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450Rich

2007 zyf450 valves

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Hi i have a 2007 yzf 450 that i have riddin for two seasons now.

i was chekin my valve clearance an my intakes are 11-12 mm in spec and exhasts are26-25 it seem weard that they don't need lots of adgustment.

should i re shim exhast or ride it more I am new to shiming and any help or opioin would help thanks

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i think if that you are within spec it should be fine. Why would you have to re shim? I'm pretty sure that shims dont wear out. Look in your manual at valve clearence specs, and adjust them what your specs are. I know my 06 YZ450f Is between.010-.015mm intake and .020-.025mm exaust. Pretty sure?

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... it seem weard that they don't need lots of adgustment.

You'll get used to it.

I had an '03 for 4 years that never once needed a valve adjustment.

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That is what I like to hear when I think about getting a YZ.

Why is that? Is the Ti they use a different grade? Is it the coating? Is it the seats or spring pressure? As a CRF guy probably going to become a YZ guy I would like to know the reason if there is a concrete one.

As an ex mountain bike racer I know there are lots of grades of Ti, and then different qualities of each. If I remember the MIL spec 3Al/2.5V tubing cost so much because it had to be x-rayed to inspect for imperfections every so often and that upped the cost tons (Merlin frames). Then they had Russian grade industrial for much cheaper (I had Ti bar ends made from that stuff)

Ti often is misrepresented as being a wonder metal that could do everything

and had all the properties you could ever want. In my CRF it was a 60 hour replacemment valve that I now keep at work on my shelf as a cool showpiece.

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That is what I like to hear when I think about getting a YZ.

Why is that? Is the Ti they use a different grade? Is it the coating? Is it the seats or spring pressure? As a CRF guy probably going to become a YZ guy I would like to know the reason if there is a concrete one.

I'm not absolutely certain, but I know that it isn't a secret in the industry. It's simply the right materials in combination with each other, and a good design executed properly.

A bad match up of seat material with the valves caused Honda quite a bit of their trouble in the past is all I can say for certain. But you are correct on two points:

> Titanium is a lot of great things, but it can't be made hard enough to hold up as a valve face without sacrificing strength, so the quality of the hard coating and it's application is extremely important.

> There is more than one kind of Ti alloy, and the tougher the base material is, the better the coatings will be supported.

Proper finish of the seats, and good valve guides also add into the longevity.

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I'm not absolutely certain, but I know that it isn't a secret in the industry. It's simply the right materials in combination with each other, and a good design executed properly.

A bad match up of seat material with the valves caused Honda quite a bit of their trouble in the past is all I can say for certain. But you are correct on two points:

> Titanium is a lot of great things, but it can't be made hard enough to hold up as a valve face without sacrificing strength, so the quality of the hard coating and it's application is extremely important.

> There is more than one kind of Ti alloy, and the tougher the base material is, the better the coatings will be supported.

Proper finish of the seats, and good valve guides also add into the longevity.

In plain English (sorry Gray :p) if it ain`t broke, don`t fix it. I`ve had my 07 for 2 years now (bought new of course) and I haven`t had to adjust the valves yet. I check them every 15 hours of ride time (just `cause I can) and they`re like new spec.

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