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TOPIC: Forks KZ750H

Forks KZ750H 05 Jan 2019 16:07 #796212

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Going to replace the fork oil and seals. I have a KZ750 B1 but the forks are from a KZ750 H (not sure of the year-'80 or '81). What is the best oil to use for these? And how much? Thanks in advance for any suggestions.

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Forks KZ750H 05 Jan 2019 16:34 #796216

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This should answer your question


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Forks KZ750H 05 Jan 2019 17:08 #796218

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Thanks for this!

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Forks KZ750H 06 Jan 2019 21:03 #796325

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Here is mine with 05 gsxr1000 front with cognito front hub and KZ hoop. I haven’t had an issue with ground clearance. Zrx1100 swingarm and a 180 rear tire
1981 KZ750e
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Forks KZ750H 07 Jan 2019 06:28 #796334

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The manual says to use 10W fork oil, but some guys go with 15W. I use Bel-Ray fork oil. The 750-4 pdf manual has the fork free spring length spec. To pull the seals I use an off-the-shelf seal puller from the auto parts store & use milk jug plastic to protect the fork tube lowers. A small scrap of wood could be used, but the plastic works better. Be sure to use a hardened allen socket or brake caliper socket to remove the bottom allen bolts. a cheap tool could twist & damage the bolts.

1981 KZ650-CSR forks. the 750H forks should be the same.



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Last edit: by martin_csr.

Forks KZ750H 07 Jan 2019 09:42 #796348

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martin_csr wrote: The manual says to use 10W fork oil, but some guys go with 15W. I use Bel-Ray fork oil. The 750-4 pdf manual has the fork free spring length spec. To pull the seals I use an off-the-shelf seal puller from the auto parts store & use milk jug plastic to protect the fork tube lowers. A small scrap of wood could be used, but the plastic works better. Be sure to use a hardened allen socket or brake caliper socket to remove the bottom allen bolts. a cheap tool could twist & damage the bolts.

1981 KZ650-CSR forks. the 750H forks should be the same.




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Where can I get the inertool from?

1981 KZ650-D4, with 1981 z750L engine (Wiensco 810 big bore).

Project:
www.kzrider.com/forum/11-projects/607213...sr-1981-z750l-engine
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Last edit: by gordone.

Forks KZ750H 07 Jan 2019 11:51 #796354

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gordone it´s the screw with the two nuts threaded in the socket

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Forks KZ750H 07 Jan 2019 13:17 #796359

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Where can I get the innertool from?

Note: that homemade fork tool does not fit all forks. Assuming your forks are the same:
It is very simple >> Left-hand reverse threaded bolt w nuts. plus masking tape so it fits tight inside of a socket wrench.
The head of the inner cylinder is the same as a 19mm 12-pt socket wrench. use whatever fits that size socket. so get a bolt with 19mm head.
Someone else used a long bolt w a nut welded to the end of the bolt (see new pic. welded nut not shown).
In the USA. I used a 1/2 inch SAE bolt. a 3/4 inch wrench fits the bolt head. 3/4 inch = 19mm (approximate).
Note: bolts are sized by the diameter of the shaft, not the head of the bolt.


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Forks KZ750H 09 Jan 2019 16:50 #796457

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I used a broom handle and that worked for me.

I've had success using just an impact wrench too.
1981 KZ750 LTD

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Forks KZ750H 13 Jan 2019 06:39 #796669

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What is these part, make the spring more stiffer ?
I don`t have it...

1981 KZ650-D4, with 1981 z750L engine (Wiensco 810 big bore).

Project:
www.kzrider.com/forum/11-projects/607213...sr-1981-z750l-engine
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Forks KZ750H 13 Jan 2019 07:43 #796676

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Fork spring spacer. It adds tension to the fork springs. When installing the fork caps, you should feel the spring tension.
You'll have to decide if the spacers are needed. Someone may have installed longer springs or something. ???



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Forks KZ750H 13 Jan 2019 13:14 #796702

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martin_csr wrote: Fork spring spacer. It adds tension to the fork springs. When installing the fork caps, you should feel the spring tension.
You'll have to decide if the spacers are needed. Someone may have installed longer springs or something. ???...


The spacers are definitely required, they were there from the factory on the 750 LTD models. They shared the spring with other models with shorter forks, and therefore needed the spacer for the longer forks of this model.

Just re-read gordone's question and martin_csr's answer again. martin_csr is right, you'll just need to see how much tension is on the spring. If it's the original spring you'll need to make something up to replace it.
1981 KZ750 LTD

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Last edit: by Irish Yobbo.

Forks KZ750H 14 Jan 2019 22:51 #796792

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Hi all.

I cannot see the spacer on these diagram ?
www.partzilla.com/catalog/kawasaki/motor...nt-fork-80-kzy-50-e1

I have these spring set:
www.z1enterprises.com/fork-spring-kit-11-1106.html

How do I figure out what spacer I need to mine bike ?
1981 KZ650-D4, with 1981 z750L engine (Wiensco 810 big bore).

Project:
www.kzrider.com/forum/11-projects/607213...sr-1981-z750l-engine

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Forks KZ750H 15 Jan 2019 06:48 #796798

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The fork caps should be under spring pressure. In general with fork caps removed: the fork springs & spacer should reach to about the top of the fork tubes when the forks are fully extended. maybe slightly above the top of the tubes. If yours don't have a spacer, then the springs should reach the top of the fork tubes or slightly above, so that the fork caps will be under spring tension when you install the fork caps.

You could measure your fork springs then compare that measurement to the fork free spring length listed in the Kawasaki service manual. If your springs are shorter than the stock measurement, add a spacer to make up the difference. Some guys add a longer spacer to get more pre-load on the springs to compress the springs more. Whether or not you need a spacer, there should be a fork spring guide above the springs. It looks kind of like a washer.

Fork Spring Free Length from the KZ750-4 pdf. pg 211.
KZ750-E = 497 mm USA. or 477 mm for Europe or Non-USA models.

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Last edit: by martin_csr.

Forks KZ750H 15 Jan 2019 08:50 #796814

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martin_csr wrote: The fork caps should be under spring pressure. In general with fork caps removed: the fork springs & spacer should reach to about the top of the fork tubes when the forks are fully extended. maybe slightly above the top of the tubes. If yours don't have a spacer, then the springs should reach the top of the fork tubes or slightly above, so that the fork caps will be under spring tension when you install the fork caps.

You could measure your fork springs then compare that measurement to the fork free spring length listed in the Kawasaki service manual. If your springs are shorter than the stock measurement, add a spacer to make up the difference. Some guys add a longer spacer to get more pre-load on the springs to compress the springs more. Whether or not you need a spacer, there should be a fork spring guide above the springs. It looks kind of like a washer.

Fork Spring Free Length from the KZ750-4 pdf. pg 211.
KZ750-E = 497 mm USA. or 477 mm for Europe or Non-USA models.

...


When is installed the caps it needed to push the spring some together, If I remember correct the spring was aprox. even with the end of the fork.
So I can remove the cap and then measure the distance from the spring to the surface of the fork?
KZ750-E = 497 mm USA. or 477 mm for Europe or Non-USA models.

I will do that and see what I get.
1981 KZ650-D4, with 1981 z750L engine (Wiensco 810 big bore).

Project:
www.kzrider.com/forum/11-projects/607213...sr-1981-z750l-engine

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Forks KZ750H 15 Jan 2019 09:22 #796817

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If the springs are even with the top of the forks, then the springs are probably the correct length.
If the springs are below the top of the fork, then measure & add a spacer.
Note: whether or not you need a spacer, there should be a fork spring guide above the springs. It looks kind of like a washer.

Fork free spring length >> Remove the fork springs to measure.

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Last edit: by martin_csr.

Forks KZ750H 15 Jan 2019 09:23 #796818

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martin_csr wrote: If the springs are even with the top of the forks, then the springs are probably the correct length.
If the springs are below the top of the fork, then measure & add a spacer.
Note: whether or not you need a spacer, there should be a fork spring guide above the springs. It looks kind of like a washer.

Fork free spring length. Remove the fork springs to measure.

...


Do you know the Kawa part number for the spring washer ?
1981 KZ650-D4, with 1981 z750L engine (Wiensco 810 big bore).

Project:
www.kzrider.com/forum/11-projects/607213...sr-1981-z750l-engine

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Forks KZ750H 15 Jan 2019 09:28 #796819

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The part number is in the diagram link you provided >> 44028-033 GUIDE,FORK SPRING
You could probably use washers as suggested by Z1Enterprises.com in their fork spring description.
Without the guides or washers, the fork springs will probably cause wear to the aluminum fork caps.


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Last edit: by martin_csr.

Forks KZ750H 07 Feb 2019 07:00 #798323

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Today have I measured and the distance from the top of the spring to top of the upper fork is between 8,70 - 8,92mm + the fork cap + washer also set tension on the spring with 27mm.

So my progressive spring is pushed down around 19mm.

Should these be okay ? My weight is around 110kg.

I took all measurement when there was no load on the front suspension (lifted the frame up so the wheel was free to the ground).

I have added pictures here in my project threat:
www.kzrider.com/forum/11-projects/607213...gine?start=80#798322
1981 KZ650-D4, with 1981 z750L engine (Wiensco 810 big bore).

Project:
www.kzrider.com/forum/11-projects/607213...sr-1981-z750l-engine

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