GS500F Fork springs help.

GreyGhost said:
Huh? Your logic has come off the rails Trials. Every spring moves when you put any weight on it. The distance it moves is proportional to the spring rate. 20 lbs on 20-80 lb progressive should get you ~1". 20 lbs on an 80 lb straight spring should get you ~0.25".
Click to expand...
Doesn't matter if its a Mack truck coil spring, they all work the same and you are correct an 80 pound rate spring will not move one inch unless you put a full 80 pounds on it. The second one inch of travel will require another 80 pounds (y) (linear rate spring)
 
Go to the Racetech site pointed to earlier, and pick out what spring rate you need and what part number it is. Also take note of their recommended oil viscosity. Go to your local motorcycle dealer - the bricks-and-mortar variety - and order those. Since you are in Ottawa, I would suggest 613 Motorsports ... they know their stuff and will help you out.

To do this job - presumably not involving replacing the guide bushings and seals - you will need a front steering-stem stand to get the front of the bike off the ground without the weight on the suspension. Remove brake caliper, front wheel, front fender, handlebar - you don't need to disconnect the brake caliper from the hose but you will have to support it so that it's not hanging by the hose.

Before removing the fork from the bike, remove the fork cap. Release the upper triple clamp bolt that secures the fork to the upper clamp but don't remove the lower clamp bolts yet. Spread an old towel out over your gas tank. Knock the fork cap loose and then remove it. BE CAREFUL, it is holding spring tension from inside, push down on the socket as you unscrew it so that the fork cap doesn't go flying across the shop.

The spring can now be removed, but draining the oil out requires removing the fork from the bike. Measure the distance between the top of the top triple clamp to the top of the fork tube (so that you can later put it back in the same position). Undo the lower triple clamp bolts and slide the fork out the bottom. Now you can drain it into a used oil container. Compress and release the fork a few times to get most of the oil out.

Pour some kerosene into the fork and compress and release the fork a few times, then drain that into your used oil container while compressing and releasing the fork. This is to encourage remnants of built-up crapola to get out of the fork.

Pour new fork oil to the specified level into the fork. Compress and release the fork several times to get air bubbles out. The level is normally specified with the fork compressed without the spring installed.

Re-install fork into the triple clamps to the proper height that you measured before, tighten and torque lower clamp bolts.

Install spring and fork cap, push down on the fork cap while carefully turning the cap with a socket to get the threads started. BE CAREFUL, don't cross-thread it - easy to happen because you are doing this under compression force from the spring. The compression force should be achievable by hand and should not be excessive.

Snug the fork cap then torque the upper triple clamp bolts.

Then do the other fork, then put the rest of the bike back together.

Sounds long ... it's really not that hard ... but you do need that front steering-stem stand and the right tools.
 
Brian P said:
Go to the Racetech site pointed to earlier, and pick out what spring rate you need and what part number it is. Also take note of their recommended oil viscosity. Go to your local motorcycle dealer - the bricks-and-mortar variety - and order those. Since you are in Ottawa, I would suggest 613 Motorsports ... they know their stuff and will help you out.

To do this job - presumably not involving replacing the guide bushings and seals - you will need a front steering-stem stand to get the front of the bike off the ground without the weight on the suspension. Remove brake caliper, front wheel, front fender, handlebar - you don't need to disconnect the brake caliper from the hose but you will have to support it so that it's not hanging by the hose.

Before removing the fork from the bike, remove the fork cap. Release the upper triple clamp bolt that secures the fork to the upper clamp but don't remove the lower clamp bolts yet. Spread an old towel out over your gas tank. Knock the fork cap loose and then remove it. BE CAREFUL, it is holding spring tension from inside, push down on the socket as you unscrew it so that the fork cap doesn't go flying across the shop.

The spring can now be removed, but draining the oil out requires removing the fork from the bike. Measure the distance between the top of the top triple clamp to the top of the fork tube (so that you can later put it back in the same position). Undo the lower triple clamp bolts and slide the fork out the bottom. Now you can drain it into a used oil container. Compress and release the fork a few times to get most of the oil out.

Pour some kerosene into the fork and compress and release the fork a few times, then drain that into your used oil container while compressing and releasing the fork. This is to encourage remnants of built-up crapola to get out of the fork.

Pour new fork oil to the specified level into the fork. Compress and release the fork several times to get air bubbles out. The level is normally specified with the fork compressed without the spring installed.

Re-install fork into the triple clamps to the proper height that you measured before, tighten and torque lower clamp bolts.

Install spring and fork cap, push down on the fork cap while carefully turning the cap with a socket to get the threads started. BE CAREFUL, don't cross-thread it - easy to happen because you are doing this under compression force from the spring. The compression force should be achievable by hand and should not be excessive.

Snug the fork cap then torque the upper triple clamp bolts.

Then do the other fork, then put the rest of the bike back together.

Sounds long ... it's really not that hard ... but you do need that front steering-stem stand and the right tools.
Click to expand...
Great description. If they happen to have a center stand, I just put a bunch of weight in a backpack and attach it to the pillion seat to take apart the front end.
 
Drain the old oil into a clean glass container so you can inspect it for metal particles or water.
 
If your fork oil is grey that is aluminum wear and it means it's not being changed enough. If there are flakes of black plastic like material in it that is what is left of your teflon coated fork bushings.

... if it smells bad you have biologicals in there and that means you also likely have water.
or some oil based life form :|

Water in oil makes it appear cloudy or opaque. (like coffee with milk in it)
 
Hey Brian, you don't take them completely apart to clean yours?
I clean my forks like you would clean a gun, I pull an oiled rag through everything I possibly can.
 
You'll notice that Racetech has a recommended spring calculator based on rider weight and intended use.
Very worthwhile IMO.
I ran the numbers based on a 200 lb. rider, this is what turned out:


  • Available FRSP S2938 Series Springs are:


  • RT FK SPR 29.0x377 .70kg
    FRSP S2938070
    $129.99


  • RT FK SPR 29.0x377 .75kg
    FRSP S2938075
    $129.99


  • RT FK SPR 29.0x377 .80kg
    FRSP S2938080
    $129.99


  • RT FK SPR 29.0x377 .85kg
    FRSP S2938085
    $129.99


  • RT FK SPR 29.0x377 .90kg
    FRSP S2938090
    $129.99


  • RT FK SPR 29.0x377 .95kg
    FRSP S2938095
 
Looking at the oil that came out of your forks is called non-destructive testing.
Inspecting your slide bushings for wear can prevent your fork seals from prematurely leaking and wearing out. if you replace them in time.

The oil in your forks has zero filtration system and it only contains about 400cc's of hydraulic oil in a very hostile environment,
we do everything we can to turn it into a hot milkshake by riding no matter who you are.

I was inspecting one of my bikes just now and found a bad sprocket side rear wheel bearing :/ **it happens and stuff wears out.
 
I think we ca
Trials said:
Looking at the oil that came out of your forks is called non-destructive testing.
Inspecting your slide bushings for wear can prevent your fork seals from prematurely leaking and wearing out. if you replace them in time.
The oil in your forks has zero filtration system and it only contains about 400cc's of hydraulic oil in a very hostile environment,
we do everything we can to turn it into a hot milkshake by riding no matter who you are.
Click to expand...
I think we can all agree that if the fork oil has never been changed its going to come out looking like sludge.
As for full disassembly to inspect the slider bushings, OP may save himself a lot of trouble by simply wiggling the lower fork legs while bolted in the triple clamps and see if there's any discernable movement.
Unless you're replacing fork seals, or there's a lot of slop I wouldn't be bothered.
 
Agreed. When I say I am fairly mechanically inclined, I mean I am a Heavy equipment technician. So understand everything you guys are discussing. That being said, I dont have alot of experience on bikes so I appreciate all the knowledge that can be had here. The thing that has me a good tech is knowing there is always more to learn. Thanks again

Sent from my SM-G930W8 using GTAMotorcycle.com mobile app
 
I like my stuff to work good, been destroying and fixing forks way long time, it gets to be a mindless and always messy job that takes me at least 4 hours per solo assuming I have the parts on hand and I do work slow compared to somebody doing it for money.
 
frozen said:
Agreed. When I say I am fairly mechanically inclined, I mean I am a Heavy equipment technician. So understand everything you guys are discussing. That being said, I dont have alot of experience on bikes so I appreciate all the knowledge that can be had here. The thing that has me a good tech is knowing there is always more to learn. Thanks again

Sent from my SM-G930W8 using GTAMotorcycle.com mobile app
Click to expand...
That's awesome you will have a huge leg up on being a Light equipment technician :cool:
 
150k to the west of Ottawa on highway 7 here (y) but I'm not very portable.
unless you have a Great riding area in your back yard,
that would be completely different I can be there with 2 guys pretty quick.
... maybe 3
 
You must log in or register to reply here.

Back
Top Bottom