fork adjustment

[arrowlock]

Hello all ,my first post here from Oz, okay just bought 1990 fj , reasonable condition , i had a xs1100 back in 1980 , great bike , loved the shaft drive, with the fj already modified the grips because the vibration was bloody terrible , found by wrapping 3 mm thick rubber foam around twice and then covered with mountain bike tube work great , then removed all the fibreglass padding inside the slip muffler on the 4 into 1 system , sound great so all crap car drivers can hear me coming.
OKay now the help i need , trying to understand the front fork adjustment , is there both a damping adjustment and a spring preload adjust and if so how are they both adjusted ,
The left and right forks seem to have different marker positions , regards steve

[flips]

Hello all ,my first post here from Oz, okay just bought 1990 fj , reasonable condition , i had a xs1100 back in 1980 , great bike , loved the shaft drive, with the fj already modified the grips because the vibration was bloody terrible , found by wrapping 3 mm thick rubber foam around twice and then covered with mountain bike tube work great , then removed all the fibreglass padding inside the slip muffler on the 4 into 1 system , sound great so all crap car drivers can hear me coming.
OKay now the help i need , trying to understand the front fork adjustment , is there both a damping adjustment and a spring preload adjust and if so how are they both adjusted ,
The left and right forks seem to have different marker positions , regards steve

Hi there,

I'm hoping you don't have fork legs from different models.They shoud be the same 

Page 26 in the owners manual...
http://www.yamahaownershandbook.com.au/lib/download.php?f=4AY-28199-20.pdf

Check this thread for vibration issues...

http://www.fjowners.com/index.php?topic=14814.msg150190#msg150190

Hope this helps.

Cheers 

Jeff P

[Arnie]

Arrowlock,

Once you read all about the fork adjustments that Flips has steered you to, you can then accept that you need to make a few changes to the internals of the forks for them to operate properly.

First and most important is to change the springs and set sag, then you need to modify the damping.  This can be done (somewhat) by changing the fluid and/or height, but you really should consider getting either the RaceTech emulators, or the RPM fork inserts.

Where in Oz are you? If near Geelong-Ballarat area, come for a ride I'll show you the difference.  Otherwise, come to the Rally in March at Harrietville.

Arnie

[Ross1]

My recent (last 7-8 years) riding and wrenching has been on XJ 750's and 900's. Air is used in the forks to set the preload, making it very adjustable.
Just picked up my first FJ ('93 with 29k miles) and the front end is very, very soft.
Recently rebuilt the forks on a XJ 900 and (among other things) replaced the Progressive springs with Race Techs. I strongly prefer the linear fork compression, but they still use air to preload the fork
making them VERY adjustable.
Read the part in the owners manual regarding preload adjustment.
Doesn't seem like four clicks on a screw adjuster will stiffen the front end adequately.
Ordered Race Tech springs for the FJ, already have replacement seals.
How long should the pvc spacer pipe be cut to firm them up (I'm 290 lbs./131.5 kg's)?

Second ?. RPM is kind-of pricey. I understand the economics of small markets.  I also believe in the value of front end control in emergency situations, (i.e. a six point buck runs into the road. In trying to run away from its own shadow, it heads for me.)
What does the emulator do? Allow (relatively) soft suspension to firm up quickly during aggressive deceleration i.e. hitting the brakes?

How do I adjust spacer length if I buy a set of the valves?

Long couple of questions.        Thanks for the responses-   Ross

[arrowlock]

HI ,okay i probably need to upgrade fork springs ,change oil ect but initially i want to adjust the basic ,,small steps you understand because i havent worked on a bike in quite a while ,maybe i should buy the CLYMER repairs manual ,,but i just want info on the basic settings , when i adjust the preload does the damper red dot align up with the preload red dot , if not when the damper adjustment is turned it will go round and round without stopping and doesnt  appear to correspond to any markings ,thats why im guessing the preload and damper must be moved in together to align up with each other ,at the moment the very outer approx 50 mm diam nut has 3 red slotted lines that are at different position from each other ,i assume they simply come to a stop at different position when tightened

[Arnie]

My recent (last 7-8 years) riding and wrenching has been on XJ 750's and 900's.
Air is used in the forks to set the preload, making it very adjustable.
Air is probably better described as a "trimmer" for the preload.
Those forks have some static load on the springs (they don't flop around, even without air),
The air adds to the mechanical preload and progressively increases  the total spring rate as the fork compresses

Just picked up my first FJ ('93 with 29k miles) and the front end is very, very soft.
Recently rebuilt the forks on a XJ 900 and (among other things) replaced the Progressive springs with Race Techs. I strongly prefer the linear fork compression, but they still use air to preload the fork
making them VERY adjustable.
All forks that have "trapped air" above the fork oil can be described as air adjustable.  Its just a bit more time consuming to adjust the oil height (which changes the amount of trapped air) which changes the spring rate progression as the fork is compressed and nears the "bottoming" point.

Read the part in the owners manual regarding preload adjustment.
Doesn't seem like four clicks on a screw adjuster will stiffen the front end adequately.
Ordered Race Tech springs for the FJ, already have replacement seals.
How long should the pvc spacer pipe be cut to firm them up (I'm 290 lbs./131.5 kg's)?
You'll probably end up with the fork cap 1-2" proud of the fork tube with the front wheel suspended, before you compress the spring enough to start threading the cap into the fork.  However, as it is easier to cut the spacer than to add material to it (duh) try starting with the spacer long enough that the cap is 2 to 2.5" proud and cut more out if its too stiff, you'll still have the fork cap adjustment if you need a bit more. 

Second ?. RPM is kind-of pricey. I understand the economics of small markets.  I also believe in the value of front end control.
What does the emulator do? Allow (relatively) soft suspension to firm up quickly during aggressive deceleration i.e. hitting the brakes?
More that it allows the suspension to react differently depending on the severity of the obstacle encountered and your speed.  In an ideal world, you wouldn't feel expansion strips, and hitting a deep pothole would not bounce the front end of the bike into the air. The goal is to keep the tire in contact with the road, and not physically upset  the bike or rider.

How do I adjust spacer length if I buy a set of the valves?
Hacksaw or tubing cutter works well

No worries

[Arnie]

You can get the Yamaha Owner's Handbook for your year bike online at:

   http://www.yamahaownershandbook.com.au/index.php

AND ITS FREE !!

HI ,okay i probably need to upgrade fork springs ,change oil ect but initially i want to adjust the basic ,,small steps you understand because i havent worked on a bike in quite a while ,maybe i should buy the CLYMER repairs manual ,,but i just want info on the basic settings , when i adjust the preload does the damper red dot align up with the preload red dot , if not when the damper adjustment is turned it will go round and round without stopping and doesnt  appear to correspond to any markings ,thats why im guessing the preload and damper must be moved in together to align up with each other ,at the moment the very outer approx 50 mm diam nut has 3 red slotted lines that are at different position from each other ,i assume they simply come to a stop at different position when tightened

[Ross1]

I'm new to the FJ world, but bought the Haynes book and it is pretty good.
The Clymer book for XJ 750's is barely better than nothing, and the Haynes (for 900's) is REALLY good.
There is a website ? url where you can get the Yammie service manuals on a CD or DVD for US$ 25.
That plus the Haynes book (plus this forum and maybe the British FJowners) will make you competent.
Around here, mechanics (or at least the shop) get $100.hr.  First hour you do yourself pays for all of these resources. 
Last mechanic who worked on one of my machines dumped it on his "test ride" and the shop still charged me full amt.!!!!!!
Never again.

[copper]

Here is a write-up on the RPM valves and the difference compared to others. The RPM valves made a dramatic difference compared to the my old racetech valve
http://www.fjowners.com/index.php?topic=7486.0

[Pat Conlon]

There is a website ? url where you can get the Yammie service manuals on a CD or DVD for US$ 25.

http://www.fj1100.com/main.htm

Many, many years ago I went to a dealer to see how much they wanted to remove, clean and reinstall the carbs on my FJ.
They quoted me $430.
I said "No, no, you misunderstood. I don't want to buy a new set of carbs, just clean my existing carbs..."
The service manager copped an attitude saying, "You're lucky we are even considering working on your old bike. Our policy is not to work on bikes over 20 years old."

I was not surprised to see them go out of business the following year.

I have learned so much on this forum. What a great group of guys. Get to a rally, you will see.

[arrowlock]

Okay thanks to all who replied ,,bit the bullet and bought a after market service manual ,,it will give me some tangible  info ,,lets face it ,, playing with just about anything on a bike can be potential dangerous ,,,one thing for sure i will do  is change the sprocket sizes so it doesnt rev so hard ,,they really need a sixth gear

[Harvy]

,,,one thing for sure I will do  is change the sprocket sizes so it doesn't rev so hard ,,they really need a sixth gear

Steve, 18 (1 up) on the front is as large as you can go without the chain contacting the sprocket cover. 38 on the rear is about as small as you can go (good luck on finding anything less anyway) without excessive chain contact on the top of the swingarm protector.

Cheers
Harvy