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Markopolo400

Stock Shim Size on yz400f?

4 posts in this topic

Well, I am adjusting my valves for the first time, and this morning I just got my valve buckets and shims out.

Upon closer inspection of the shims, I realized that they were all different, and they didn't end in a 5 or 0. Instead of being a 175 or 180, they are 178, 172, etc.

So do all bikes come from the factory like this? Or did someone adjust the valves already? 'Cause they are out of spec, and if someone already adjusted them, and I have to again, then it's time for new valves and springs. :thumbsup:

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The factories have the shims in all sizes. WE mortals on the other hand have to settle for larger increments. There can be no stock/standard size due to machining tolerances changing from engine to engine. Hopefully you recorded your clearances before you removed the shims and you also know each shims original location or you get to start over.

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Dont jump to change valves and springs just because the clearance was off. Do a leak down test if in doubt, but just adjust them to specs for now.

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Ok. Thanks. :thumbsup:

It looks like these are the stock shims. My clearances were on the tight side, and I did write them down before pulling the cams.

I was a little worried about digging into my 4-stroke motor, but it's not bad at all.

I'll reshim, and my bike should be back on the track on Wed. :ride:

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