Correct Fork Oil Level

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doakley
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Correct Fork Oil Level

Post by doakley »

So I just finished the shim stack mod to my forks. Took out 2 of the 10 shims as recommended. Whether it makes them better or not I'm really glad I took them apart. The right fork had a lot of crud in the bottom. So much that one of the metering holes in the valve was completely clogged with grunge. I'd suggest anyone who hasn't taken their forks apart ever, might want to do this.

My Cyclepedia manual ('99 KDX 220), says the correct fork oil amount is 530 ml and to add or remove oil to a height of 85-89 mm. The problem is 530 mm is no where near the correct amount of oil to reach 85-89 mm. I had to add a lot of oil. (Fork compressed, spring removed, rod down.). I put them at 87mm and will have a better idea after I ride this weekend.
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Correct Fork Oil Level

Post by canamfan »

Sounds like your measuring correctly. I have run between 4 and 5 "s which would be 100 to 125 mm. I ran less and blew out a fork seal on a g-out.
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Re: Correct Fork Oil Level

Post by KDXGarage »

If they mean the amount of oil during a change, it will be less than when you did it more properly and completely cleaned it out.
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Correct Fork Oil Level

Post by doakley »

I wondered that too. I'll know more after tomorrow. Finished the fork shim mod and the top end rebuild this morning before going to work. Had the cylinder re coated by Millineum (really nice job, shout out to them). I let them do the KIPS valve too. Finished the reassembly this morning and it fired on the first few kicks. I ran it through one heat cycle and will do another in the morning before riding later in the day. So far it looks and sounds great.
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Correct Fork Oil Level

Post by doakley »

Reporting on results of fork shim mod on my 1999 220:
I followed the instructions in the thread on the fork shim mod elsewhere in these forums. I did have to make a damper rod tool and those instructions are in these forums as well. More difficult to take the forks apart than I had thought but still straightforward. I removed 2 shims from the stack and reassembled everything.

Test ride was at Battery Park , SC, where they have a poorly maintained MX course but a lot of woods trails, some with some nice roots exposed. The shim mod has definitely made an improvement in the forks initial reaction to sharp abrupt bumps like roots, etc. Tracking seemed improved considerably with less tendency for the front wheel to be kicked off line when hitting things. This mod does not affect the overall action of the forks, just the initial impact from roots, rocks, ruts, etc. much better. If you don't want to spend the money on a Gold Valve install, I'd suggest doing the shim stack mod. It is free and if you don't like it you can always put it back to stock configuration.

I'm going to stick with the current fork oil level and ride it as is for a bit although I'm thinking I'll probably end up dropping the level just a bit eventually to suit me better.
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Re: Correct Fork Oil Level

Post by doakley »

Update on fork mods. I reduced the oil level from 87.5 to 95MM (stock is 84-89mm). NOW I am happier with the total fork action. Test rode this week at Battery Park, SC again. I wanted to ride the same MX track and trails as before to try to get a good comparison on the forks. I'm pretty slow and I think I'm going to like this oil setting much better. Racing this Sunday in the NC foothills on more difficult terrain so this should be a good test.
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Re: Correct Fork Oil Level

Post by doakley »

Rode in the MidEast Racing series hare scrambles at Welborn Farm, NC. Happy to report the shim stack mod and fork oil level adjustment made a huge difference in the bike. It was blazing hot and humid but the bike performed well even if I did not! Really glad I went to the effort to make this modification. The course was rocky and rooted up and the forks just took this pretty much in stride.
I highly recommend doing the shim stack mod.
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