Yamaha forks - What does this mean?

lwsmithjr

~SPONSOR~
Sep 18, 2002
194
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I just had to replace the front fork seals on both my '99 YZ250 and my son's '03 YZ250F. While reassembling the forks, I notitced that the damper rod on the 250F would remain extended when pulled to the top, but the ones on my 250 would slowly drop back down to the fully collasped position. This was after the oil level had been set. They are not valved exactly the same, but in actuality, his are much more compliant and plusher than mine. (I've tried to no avail to get mine to ride as good as his, but no luck.)

Does this indicate a problem with my forks? They are extremely harsh over chop and braking bumps, but still bottom out when I mess up. Is there something I can tell from this difference between the two? One other thing -- The mid valve in the '99 250 forks has the Race Tech recommended "Check Plate" modification. I think that means there is no compression stack in the mid-valve

Thanks for any help!

Len
 

marcusgunby

LIFETIME SPONSOR
Jan 9, 2000
6,450
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Some kybs have a bleed shim stack on the base valve-this really makes a difference as you dont have a free bleed like on some other kybs.Not sure on those models you describe.

If yours are not working as well as his you may consider reinstalling the shims on the mid valve.
 

lwsmithjr

~SPONSOR~
Sep 18, 2002
194
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Thanks Marcus. I knew I could count on you.

Two issues:
1) Does the bleed shim stack give you better action. In other words, which way is best?
2) I don't have a clue as to what the mid-valve stack looked like. It was this way when I bought the bike. Without completely disassembling the 250F's cartridge, how do I know where to start?

Thanks Again!
 

marcusgunby

LIFETIME SPONSOR
Jan 9, 2000
6,450
2
Thats a good question on the bleed shim stacks, i dont honestly know-my feelings are they are a good idea on a heavy bike or one that puts alot of weight on the front wheel, but i would also think about using a lighter stack than the ones fitted.

Some forks work well with them, but OEM constantly swaps year to year if they have them or not, so they cant seem to decide either.

On the mid i have thought about it a little more and its not going to be easy to rebuild a std midvalve, its not really hard ,but i think they remove spacers and such to get the check plate to lift alot.You going to need alot of parts -the cr125 has about 25 shims on the mid but only half of them are really used.
 
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