YZ450 oiling problems?

[Jon K.]

A buddy of mine has a YZ450 (actually it is a dreaded q u a d) pulled down in his shop, and the intake cam (and the cap and head) show scuffing. Bad enough that we don't want to run it anymore.

Looks like lack of oil.

This engine has been run hard, but properly maintained.

He is using some sort of high-dollar Bel-Ray. XP, EXP, EXT, or something like that.

Does the 450 have any tendencies toward losing oil to the top?

Where is the oil pick-up for this engine? This q u a d is used for circle track racing, and it occurs to me that if the oil pick-up is on the left, that might cause the pump to suck air as the oil gets pushed to the right side of the engine in the turn.

I'm hoping that some-one out there might have some insight into the m/c engine, as it is basically the same.

Jonny

 

[SFO]

Cam journal seizure is not uncommon.
Every head I have measured has come from Yamaha with under .001" clearance.
The service limit is .003" I believe.
Mike at EDCO

http://www.enginedynamics.com/

is doing a brisk business of repairing this journal on the yz-f and suggests using 5ftlbs for a torque value instead of the suggested amount.
He sets the clearance in the middle of the range at .0015" as well.
This is the only plain brg in the motor and requires respect.

 

[DEANSFASTWAY]

The oil pckup is rear the middle of the motor real low . Is there an oil tank ? is it real low in the frame ? A local racer( 426 motor)had some trouble one night when he cartwheeled his quad and the scavenge part of the pump went dry but he had the oil tank really low on the frame . Ive seen some Suzuki 400 cyl heads with really bad cam journals also .

 

[Jon K.]

Good info guys, I will call Mike, and glance at the tank.

Thanks;

Jonny

 

[yarbonwick]

Jon K what did you find that caused this? I just had a buddies 04' YZ450 do exactly this after having the valves checked by a untrust worthly bike shop.

 

[Jon K.]

Jon K what did you find that caused this? I just had a buddies 04' YZ450 do exactly this after having the valves checked by a untrust worthly bike shop.

I never really figured anything out, just changed some parts and haven't had any problems since.