds are they haven't moved yet. As for the piston, I'd do one around 100hrs, and might as well do a cam chain at the same time. I'd also stick with OEM piston, your not going to get much if any more hp from an aftermarket, and most are single ring, so the rings will wear out faster. If you want reliability, OEM is the way to go.

Does anybody know how to check the head?

Does anybody know how to check the head?

yea by checking valve clearances, if they haven't moved the valves are ok. if you wanna go crazy you can check the cam journals with plasti gauge.

Yamaha's are good for 200+ hours before you need to think about rebuilding the motor.


Suspension rebuild is more important.

Yamaha's are good for 200+ hours before you need to think about rebuilding the motor.


Suspension rebuild is more important.

That's what i heard too. my 11 had ~110 hours, basic maintenance done on a regular basis. Crank play was "estimated" during last top end , no issues. no suspicious debris in oil and filter after each oil change (5 hours). 


Then 30 min into a session I heard a strange noise and pulled over right away.

Crank is gone, thankfully not fully gone. so there was some damage control. still some $$$ since some metal got between cylinder/piston 


I would not go more than 100 hours before a bottom end rebuild, regardless of reliability reputation or absence of warning signs

these are high performance engine and need some attention.

I am not arguing that a lot of YZF or other brands have 200+ hours, just sharing my experience

Has any one done valves yet? I was told the make sure the valves were were completely up and pour fluid ( diesel fuel) in the ports and to check for leaks. I found my intake valve are leaking. Not sure what valve to get and if they even need replaced?

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now