Front fork oil/change

[delvryboy]

I am going to replace the seal in a few weeks as they leak pretty bad. In the mean time I wanted to replace the oil (or at least bring it up to proper level). I couldn't really find a write up with the forks on the bike. Any links?

Thanks

[yamaha_george]

I am going to replace the seal in a few weeks as they leak pretty bad. In the mean time I wanted to replace the oil (or at least bring it up to proper level). I couldn't really find a write up with the forks on the bike. Any links?

Thanks

Hi,
You will not find that here as leaving the forks on the bike is asking for trouble.

In case you wonder why it is because the old oil contains minute bits of old shock internals material which settles as sludge in the bottom of the fork leg, most FZR legs have no drain point on them that is low enough to wash the cr*p out !.

The idea is to completely strip the forks, wash & clean them.

For tools (how to make yer own ) & how-to look at :-

http://www.saltmine.org.uk/fzr/fork.html

yes I know it says about emulators and such but the procedure for stripping forks & putting new seals is outlined.

[delvryboy]

I'm going to strip them down next week. However, its my only work transportation for the next few days an I want to at least make sure I have the proper level of oil in them.

[haunter]

you just unscrew the tops and add oil as needed

[mszilves]

The idea is to completely strip the forks, wash & clean them.

For tools (how to make yer own ) & how-to look at :-

http://www.saltmine.org.uk/fzr/fork.html

yes I know it says about emulators and such but the procedure for stripping forks & putting new seals is outlined.

Hey george, just read your write-up, and looking at the pics of your PD valves, I notice that they have 3 little holes in them (according to Racetech these are the low-speed compression damping holes). My Racetech ones only have one low-speed compression hole. Having to run 20W oil to get the proper rebound damping (anything lower just doesn't give enough rebound, since I'm running .85kg springs), I've found that it's pretty jarring on square, high-speed bumps (cracks, potholes etc), but great everywhere else. So I got to thinking what's the best way to reduce high-speed compression damping while keeping all else the same? I thought, well I'll just back off the preload springs a bit, but at 2 turns, I don't know if I want to go lower, and possibly negatively alter the low-speed compression (by having the springed valves open too soon).

So at this point, my options were:

1. Unscrew the preload springs a bit, to maybe 1-1.5 turns, and possibly affect low-speed compression
2. Get new preload springs from Racetech (apparently the stock ones are 64 lb/in, but they also have 26 and 40lb/in ones

So today I called Racetech, and to my surprise, the tech guy suggested drilling out an extra hole in the top of the adjuster. Apparently this fixes a lot of issues. At first I thought this was kinda strange since the holes are for low-speed compression damping, but he said it would help alot. After seeing yours with 3 holes, he may have a point. He said that they've found that on some of the older damping-rod style forks, this was needed.

How does your front feel? Does it have pretty good low-speed compression (hard braking) and also fairly soft on hard, jarring potholes etc? Also, any idea what those little preload springs are rated, and what weight oil you're using?

[yamaha_george]

http://www.saltmine.org.uk/fzr/fork.html

Hey George, just read your write-up, and looking at the pics of your PD valves, I notice that they have 3 little holes in them (according to Racetech these are the low-speed compression damping holes). My Racetech ones only have one low-speed compression hole. Having to run 20W oil to get the proper rebound damping (anything lower just doesn't give enough rebound, since I'm running .85kg springs), I've found that it's pretty jarring on square, high-speed bumps (cracks, potholes etc), but great everywhere else. So I got to thinking what's the best way to reduce high-speed compression damping while keeping all else the same? I thought, well I'll just back off the preload springs a bit, but at 2 turns, I don't know if I want to go lower, and possibly negatively alter the low-speed compression (by having the springed valves open too soon).

So at this point, my options were:

1. Unscrew the preload springs a bit, to maybe 1-1.5 turns, and possibly affect low-speed compression
2. Get new preload springs from Racetech (apparently the stock ones are 64 lb/in, but they also have 26 and 40lb/in ones

So today I called Racetech, and to my surprise, the tech guy suggested drilling out an extra hole in the top of the adjuster. Apparently this fixes a lot of issues. At first I thought this was kinda strange since the holes are for low-speed compression damping, but he said it would help alot. After seeing yours with 3 holes, he may have a point. He said that they've found that on some of the older damping-rod style forks, this was needed.

How does your front feel? Does it have pretty good low-speed compression (hard braking) and also fairly soft on hard, jarring potholes etc? Also, any idea what those little preload springs are rated, and what weight oil you're using?[/quote]



MS,
The ride after fitting these YSS PD valves is GREAT, I have not been able to faultthe advice of Greg @ ASR Suspension either.
Amongst all the rest of the verbiage on that page you will find that I used 15wt (my wt being 80Kg about 180lbs ) and 120mm (4.72" ) air gap with forks FULLY compressed (NO internals except the actual old modified damper rod )

HTH
Y-G

I will endeavour to ask Greg what the miniture springs are as I have no idea !

[mszilves]

I will endeavour to ask Greg what the miniture springs are as I have no idea !

Awesome thanks, any info you could find out would be great!

[yamaha_george]

I will endeavour to ask Greg what the miniture springs are as I have no idea !

Awesome thanks, any info you could find out would be great!

YUP Race tech design is out of date!!! thanks to Modern German thinking on PD valves / emulators

[mszilves]

You may be absolutely right YG... if all else fails, I may try and get you to source me a pair of those proper German ones.

[delvryboy]

I am going to replace the seal in a few weeks as they leak pretty bad. In the mean time I wanted to replace the oil (or at least bring it up to proper level). I couldn't really find a write up with the forks on the bike. Any links?

Thanks

Hi,
You will not find that here as leaving the forks on the bike is asking for trouble.

In case you wonder why it is because the old oil contains minute bits of old shock internals material which settles as sludge in the bottom of the fork leg, most FZR legs have no drain point on them that is low enough to wash the cr*p out !.

The idea is to completely strip the forks, wash & clean them.

For tools (how to make yer own ) & how-to look at :-

http://www.saltmine.org.uk/fzr/fork.html

yes I know it says about emulators and such but the procedure for stripping forks & putting new seals is outlined.

Seeing as I can't ride until I get a new VR, I'm going to start this tonight. Wish me luck.

[delvryboy]

Well, didn't end up doing the forks today. The pipe I used (as in the wiki) wasn't as stable as I would like. The last thing I needed was for it to slip and break off the oil filter. I'll figure out another method and get on it next weekend. I did pull apart the front brakes and cleaned all of the goop out from the front forks leaking and flushed the old brake fluid, so at least I accomplished something.