YZ125 H Fork Seal Replacement

[Ji Gantor]

I have already shown how to service a Maico and a CZ fork.
Japanese bikes are very similar.
No need to worry about stripping these babies down.

Lets start with some basic knowledge.
Some of these Japanese forks were designed with a soft spring to soak up all the bumps. But when a 90kg gent jumps them over modern jumps they bottom out, steel on steel.
So the smart Japanese manufactured some of their forks with a air valve.
This allowed the rider to  pressurize the air void inside the fork.
Air when under pressure acts like a progressive spring.
So the compressed air and the spring act in unison to help carry loads.

So for those that have never pumped air it their forks before a word of warning.
Check your manual for the correct pressure.
The forks I am servicing here can only take 17psi.
The air void inside the forks is only small so it does not take long to reach required pressure.
What ever you do don't try and fill them with a compressor!
This will blow the seals no matter how fast you are on the trigger.
Go down to your local bike shop and purchase a mountain bike fork/shock pump.
This way you can creep up onto the correct load rather than over fill and bleed off the excess.



Ji

[Ji Gantor]

I won't bore you with the strip down this time.
Just remove fork from bike, remove end cap and drain oil.
Place allan key into socket screw in the end and undo the dampner rod.
Clean all parts and place them in the order they came out.

Ji

[Ji Gantor]

Just a close up of the parts.

Ji

[Ji Gantor]

More close images of the parts.

Ji

[Ji Gantor]

Now is a good time to measure all the parts.
This will be handy if you order a spring or a PD valve.

Ji

[Ji Gantor]

The dampner rod is of interest.
Measure everything on this unit as it is the key to your forks.

Ji

[Ji Gantor]

From on the bike to stripped and clean this only took 1 hour.
Easy work and I only used tools most bike guys would have.
Oh yeah and a broome handle.

Ji

[Ji Gantor]

Good one mate.
Was there a Yamaha tool like Suzuki had for this job.
The broome handle is CZ,YZ two failure none.
But I know failure with the broome handle is coming.

This is a good time to make just such a tool.

A PD valve should be easy to install on the top of the Yami dampner rod.

Ji

[DJRacing]

Ji, this is the tool you need to make.

 

 

[Ji Gantor]

Cool DJ.
Nice tool.
I want one.

Ji