yzf bottom end

[james everett]

inspection cover came loose on 2007 yz450f while riding.son said he notice oil on boot and stoped riding.i changed oil and bike only had about a pint of oil in it.bike starts easily and has power but engine noise is louder. if i do a top end is there any way to check bottom end without splitting cases.thanks :oh :bang:

 

[Ol'89r]

Chances are if there is any damage to the engine it will be to the top end. When your engine runs low or dry of oil the top end is the first part that suffers damage. Usually the camshaft journals will seize and or the camshaft itself will gall. The cam runs directly on aluminum journals and is the first place to be starved for oil. Look for excessive wear marks or signs of excessive heat. Check the valve spring cups for wear. They can seize in their bores from lack of oil.

Remove your top end and inspect the cams and journals. While the head is off, grab the rod with your hand and try to move it up and down against the crank. If the rod bearing is bad you will feel some movement in the bearing. Rotate the crank. If it is smooth and quiet it should be ok. If you feel or hear a rumbling sound, your main bearings may be bad.

Measure your piston for wear and look for signs of heat on the wrist pin and small end of the rod and also the cylinder.

Your bottom end is set up with good quality ball bearings and will run a surprisingly long time with very little oil.

Good luck.

 

[james everett]

low oil

thanks for the info.have a good day thanks