valve shim yz400f

1 reply to this topic
  • nolzey

Posted November 30, 2007 - 02:16 AM


i am in the process of shiming the valves on my yz 400f, it has done 20 hours since the head was rebuilt. the machinest reseated the valves and re faced the valves. he told me he set the tollerances and i didnt check them:( he also said they wernt seating well before the work. turns out 1 of the intake valves have been open since, but the bike still run good. i took the shim (175) out and put the bucket on and it measures 0.240mm which is not to far off what i want. should i just run it like that and sell it or try and skim down an old shim to take the 0.09mm off the tollerance. i dont think they make a 0.10 shim. the other option is too put new seats and valves in but i dont want to spend anymore on this bike. i'de rather put that money into a new bike. but i dont want to sell a complete dud:(

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  • grayracer513

Posted November 30, 2007 - 07:51 AM


If you try to run them without shims, the bucket will contact the spring retainer instead of the valve stem, and the results will be, um...very bad. You'll get a bogus reading, too.

Try a 160 or 155 shim to see what the actual situation is, and go from there. As you put the bucket down over a new shim, give it a few light taps with the butt of a screwdriver to seat the shim squarely before taking your measurement.

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