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My first valve problem......a few questions.

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03 CRF450R. Bought used last season, valves were shimmed before it was sold. I put maybe 20 hours on it last year with no problems. Vavles were in spec at the end of the year. I rebuilt the motor this year, new piston and rings, new valve seals and springs. I installed an hour meter at time of rebuild. At 12 hours, I checked the valves and all were perfect. Tonight I checked again, now at 25 hours and the left side Intake valve is at zero, no gap. What would cause one to go that much that fast? Can I put a shim that is .006 smaller than the shim in there and be good for the remaining season? Maybe another 7-10 hours tops. From what I've read on here, once they start, they go fast. Is that true? Am I risking bigger problems be not fixing it right at this time?

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Yeah man once they go its pointless to not get a set of Stainless steel valves.. I have an 03 myself and i put well over 100 hours on the thing.. And my valves finally went out.. I went and got some OEM valves and they were gone with about 20 hours of riding time.

So do yourself a favor and either get the Ferrea valves and springs from RHC or the Kibblewhite replacement valves and springs. I just put the Ferrea stuff in mine tonight and am going riding tomorrow. If the track is open. Hope that helped!

Otherwise.. do a search! Youll find all the info you need on this subject!

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Agree with Black450R ... once your valves become this far out of tolerance, you'll need to replace them soon.

As for reshimming with a shim that's .006 smaller, this will be a good starting point, but no guarantee that you valves will be back in tolerance ... you could very well be at a negative tolerance and just not know it at this point. Install a shim that's .006 smaller, and re-check ... you may have to re-shim once more to get back to precise tolerance.

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Go SS!!! But, for what causes the valves to go south in the first place. They have a nitride coating over the titanium. If the coating becomes compromised (usually from dust getting by the air filter) the valves start to eat away. You may have had a 'micro' leak somewhere in the intake. I had the same problem as you and my bike is still torn down waiting for my KW valves (tomorrow). I diodn't want to risk a catastrophic failure.

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Wouldnt dust or dirt affect both valves? So I would be taking a risk to reshim at this time?

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Long reply-

I do not know why the exhaust valves aren't as susceptable except that perhaps during the combustion process it (dirt) gets broken down into micron size pieces. I'd venture that your exhaust valves are in spec. Me, if you don't have to add too BIG of a shim to bring it to spec, go for it. But, if it's at the bottom range of shimability I wouldn't risk it. That thing let's go while you're airing out a 60' jump bad things could happen. Even if not on a jump, a $315 (valves and spring kit from Lytle Racing Group on ebay) new SS valve kit turns into a much more expensive repair.

If it's super important for you to ride this weekend borrow a bike. Otherwise, wait to get the KW's or put some OEM's for another 15 hours. You can weigh the optins and make a decision. I had a similar situation 2 nights ago while cutting some metal. Safety glasses were in the house I almost convinced myself I'd be careful and get the glasses later. Then I thought what's 30 seconds vs. a lifetime of vision issues (blindness). The valve thing to me is the same decision. Wait a weekend if you have to and catch up on other stuff around the homestead.

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Long reply-

I do not know why the exhaust valves aren't as susceptable except that perhaps during the combustion process it (dirt) gets broken down into micron size pieces. I'd venture that your exhaust valves are in spec. Me, if you don't have to add too BIG of a shim to bring it to spec, go for it. But, if it's at the bottom range of shimability I wouldn't risk it. That thing let's go while you're airing out a 60' jump bad things could happen. Even if not on a jump, a $315 (valves and spring kit from Lytle Racing Group on ebay) new SS valve kit turns into a much more expensive repair.

If it's super important for you to ride this weekend borrow a bike. Otherwise, wait to get the KW's or put some OEM's for another 15 hours. You can weigh the optins and make a decision. I had a similar situation 2 nights ago while cutting some metal. Safety glasses were in the house I almost convinced myself I'd be careful and get the glasses later. Then I thought what's 30 seconds vs. a lifetime of vision issues (blindness). The valve thing to me is the same decision. Wait a weekend if you have to and catch up on other stuff around the homestead.

Good advice. When you do replace the valves with SS stuff go ahead and inspect the entire intake system for leaks, dry rot or anything else that isn't supposed to be there. Valves in the CRF's have two mortal enemies: one is dust getting past cheap air filters; best to stick with stock or UNI as all others are junk and two is the high end of the RPM range. If you peg her often the OEM valves can't take it and this situation combined with even a fine amount of dust is what really kills the valves. Most guys whose re-valve jobs that only last 10-20 hrs now this all to well. The SS type valves can take a beating far beyond what the OEM stuff can. As far as the exhaust valves go they are not in the direct line of fire of dust like the intakes are. A lot of the dust is atomized at combustion and instead of eating the valves on the way out of the motor it contributes more to build up and carbob depositing. :banghead:

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I have an 03 as well with abhout 120 hours on it and the intake valves finally went. I found out that Honda is now making their own SS valves for the 450, and a spring for it. So my mechanic recommended that I put the Honda OEM SS valve springs retainerss etc... While I'm at it I am throwing a new 04 Piston and rings in it. Shouyld be a new bike. Has anyone else heard of the Honda OEM SS valves?

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That's the word I was looking for...Atomized. I put on a new Ready Filter every 2 hours. I don't think these are bad! In fact, I feel they're AWESOME!!! But, I ride my biek hard and the OEM valves can't tkae it. Thanks for your reply gchprime.

Thanks,

Adam

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Quote : " best to stick with stock or UNI as all others are junk ".

Oh, I don't think Twin Airs are "junk". Team Honda uses them exclusively in their Baja bikes along with the TwinAir cage, as a matter of fact.They take quite the beating down there.

I have never seen a speck get past my TwinAirs in the intake tract or carb , and I've used them for years , in my KTM's,too. I use BelRay filter oil because I started using it at the same time , although I'm sure there's a lot of good filter oils out there. Doug

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I just called my Honda dealer and they know nothing of OEM SS valves. But, they may be so new that they don't know about them.

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In my experience, racing MX, Twin Air in my CRF450 using K&N filter oil never did as good a job as the stocker or the UNI. BTW, steer way clear of the K&N paper filters unless you never ride where it is dusty! They flow good but don't catch much.

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Long reply-

I do not know why the exhaust valves aren't as susceptable except that perhaps during the combustion process it (dirt) gets broken down into micron size pieces. I'd venture that your exhaust valves are in spec. Me, if you don't have to add too BIG of a shim to bring it to spec, go for it. But, if it's at the bottom range of shimability I wouldn't risk it. That thing let's go while you're airing out a 60' jump bad things could happen. Even if not on a jump, a $315 (valves and spring kit from Lytle Racing Group on ebay) new SS valve kit turns into a much more expensive repair.

If it's super important for you to ride this weekend borrow a bike. Otherwise, wait to get the KW's or put some OEM's for another 15 hours. You can weigh the optins and make a decision. I had a similar situation 2 nights ago while cutting some metal. Safety glasses were in the house I almost convinced myself I'd be careful and get the glasses later. Then I thought what's 30 seconds vs. a lifetime of vision issues (blindness). The valve thing to me is the same decision. Wait a weekend if you have to and catch up on other stuff around the homestead.

Alright, I'm going to replace the Intake Valves with OEM ones for now. Bike has close to 100 hours on it with the stock ones, I dont see the need to spend the money on SS. Is it likely the seats are going to need to be cut?

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Probably not. Actually SS valves are less expensive than OEM. It's the spring kit that costs the $. At Lytle Racing's ebay store the exhaust and intake KW SS valves are $29 per and the spring kit is $188.

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I replaced mine with a RHC kit. WOrks great.

THe local dealer said many people are replacing the stock titaniums with the 450 quad steel valves instead.

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So, the engine they put in teh quad has SS valves. Is that what I'm reading? I'm putting a post on the TRX450R forum.

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So, the engine they put in teh quad has SS valves. Is that what I'm reading?

Yes, this is a true indication that Honda knows the Ti stuff sucks. The quads weigh more and the guys who ride the quads in general weigh more too. To get

Yamaha matching performance they made a few changes. In fact, the motor is a little different too. Next time you are at the dealer give it a look. The only thing that looks the same is from the cylinder up. Since the YZ450F motorcycle is not as good as the CRF450R I guess Honda figured they could hold off it. But since the Yamaha quad is better they had to put forth more effort to make the TRX450 more competitive. :banghead:

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Are they interchangeable with an '03 CRF450, 36mm intake & 31 exhaust? I already have Kibblewhites coming but this is interesting?

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good info guys but back to my question, Am I going to have to grind the valve seats now that one of my valves is that for out of spec?

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Re: My first valve problem......a few questions.

Probably not. Actually SS valves are less expensive than OEM. It's the spring kit that costs the $. At Lytle Racing's ebay store the exhaust and intake KW SS valves are $29 per and the spring kit is $188.

Proabably not.

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