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Fork advice needed

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JimBoUK
100Club
100Club
Posts: 106
Joined: 24th May 2019
Location: Cambridgeshire

Fork advice needed

#1 PostAuthor: JimBoUK » Wed Dec 16, 2020 8:52 pm

Hi,
After battling with a rounded off Allen bolt in the bottom of one fork leg I’ve managed to dismantle the forks on my US import GPZ1100B1.
The bits I have don’t match the pictures in the manual and I’d like some advice or different pictures to help me rebuild them.

There are pictures below including the manual I have. In the manual it says the KZ1100B should have the forks to match the diagram for KZ/Z1000-K, KZ1000-M

The first thing is my springs are progressive which is not mentioned in the manual. They were different ways up in each fork leg !
Which way up should they go ?
Could they be upgrades ?

The next thing is the small springs at the bottom.
The manual shows a single spring (item 28) and a piston ring (item 27)
My forks have 2 springs where one is wound tighter than the other and no piston ring.

Any advice on all this will be really appreciated.
Thanks

D293562C-8493-4277-92E3-B7F689682075.jpeg


71E09934-D311-4296-9AF6-A1F80CFCF7EC.png


F5046CA9-7337-47ED-965B-942EBA90FD93.jpeg


10FA7FFD-AC6F-45E4-BC6D-25C8F899076B.jpeg

User avatar
Al
Hardcore
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Posts: 2916
Joined: 21st Oct 2007
Location: Farnbronx, Sin City, N.E. Hants

Re: Fork advice needed

#2 PostAuthor: Al » Wed Dec 16, 2020 10:20 pm

Progressive springs are likely an attempt at an upgrade.
Piston ring is the fragile nylon band round the top of the damper rod. Its shown in this diagram immediately below it which isnt very helpful.
B1 has one rebound spring and B2 has two. With both would differently, its a basic progressive effect the same as the main springs.
Diagram is from the Clymer manual.

20201216_220932.jpg


AL
1981 J1

JimBoUK
100Club
100Club
Posts: 106
Joined: 24th May 2019
Location: Cambridgeshire

Re: Fork advice needed

#3 PostAuthor: JimBoUK » Thu Dec 17, 2020 7:35 am

Thanks for the reply.
That’s good, I do have the piston

So what way up do the progressive main springs go and what way up do the pair of small springs go ?

Mr Bump
100Club
100Club
Posts: 382
Joined: 30th Dec 2015

Re: Fork advice needed

#4 PostAuthor: Mr Bump » Thu Dec 17, 2020 8:47 am

Fork springs will be tighter coils at the top.

Generally speaking where progressively wound springs are used the tighter (heavier) end is the end that is fixed and the lighter end is the one that moves, like valve springs.

I expect on the rebound springs it'll make no observable difference which way round they are.

Olly
'In your twenties you think you are immortal, in your thirties you hope you are immortal, in your forties you just hope it doesn't hurt too much'

Lemmy


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