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Markopolo400

yz400f Valve Check/Adjustment

5 posts in this topic

Well, I am not sure if my 400 has ever has it's valves checked (Estimated 60 original hrs on bike). Yet it still starts first kick, and runs flawlessly.

I am checking the valves, and in the manual, it says to drain the coolant, and take off the rads for more room.

Is this nesscesary?

I really don't think it is, and I don't wan't to go out and get more coolant.

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No, you don't need to do that. But get a feeler gauge that is not very wide. It is easier to fit it in there. Also, when measuring, force in the largest one that will fit when measuring the upper and lower range. Getting the right size shims can be a pain, but once it is adjusted, you'll find it takes a long time before it goes out of spec again. Now if you had a Honda , you'd need to buy a shim set.

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With the YZ400's, you generally don't see valve problems because they use the steel valves stock. You should get a bucket load of hours out of that bike if you take care of it. Still a great idea to check the valves so you know where you stand.

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Well, 4 out of 5 of my valves are too tight.

As far as I know, this is the first time in 8 years that they've checked.

I'll throw new shims in it this weekend.

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