How do these valves look?

[memphis2857]

I am not sure if you can tell by looking at the picture, but I am curious how much life these valves have left in them. Anyone have a picture of a worn out vs. a good valve?

[Qqqqqqqqqqqq]

shows signs of wear ... obviously

do they leak .. is the valve clearance stable or do you have to reshim often ... how many hours on them ??

https://www.thumpertalk.com/forum/showthread.php?t=1020337&highlight=worn+valves

[memphis2857]

I dont know anything about them. I bought the head used and was just wondering if I could get one riding season out of them.

[William1]

Might want to mention the bike they are from....

But not knowing that, they look worn. What were the clearances and shim sizes installed?

Did you check for leakage?

[phantomtracer]

The top looks good, normal carbon deposit for a head/ valve with a fare amount of mileage, I would say the valve guides are ok for the season. Go to an automotive store and buy lapping compound and a hand valve lapper tool (only a few buks).

If you can lap the valves and obtain a good seal it's probable good.

[memphis2857]

its a CRF450. The valves didnt leak, and compared to the valves that were in my old head these things look brand new. Not sure about the shims cause there wasnt any in it. I bought the head with intention of putting valves in it but this rebuild is costing way more than expected and I really need to cut some costs.

[FORMA MOTO]

Those are CRF450R valves, and they have already started to cup. If you shim them, and trial ride the bike, you might get 5-20 more hours out of them before you need to shim them again, and again. They will eventually break off from fatigue, as the Titanium coating is wearing off, and the seat and valves are being affected by the heat.

If you race the bike, you might not even 2 hours.

They are going to be toast soon.

You need to re-build the head.

[MX Tuner]

You shouldn't use lapping compound on any surface hardened titanium valves. When installing new valves in a used head, be sure to have someone who is qualified to recut the seats in the head to insure a nice symmetrical shape for the new valve to seal against, otherwise the valve life can be reduced greatly.

[Shawn_Mc]

MX Tuner is spot on.

You could lap a stainless valve and put it in there and forgo the valve job, but its not the "right" way to do it.

Some guys have had luck lapping the seats with the old Ti valve and then installing a new one. Still not the right way to do it though.

[phantomtracer]

You shouldn't use lapping compound on any surface hardened titanium valves. When installing new valves in a used head, be sure to have someone who is qualified to recut the seats in the head to insure a nice symmetrical shape for the new valve to seal against, otherwise the valve life can be reduced greatly.

Doooooo. Sorry I gave you bad info. Titanium valves no lapping.

You could try the old water test it might not be perfect but it's cheap.