Front fork issues on 98 YZ125

mox69 · Apr 11, 2007

My sister just picked up a 98 YZ125.

I was going through checking everything out tonight and I noticed a weird issue with the front suspension.

I was pushing it up and down just getting a feel for the suspension and I noticed the fronk fork was not compressing down at all. I walked it forward a few steps, slammed the front brake, and the front didn't dive at all.

I took it for a test drive down a paved road, obviously I couldn't tell much. It was raining and after I got off it was obvious that the front forks had been compressed a bit (first 1-2in was clear of water, rest of the lower part had water on it).

While loading it into the truck and ratcheting it down it would compress in chunks...If that makes any sense. I would ratchet it with the tie down and the front fork wouldn't move, then all of the sudden it would unstick and move an inch or so. Did this a couple times and got the same result each time, few ratchet clicks, unstick and move an inch.

I have a very basic knowledge of suspension, but I know something is wrong here.

Anyone have any ideas?

mox69 · Apr 13, 2007

Hmm alright let me start with a simpler question and go from there.

What would cause the front suspension to bind up and become "sticky."?

mandark1967 · Apr 13, 2007

The stiction and non-responsiveness is likely due to the seals being blown and the oil inside becoming gummy.

At a minimum, I'd recommend

Draining any remaining fork oil
Replacing Seals and Bushings
Replacing oil

you should be okay after that if there are no large nicks in the legs

mandark1967 · Apr 13, 2007

mox69 said:
My sister just picked up a 98 YZ125.

I was going through checking everything out tonight and I noticed a weird issue with the front suspension.

I was pushing it up and down just getting a feel for the suspension and I noticed the fronk fork was not compressing down at all. I walked it forward a few steps, slammed the front brake, and the front didn't dive at all.

I took it for a test drive down a paved road, obviously I couldn't tell much. It was raining and after I got off it was obvious that the front forks had been compressed a bit (first 1-2in was clear of water, rest of the lower part had water on it).

While loading it into the truck and ratcheting it down it would compress in chunks...If that makes any sense. I would ratchet it with the tie down and the front fork wouldn't move, then all of the sudden it would unstick and move an inch or so. Did this a couple times and got the same result each time, few ratchet clicks, unstick and move an inch.

I have a very basic knowledge of suspension, but I know something is wrong here.

Anyone have any ideas?

I'm referring to the section that I bolded in your post:

I mention this because once you correct the fork issue I'd hate to see them go bad again...

When you are hauling a bike, try using a wooden block or some block type thing between the top of the front tire and the Fender.

This way, when you hit bumps in the road, your bike suspension doesnt compress and cause the tie downs to come loose. It also causes suspension problems when you ratchet them down real tight. It has something to do with causing seals to pop when hitting bumps...I wish I could point you to that post, because it was quite detailed in why you should use a block between the tire and fender when hauling

mox69 · Apr 13, 2007

Alright I think your saying stick a wedge between the fender and tire, so when I hit a bump the forks cannot move?

The previous owner indicated the seals were changed recently. I'm wondering if he goofed something up while doing this. I will order up a set of seals , bushings and some fork oil

Thanks for the help guys.

motodr9 · Apr 24, 2007

Hey Mox,

-Could the forks be overfilled with oil? Correct wt. oil?
-Are the forks aligned on the front axle?
-Perhaps there is damage, or a botched rebuild?
-Could it be sprung for a extremely large, very fast man?

Get in there... check it out, and report back.

mandark1967 · Apr 24, 2007

It could also be sprung for a short, slow FAT man like me ;)

mox69 · Apr 24, 2007

Well I've been neglecting the 125 as of late because my CR250 is keeping me busy.

I rode the YZ through some pretty rough terrain the other day and it really didn't seem that stiff. I hope to find some time this weekend or next weekend to look at the forks more.

My sister had no trouble taking it over rocks, trees, etc last time we went out, so I'm not super concerned about it. This bike won't see much action outside of trails and dirt roads.

I picked up some 5w fork oil last weekend. My first step is to drain all of the oil in there out, and put this stuff in. I don't have a shop manual yet, so I really need to figure out how to actually drain and refill the shock oil first.

I'm guessing whoever did the last fork seal job messed something up. I'm going to inspect the forks really good as well.

mox69 · May 1, 2007

Well I had some time to give the YZ a good once over after a short ride this weekend. I found a few things.

1. The front forks are leaking oil.

2. At least one of the front seals has come half way out of its proper position.

So I guess I have a new question. What would cause a fork seal to pop out?

This bike has not been jumped or rode very hard at all. Light trail riding and dirt roads.

IndyMX · May 1, 2007

Have you opened the bleeders on the tops of the forks yet?

mox69 · May 2, 2007

Nope I am a noob when it comes to suspension. I assume those are two smaller bolts at the very top of the forks?

I will open those up this weekend.

IndyMX · May 2, 2007

mox69 said:
Nope I am a noob when it comes to suspension. I assume those are two smaller bolts at the very top of the forks?

I will open those up this weekend.

There are two screws on the caps of your forks.. One is the bleeder and the other is the "clicker".

The clicker is usually dead center, the bleeder is towards the outer edge of the cap.

ShaneG · May 3, 2007

I have a 98 yz125 as well and though my bike did not does as your is, mine were busted from underjumping table tops(couldn't find the courage to jump all the way, but now I do :P). I had them rebuilt for 90 dollars including the seals and fluid and everything. I can point you in that direction if you need me to!

motodr9 · May 5, 2007

Loose seal

Mox,

You will need a seal driver (for your fork size) to fix this. Grab a manual for the bike also, it will pay for itself many times over.
Option #2 is to take your forks to a local suspension shop; find a good one. You may want to have the shop change the oil in the shock too.

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