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Discussion Starter #1 (Edited)
Hello guys,

When I let off the throttle my 1987 will dive a little bit (as if the deceleration is too abrupt or as if the brakes had been applied for a split second). With automobiles I always associate this with worn and busted motor mounts, but I don't think that's the case with the TW. I did adjust the chain a while ago and it is in spec.

I'm inclined to believe this is a sign that my front springs are totally shot. Any other thoughts? Edit: I believe it is the front springs because when riding, if I apply the brakes, the bike dives much more sharply than my 1990. I did change the fork fluid in both bikes to ATF at the same time with the same fluid, so the only differentiation between them is the springs.

On that note, there's a bit of a squeak if I'm going slow over bumpy terrain. I do grease the swingarm all the time. Could my monoshock need replacement? I'm sure it can't be in good condition at 26 years old!

Thanks in advance,
-Craig
 

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How many miles on your 87 Craig? My 87 has under 2000 miles on it and the front end has never been apart to my knowledge. I can straddle the bike, hold the brake and compress the forks almost all the way. It really is a pogo-stick front end and feels like it too. It is coming apart in a couple months for fresh fluids, etc. It certainly does dive when I hit the brakes. Did you go by the specs when you filled it back up? I have heard of many bikes not having enough fork oil from the factory and after being changed and filled to the correct level, it was somewhat better. They are pretty soft anyway.

Mine is as old as yours and the rear shock is fine. You might just have to grease the pivot points on the shock to get rid of the squeek.
 

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Discussion Starter #4
How many miles on your 87 Craig?
Unfortunately I have no idea as my original speedo was obliterated about four and a half years ago. I want to say it has around 3-4k.


Did you go by the specs when you filled it back up? [/QUOTE ]

Yeah. It was underfilled a bit but not to the extremes of some of the stories you hear around here. I have 10w fork oil, but I like to run ATF because I feel like it cleans as well as gives a little life to the seals.


[QUOTE ] You might just have to grease the pivot points on the shock to get rid of the squeek.
I wasn't even aware of this as a maintenance item, I thought the swingarm was the only place with grease fittings - I'll do this immediately!
Thank you so much for the feedback, I appreciate it!



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Discussion Starter #5
Just trying to cover the basics: But are your fork seals in good shape, ie. not leaking?
Surprisingly they're in excellent shape. I have a replacement set on the garage shelf just waiting for the day they fail though.

If I wind up swapping springs to deal with the front end dive, I'll probably just do them at that time though (along with the steering and wheel bearings).

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note: there are not grease fittings on the shock, you would have to remove and grease the bolts or oil them.
 

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Slip your springs out of you '90 and stick them in your '87. That'll sort it out pretty quick.

Make sure both front ends have identical length spacrs. P.O.'s can do some funky stuff.

Also make sure the springs are of the same length and gauge and that the P.O. hasn't installed a poor choice in progressives, er sumpin'.
 

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Discussion Starter #8
Slip your springs out of you '90 and stick them in your '87. That'll sort it out pretty quick.

Make sure both front ends have identical length spacrs. P.O.'s can do some funky stuff.

Also make sure the springs are of the same length and gauge and that the P.O. hasn't installed a poor choice in progressives, er sumpin'.
Will do Sir! I've had that '87 since '03, but I never noticed that the dive was so out of line until I started riding the 1990. I'll check 'em out, although I'm pretty sure the '87 is bone stock. When I picked it up back in '03, it had been in a garage, untouched (literally) for 11 years, just covered in filth.

Ultimately, if they're just worn out, I think I might get the slightly stiffer 0.60kg springs that ProCycle sells.
 

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When you do the spring swap note the oil level on each set of forks. If there is a major difference that could be the problem also.

In the old days before adjustable damping and rebound we used to make minor final adjustments to the forks by using different weight fork oil. That would be after we had the correct rider sag on the fork springs and after playing around with the oil level.
 

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Discussion Starter #10
Swapped springs and the '90 started diving like a dolphin. Interestingly enough, the '87 improved but not to the level the '90 was at with the same spring.

I "checked" the fluid levels by draining and refilling.

I think I'm going to buy a stiffer front spring set, but now I have to decide between the 0.60kg and the 0.70kg...

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Sorry for bringing this up after the fact but if it were springs alone your '87's front end should now function identically to your '90.

Since you say that it improved but is still less than adequate you probably have a secondary problem.

Another cause of slushy forks are the little white teflon seals at the top of the orifice tubes. If they're worn, missing or have gouged the inside bore of your fork legs you'l get very little fork action because the gap will act like extra orifices. You may want to tear the forks down and check or even your new springs may be munny out the window.

 

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Discussion Starter #12
I'll definitely check that out - I wasn't even aware of those before.

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Since the two fork springs likely have the same outer diameter and close to the same number of coils, the accurately mic'ed diameter of the spring wire should determine the rate spring you might want. That should show in the specs of the spring you are considering. If not call and ask.

Also, a spring that has been over worked may lose some if it springieness and may not measure up to it's original strength. We call that a sacked spring.

From what you report it sounds like the spring is the major culprit with the other variables mentioned by LB along with possible small differences in oil level and viscosity. Viscosity of fork oil will break down over age.
 
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