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New OEM titanium valve - seat grinding / lapping

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I know this subject has been pretty well covered throughout the forums but there are a couple of potential make or break details that I cannot find a definitive answer for. Mainly on the subject of valve seat preparation and lapping.

For a little bit of background, I have an '07 CRF450r with approximately 40 hours on it (Vet B weekend rider). The intake valve on the left has gotten tight on me twice so I figure it's probably on borrowed time right now. The last time the shim was a pretty big jump smaller to get it in spec. Not going to touch the exhaust valves or piston since everything else looks really good. I'm planning on going a little off the beaten path here and throwing in new OEM titanium valves and just touching up the seats. If I can get another 40 hours out of $100 set of valves I'll be happy to do it again whenever the need should arise.

A friend of mine who works on performance car engines (he has a race car) says no problem to "touch" the seats for me to clean them up and get it ready for new valves. The tool he's using is a hand-held device that centers itself in the valve guide and applies an abrasive device to the seat surface to grind it smooth. Does this sound right?

Normally then you would lap the new valves in after regrinding the seats. If you can't lap the titanium valves, what would need to be done in it's place or do you simply not do anything? Would it makes sense to buy a sacrificial valve (cheap steel one) to use only for lapping the seats or is that not necessary?

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You do not lap the titanium valves at all, if you do that the coating wears off and the valve will live a very short life.

Just touch up the valve seats and you're good to go.

You will want to replace both intakes and also throw in a new set of springs.

Your valve lost clearance either because the spring couldn't control the valve at high RPM and let the valve float, or you sucked some dirt into the engine and the coating wore of the valve.

At any rate, I woudln't even go OEM. You might be doing another valve job down the road anyway. Since you're going to have the bike apart, you might as well throw some stainless intake valves and springs in there and be done with it. You won't have to worry about them again.

I have stainless valves in both of my CRFs. I would suggest the stainless intake valve and spring kit from Faction MX. You can pick it up for $150.

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I just read about a new tool that goes in to your seat and guide machine they are a driver with a 45 degree diamond lap to finish your seating angle to a very concentric and smooth finish .the serdi tooling may be state of the art and i use both stones and serdi but the serdi is a form tool and no matter how carfule you are with the machine its still tearing the metal i always hit the 45 with a stone when using the coated titanium valves im looking into purchasing the diamond laps it cant hurt.but stones are a good way to finish off the seat .

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I have been waiting to ask this question and this seems a good a spot as any...

I don't need to do this, yet, but if one buys a brand new OEM head and a brand new set of OEM (coated) valves, can the head be assembled, as-is, or does some valve-to-seat matching still need to take place? I guess it depends on the tolerances out of the factory...

Ed

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I don't need to do this, yet, but if one buys a brand new OEM head and a brand new set of OEM (coated) valves, can the head be assembled, as-is...

That's what they do at the Honda factory.

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I have been waiting to ask this question and this seems a good a spot as any...

I don't need to do this, yet, but if one buys a brand new OEM head and a brand new set of OEM (coated) valves, can the head be assembled, as-is, or does some valve-to-seat matching still need to take place? I guess it depends on the tolerances out of the factory...

Ed

I've done this with no problems. Like camp p said this is probably how a new bike is assembled at the honda factory.

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I just read about a new tool that goes in to your seat and guide machine they are a driver with a 45 degree diamond lap to finish your seating angle to a very concentric and smooth finish .the serdi tooling may be state of the art and i use both stones and serdi but the serdi is a form tool and no matter how carfule you are with the machine its still tearing the metal i always hit the 45 with a stone when using the coated titanium valves im looking into purchasing the diamond laps it cant hurt.but stones are a good way to finish off the seat .

sounds cool, wonder what these run, I'll wait to see how you like it first, hehe. I'll stick to the contour BB, and stones for now.

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Just do it right the first time you have to pull the head anyway just do all four, send your head to mxtime he does great work and is very resonable in price. I did our 06 250r complete with piston & rings for under 300. I was a little reluctant to send my head off but the turn around time was only about 5-6 days, I highly recomend this place let a proffesional do the valve cut..

http://www.mxtime.com/Valve%20Seat%20Cutting.htm

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At the end of the season I will be sending my head from my 06 450 to either AgentSmith or Ron Hamp. What can I expect for a total price for rebuilding it??? Just trying to get a basic idea for what I am going to spend so I can budget for the winter.

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Whats the process for fitting stainless valves..

Do you need to replace the valve seats ? etc ?? machining ?

Thanks

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First off, thanks for all the good info from those of you who responded.

Just to let you know, here is what I ended up doing: First off, I borrowed some tools to do the valve work myself but did not have the pilots down to the 5mm valve stem size on these. Ended up taking the head to a local guy who does some performance work on bikes and ATVs. Although not specifically specializing in the CRF250 or 450 "R" models, he did seem to know what he was talking about with the SS vs. Ti valves and all and has some good references. He and a helper took a close look at the valve seats and said there was no need to touch them. He said the only time he would do that is if they weren't sealing or if they were pitted or something like that. Also, he would lap them a little with fine compound even with the Ti valves.

I took the head home and installed new OEM Ti valves and seals but reused all the other original internals. Did not lap them. With the valves in the head, I checked for leaks by spraying starting fluid in the intake ports enough to where fluid pooled inside behind the valves. The inside of the combustion chamber stayed dry.

With this, I reassembled the cylinder and head of the engine and shimmed the valves. I was surprised to find that it took the same shims that originally were installed when I bought it but I guess that makes sense if there is no wear on the head. I changed out the factory shims since I decided to shim them about .001 tighter than that with the thought being maybe with less clearance, they are going to be under a little less stress. That stills keep it within tolerable limits by the manual since it specifies +/- .001".

I have done three ride days on it so far consisting of hot practice days (yesterday it was 93 and humid) at a pretty fast MX track (Tomahawk MX). I've kept a really clean filter on it and I think this week I will check the clearances to see if anything has changed. I will say the bike starts, idles, and runs perfect. I really don't see how it could run better.

I plan on adding an hour meter just to see how much time I get out of them and keeping a closer eye of the air filter which I do neglect from time to time.

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First of all you should've had them touch up your seats because now your new valve is not going to last and secondly you definitly needed to replace your springs, but whatever it's your motor.

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First off, thanks for all the good info from those of you who responded.

Just to let you know, here is what I ended up doing: First off, I borrowed some tools to do the valve work myself but did not have the pilots down to the 5mm valve stem size on these. Ended up taking the head to a local guy who does some performance work on bikes and ATVs. Although not specifically specializing in the CRF250 or 450 "R" models, he did seem to know what he was talking about with the SS vs. Ti valves and all and has some good references. He and a helper took a close look at the valve seats and said there was no need to touch them. He said the only time he would do that is if they weren't sealing or if they were pitted or something like that. Also, he would lap them a little with fine compound even with the Ti valves.

I took the head home and installed new OEM Ti valves and seals but reused all the other original internals. Did not lap them. With the valves in the head, I checked for leaks by spraying starting fluid in the intake ports enough to where fluid pooled inside behind the valves. The inside of the combustion chamber stayed dry.

With this, I reassembled the cylinder and head of the engine and shimmed the valves. I was surprised to find that it took the same shims that originally were installed when I bought it but I guess that makes sense if there is no wear on the head. I changed out the factory shims since I decided to shim them about .001 tighter than that with the thought being maybe with less clearance, they are going to be under a little less stress. That stills keep it within tolerable limits by the manual since it specifies +/- .001".

I have done three ride days on it so far consisting of hot practice days (yesterday it was 93 and humid) at a pretty fast MX track (Tomahawk MX). I've kept a really clean filter on it and I think this week I will check the clearances to see if anything has changed. I will say the bike starts, idles, and runs perfect. I really don't see how it could run better.

I plan on adding an hour meter just to see how much time I get out of them and keeping a closer eye of the air filter which I do neglect from time to time.

:excuseme::lol::excuseme:

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Also, he would lap them a little with fine compound even with the Ti valves.

I can see lapping the seat with a sacrificial valve IE steel or Stainless one if the seat was cut with a cutter tool instead of a stone, but lapping the Ti Valve is the kiss of death for it. The lapping compound will eat the coating for lunch and its not very thick to start with. The Ti is relatively soft compared to steel, thats why it needs the coating in the first place.

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I know this subject has been pretty well covered throughout the forums but there are a couple of potential make or break details that I cannot find a definitive answer for. Mainly on the subject of valve seat preparation and lapping.

For a little bit of background, I have an '07 CRF450r with approximately 40 hours on it (Vet B weekend rider). The intake valve on the left has gotten tight on me twice so I figure it's probably on borrowed time right now. The last time the shim was a pretty big jump smaller to get it in spec. Not going to touch the exhaust valves or piston since everything else looks really good. I'm planning on going a little off the beaten path here and throwing in new OEM titanium valves and just touching up the seats. If I can get another 40 hours out of $100 set of valves I'll be happy to do it again whenever the need should arise.

A friend of mine who works on performance car engines (he has a race car) says no problem to "touch" the seats for me to clean them up and get it ready for new valves. The tool he's using is a hand-held device that centers itself in the valve guide and applies an abrasive device to the seat surface to grind it smooth. Does this sound right?

Normally then you would lap the new valves in after regrinding the seats. If you can't lap the titanium valves, what would need to be done in it's place or do you simply not do anything? Would it makes sense to buy a sacrificial valve (cheap steel one) to use only for lapping the seats or is that not necessary?

what is the name of the tools ?

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First of all, 40 hours is way too low.  You should get at least 200 hours from your Ti valves.  Carefully inspect your air filter for dirt on the inside and brown residue around the intake.  Use a clean paper towel for this.  Granted Ti valves have their weakness in that when the coating wears off (my estimate is .005 in or 200 microns, the valve is shot and you will adjust it very frequently).  What kills valves is dirt so pay attention to this first.  If your valves don't leak gasoline or starting fluid after installation, you are good to go.  Don't lap.  If they leak, you need to dress the seats.  This is a bit trickier and should be done by a machine shop unless the wear is very slight and a hand dresser may work.  The higher forces associated with steel valves from the springs and inertia at high rpm's is a tradeoff.  You could see cam or lifter wear due to this.  If you are going to use high rpm frequently then the Ti valves are probably smart but for trail riding the SS valves have reportedly worked fine.

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