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Matt_Porritt

Fork probs??

8 posts in this topic

I'm in the process of changing fork oils etc.

The manaul says the stock oil height is 130mm and 578ml of oil.

Well without the spring, nylon guide I get 130mm heigh in both forks still.. (which is good.. no oil loss in a year)

The problem i have is that i can only get 330-350mls out of each fork?

I've done forks before but not YZ ones and I'm damned if i can figure out why I can't get all the oil out.

I've pumped the damper rod and tube upside down, right side up, sideways, slowly, fast... NO MORE OIL!! :)

Anyone??

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**Ride it like you Stole it!**

Matt Porritt

99 YZ400F

Vist the Rubber Chicken Racing Online Shop

Discounts for ThumperTalk members.

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Does it really matter how much oil comes out? As long as you pump all of the old crap out.

Setting the correct oil level certainly has to be more accurate that measuring volumes? Correct?

As a side note, you may want to increase you fork oil level to 105mm instead of the 135mm setting, I found the action to be much more controllable.

John

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Well if this helps at all...

Last week I changed the fork oil. I added about 1.3 quarts of fork oil to get the forks to a heights of 100mm.

By my calculations (1qt=950ml), so about 1250-1300ml went into my forks.

Even it I only filled them up to 135mm like stock it probably would have taken at least about 1,100ml

So something does sound wrong.

Are you pumping the forks while they are upside down. And can you feel no more dampening effect because there is only air in the system?

What I noticed.. As I pumped the innner piston with the fork tube upside down is as the fork oil got pumped out the dampening could only be felt with the inner piston farther compressed towards the end of the stroke.

After I kept pumping, about 15 minutes, my arms were extremely tired but you should notice that there is no longer any dampening force through the entire range of the piston.

If there is still some dampening effect then there is still oil in the system.

Good Luck.

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Yeah.. I've been thinking..

There is some damping when trying to pull out the damping but none when pushing back in.

SAlso the other think I though was funny was that when the forks are bleed etc and you pull the rod out, should the thin rod that fits inside the damping rod extend an spew oil out?

I'm sure I remember it hapening on some KX500 forks I did but on the YZ4Fs i get nothing from both of them..

HELP.. I'm going nutty!! :)

------------------

--

**Ride it like you Stole it!**

Matt Porritt

99 YZ400F

Vist the Rubber Chicken Racing Online Shop

Discounts for ThumperTalk members.

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Matt,

If I remember correctly,

there was very little if any dampening on compression as I was draing the oil.

But there was rebound dampening until all the oil was drained.

But as the oil was drained the dampening moved farther down on the stroke.

Example.

compress the fork fully and pull, as the oil drains, dampening will be present over less and less travel.

Only until you compress the fork fully and then start pulling, and you know that you are only sucking air, are you done.

As for the center rod. I didn't remove this item, so I can't answer your question.

It sounds like you still have more oil to pump out.

John

[This message has been edited by John in Long Beach (edited 07-30-2000).]

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Hey guys,

Not that I'm trying to plug other sites but you may want to pose your question to an expert, Jeremy Wilkey, on www.dirtrider.net. He has his own forum there. I will blatantly give my support to him though. He runs MX-Tech which is a great place to send your forks or shock for any suspension work. He is very knowledgeable, and a really nice guy, and does excellent work. MX-Tech recently won a suspension shootout on YZ forks in Motocross Action against all the big dogs. Anyway he will most likely and have definitive answers to your questions. Hopefully nobody will take offense to me advocating MX-Tech or the other forum site, I'm just providing the information and my experience with them, everyone can use it for what it's worth. This, of course, is not meant to take anything away from the #1 WR site.

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I had my forks re-valved through Pro Action (good rating through MXA). I was bummed to see they didn't fare so well against the other guys, save Pro Circuit and Enzo Racing.

Hey what the heck, I had $300.00 burning a hole in my pocket anyways...

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99 WR, all YZ mods, de-octopused, OEM YZ tank and IMS seat, jetting by Clark/James, got forked by Pro Action, DSP airbox, PB Header, Stroker SX-1, Thumper Rad Guards , Acerbis Hand Guards, WAITING IMPATIENTLY FOR MOAB, boning up on my sheep shearing skills!!

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