Hi All!
Doing some maintenance on my 23 yz450f. I have the head taken off and I am unsure about this wear on the cams where they meet the head alloy journels. The head to me looks good and normal but the cams have worn part of the coating off but only about half or so on one end. Like one side looks like a brand new cam that’s never been ran, the other side doesn’t look necessarily bad at all but weird how it’s on one end, opposite side of the timing chain. All very smooth and nothing that I can feel with my fingernails at all.
Little backstory- At 109 hours it just recently started smoking a tiny bit when the bike is on the stand and you give it a throttle blip it would puff a light smoke on decel. I suspect valve seals but am doing that along with OEM base and head gasket and new piston rings (even though the cylinder looks damn good for the hours and I did a piston and rings 10 hours ago)
Please let me know what you would do if this was yours. Appreciate the feedback!
Could be fixed Doesn;t look that bad Qhat does bridge look like Post pic
Nothing looks bad or unusual to me for 110 hours.
With what ita doing when you blip it I would suspect the valve seals as well. When you give it a quick blip and it has that sudden jump in rpm on the stand or sitting in netural that can happen. If everything looks good and cams rotate cleanly while the chain is off and the caps torque down I think you will be fine.
Did you measure the bore to check for wear. Honestly I doubt thats the issue at 110 hours unless your hard on motors. But id expect to see more wear in ur photos if you did.
Appreciate the feedback! That is correct both cams do rotate freely and smoothly with out the timing chain and caps torqued to spec. I did not measure the bore, though the cylinder crosshatch still looks close to how a new one would look
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