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Do you think these titanium valves are dead ?

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Here are the exhaust valves and the intake valve (biggest) :

2valves.jpg

exhaustd.jpg

intakew.jpg

Here are the seat valves (berylium copper) :

headmna.jpg

Do you think the valves are ok or not ?

What about seats valves ?

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I hate to offer an opinion here as I am not race engine oriented. But I'd say they look just fine. The intake looks perfect. The exhaust just a hint of wear. I know opinions on refacing Ti valves vary but a local shop here in WA does it with good results. If it can be done and still have acceptable margins, why not.

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hard to say with only pics.

if reground you will need to get them recoated with dlc or similar i would think.

looks like the coating (gold color)is still on the valves but????

can you confirm?

seats look ok from here anyway.

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They have done betwwen 60 and 120 hours. The coating is still on the valves but the problem is that valves are leaking when I put gazoline in the exhaust and intake pipe (a lot for intake valves and a little for exhaust valve).

I am not sure reground and then recoat quite old valves is a good idea for my wallet (if finally the valves need changing in a couple of yours...).

But I suppose leaking is a real sign of failure that won't go ok alone, isn't it ?

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They have done betwwen 60 and 120 hours. The coating is still on the valves but the problem is that valves are leaking when I put gazoline in the exhaust and intake pipe (a lot for intake valves and a little for exhaust valve).

I am not sure reground and then recoat quite old valves is a good idea for my wallet (if finally the valves need changing in a couple of yours...).

But I suppose leaking is a real sign of failure that won't go ok alone, isn't it ?

Leaking = FIX. :busted:

Valves and seats reconditioned or replaced :busted: Pretty much as simple as that.

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They have done betwwen 60 and 120 hours. The coating is still on the valves but the problem is that valves are leaking when I put gazoline in the exhaust and intake pipe (a lot for intake valves and a little for exhaust valve).

I am not sure reground and then recoat quite old valves is a good idea for my wallet (if finally the valves need changing in a couple of yours...).

But I suppose leaking is a real sign of failure that won't go ok alone, isn't it ?

Just out of curiosity...

How much are they leaking? Like, is gas actually dripping straight through, or is there just a damp spot after an hour?

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One "spot of rain" each second for exhaust valves, about 5 "spots of rain" each second for intake valves.

On this video you can see the middle cylinder valve which is leaking a little more than my intake valve. The right cylinder valve is leaking a little less than my exhaust valve.

http://www.youtube.com/watch?v=n7YXgJPmV5M

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They sure don't look like they would leak at all. Is that will springs? or just set against the seats. Try cleaning the valves and seat with a non-abrasive cleaner and fully assemble and try the leak test again.

Also use some "blueing" to determine contact. Maybe the valves are warped or bent that we can't see in the pictures.

Why are the valves suspect? routine maintenance, running problem, over rev, low compression, poor leak-down test, hours of use?

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Yes the leak test was done with springs. What do you mean by "non abrasive cleaner". A piece of cloth with fuel for example ? For blueing, can I use grease ?

I have just bought the full head. The motor was broken on the track. Because of that and because I know the head has run at least 60 hours (probably twice more), I prefer to be sure that there is no problem before I close the engine.

I wonder if I won't hurt too quicly seats and guides (they are berylium-copper) if I go to steel valves.

Edited by chris95

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Non abrasive cleaner - scrub with a mesh cloth that odes not contain abrasive. Around here that would be white Scotchbrite that only contains talc or any household cleaning pad safe to use on Teflon coated cooking ware. And fuel or other solvent or even a strong detergent cleaner.

OK, so you don't know very much about this head. The valves could have been damaged by a engine failure. I don't see evidence of burning or carbon deposits from being run with leaking valves. You can chuck up the valves and spin with a dial indicator look for run-out (bending). If bent, they need replacement.

Grease is not a good way to determine contact. An automotive shop with have blueing (Prusson Blue). It is used various places, often with gears to determine contact.

It sounds like this head has had some careful attention to valves, seats, and guides. If possible contact the shop that did the original work for replacement parts and service. I don't see a problem with steel valves and beryilum-copper seats and guides but I would check with the shop that did the work. The other thing is it is kind of a waste to only go half way. You should restore the head to its fully race preped condition or just go buy a standard head if you don't need the special race features.

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My CRF250 looked similar to that. Not as many spots but still you could see they weren't perfect. I used a non scratch pad and carb cleaner to clean them up and reassembled with fresh springs and new piston. Broke it in for an hour or so and pulled it down for clearance and leak down checks. Clearance was spot on and it had 7% leakage which as far as I know is pretty dang good. You could try that route if you really wanted but if you can swing it a proper rebuild is probably the best bet.

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Clearance was spot on and it had 7% leakage which as far as I know is pretty dang good. You could try that route if you really wanted but if you can swing it a proper rebuild is probably the best bet.

5-7% or under is what I look for on a new engines I build, above that and something is not as good as it should be.

On a used performance engine, above 10% and it's time to pull it down.

Other people’s Street engines up to 25% if the owner wants to let it go that far is acceptable (some will say 30%, to each his own)

Edited by E.Marquez

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