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RiderDeAzul

Valve job

11 posts in this topic

So I took my head to a cycle shop to have new valve seals put in and they are now telling me I need 5 new valves and 1 valve bucket, so I guess my question here is how can you tell if the valves are shot, I think they are just trying to overcharge, but I don't want to accuse without any knowledge.

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First, you determine how far from new, the valves have receded in to the head.

Next, you remove the valves and inspect. You check for pitting on the valve contact area, uneven wear, cupping of the valve.

 

You have a race engine. Expect race engine expenses. Valves can last as little as 15 hours in a neglected bike to over 300 for those that take good care and do not beat on it. My last Yamaha went 216 hours and even then, the valves failed because the automatic cam chain tensioner went, bending a valve. The correct fix was to redo them all while it was apart along with fresh rings (piston too if showing signs of wear)

 

What made you think you just needed new seals? They rarely fail.

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First, you determine how far from new, the valves have receded in to the head.

Next, you remove the valves and inspect. You check for pitting on the valve contact area, uneven wear, cupping of the valve.

 

You have a race engine. Expect race engine expenses. Valves can last as little as 15 hours in a neglected bike to over 300 for those that take good care and do not beat on it. My last Yamaha went 216 hours and even then, the valves failed because the automatic cam chain tensioner went, bending a valve. The correct fix was to redo them all while it was apart along with fresh rings (piston too if showing signs of wear)

 

What made you think you just needed new seals? They rarely fail.

My cylinder had a big gouge in it, and I was replacing the piston and cylinder, and I was told by some friends that it would be best to just replace the valve seals while I had it torn apart, when I checked clearances, all but one of my valves was in spec, and the valve that was out of spec was only out by 0.01 should I just have them replace the seals and then take the valves out myself and inspect them?

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Depends.

Are you capable of determining the condition of the valves?

Do you know if they have ever been reshimmed?

If a shop is going to remove all the springs to replace the seals, it is an additional five minutes time for them to inspect the valves. If you have doubts, go to the shop and have them show you the problem spots on the valves.

 

 

From reading your various posts, it seems you bought a used and abused bike and are stuck righting another persons failures, all too common when a guy beats on a bike and then decides to unload it rather than fix it. I'd wager the valves were reshimmed just before you bought it to enable it to run. Sellers do that all the time, even advertising it was done because the uninformed see that and think it is a good thing. A good thing would be hearing the valves were just checked and have NEVER had to be reshimmed.

This sort of thing happens all the time, unfortunately.

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Depends.

Are you capable of determining the condition of the valves?

Do you know if they have ever been reshimmed?

If a shop is going to remove all the springs to replace the seals, it is an additional five minutes time for them to inspect the valves. If you have doubts, go to the shop and have them show you the problem spots on the valves.

 

 

From reading your various posts, it seems you bought a used and abused bike and are stuck righting another persons failures, all too common when a guy beats on a bike and then decides to unload it rather than fix it. I'd wager the valves were reshimmed just before you bought it to enable it to run. Sellers do that all the time, even advertising it was done because the uninformed see that and think it is a good thing. A good thing would be hearing the valves were just checked and have NEVER had to be reshimmed.

This sort of thing happens all the time, unfortunately.

Alright, I guess I'll just replace them then, I heard that titanium valves break more often than stainless steel valves, is this true? People also say that you see a loss in performance, is it actually noticeable? Thanks for your help, atleast now I know to stick to 2 strokes haha.

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Alright, I guess I'll just replace them then, I heard that titanium valves break more often than stainless steel valves, is this true? People also say that you see a loss in performance, is it actually noticeable? Thanks for your help, atleast now I know to stick to 2 strokes haha.

Not true. Ti valves weigh less and are higher performing. Installation/fitting requires greater skill. Stainless are a cheaper alternative. Ti, if proper care is taken, will last longer.

The valves do not beak, they wear. They wear because dirt gets into the engine because the bike is not properly serviced.

You would not notice a loss in performance with stainless.

Personally, I'd replace with OEM Ti valves, with the seats cut on a SERDI machine.

 

A 2S is only cheaper for the single rebuild. Rebuilds (as part of maintenance) are more often occurrence with a 2S. Over the long run, the costs average out except in cases of abject neglect, then a 4S can cost more.

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Not true. Ti valves weigh less and are higher performing. Installation/fitting requires greater skill. Stainless are a cheaper alternative. Ti, if proper care is taken, will last longer.

The valves do not beak, they wear. They wear because dirt gets into the engine because the bike is not properly serviced.

You would not notice a loss in performance with stainless.

Personally, I'd replace with OEM Ti valves, with the seats cut on a SERDI machine.

A 2S is only cheaper for the single rebuild. Rebuilds (as part of maintenance) are more often occurrence with a 2S. Over the long run, the costs average out except in cases of abject neglect, then a 4S can cost more.

Seeing as I just got the bike would you recommend replacing regardless of the wear?

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Well, if I were taking it all apart like you are, seeing the damage to the barrel, probably. All major wear items that can suffer from neglect would be questionable.

I'd also replace the cam chain and the cam chain tensioner (I'd get a manual one and do away with the automatic style)

 

Did the area where the cams live look clean or was it at all burnt looking?

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Well, if I were taking it all apart like you are, seeing the damage to the barrel, probably. All major wear items that can suffer from neglect would be questionable.

I'd also replace the cam chain and the cam chain tensioner (I'd get a manual one and do away with the automatic style)

 

Did the area where the cams live look clean or was it at all burnt looking?

They looked really clean, I was honestly surprised when they told me that I would need to replace the bucket and all 5 valves, my cam chain has no play in it, should I still replace it anyways? I'm trying not to go completely broke, but I want a bike that will run without blowing up...

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Basic

 

They looked really clean, I was honestly surprised when they told me that I would need to replace the bucket and all 5 valves, my cam chain has no play in it, should I still replace it anyways? I'm trying not to go completely broke, but I want a bike that will run without blowing up...

Basic rule, anytime you do a barrel or valve job, replace the cam chain. Automatic tensioners should be replaced every other cam chain. Older bike like that, the tensioner is always suspect. If you plan to keep the bike,  a manual one will give you 10X the life.

A cam chain is between $20 and $40, depending where you get it and a five minute install.

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Alright, which manual one should I buy? I usually buy my parts from rocky mountain but I don't see any on their site

Edited by RiderDeAzul

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