Fork oil level GPz750

  • ThatGPzGuy
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Fork oil level GPz750

20 Jun 2015 13:38
#677471
Hey gang, I am rebuilding my forks and adding Progressive springs and cartridge emulators. I'm a little confused. The guys at Race Tech said to run the oil level at 130mm from the top forks fully compressed. The problem is the air hole is located at 210mm from the top. My Haynes manual says the oil level should be measured with the forks fully extended. Which is it?
I suppose I could cover the air hole with my finger while I add and check the fork oil but I don't recall having to do this the last time I changed the fork seals.
TIA,
Jim
Jim
North GA
2016 Yamaha FJR1300ES
1982 GPz750 R1
1974 Kawasaki H1
1976 Kawasaki KZ400
1979 Yamaha XS650 cafe'
2001 KZ1000P
2001 Yamaha YZ426
1981 Honda XR200 stroked in an '89 CR125 chassis
1965 Mustang
1967 Triumph GT6
1976 Bronco
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  • missionkz
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Re: Fork oil level GPz750

20 Jun 2015 14:32
#677482
If the two spring's free length, diameter and spring wire diameter (unloaded laying on the floor) are the same as stock, I would go with the FS Manual.
However if the wire diameter of the springs, their length and coil diameter are different then stock, then you have use the spring's "manufacturers recommendation" because they will displace a different volume of fork oil when installed.
Bruce
1977 KZ1000A1
2016 Triumph T120 Bonneville
Far North East Metro Denver Colorado

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Re: Fork oil level GPz750

20 Jun 2015 18:15
#677502
Thanks Mission. The springs are pretty close. The problem I have is the fluid runs out when I try to get the oil level at 130mm compressed. It runs out the air hole. I suppose I am supposed to plug the air hole with my finger while I fill it up and check the oil level. Just wanted confirmation. Like I said., I did this a few years ago but can't remember what I did.
It sucks I'm getting dumber and more forgetful as I age... That does not bode well. :unsure:
Jim
North GA
2016 Yamaha FJR1300ES
1982 GPz750 R1
1974 Kawasaki H1
1976 Kawasaki KZ400
1979 Yamaha XS650 cafe'
2001 KZ1000P
2001 Yamaha YZ426
1981 Honda XR200 stroked in an '89 CR125 chassis
1965 Mustang
1967 Triumph GT6
1976 Bronco
"If you didn't build it, it's not really yours"

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  • TexasKZ
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Re: Fork oil level GPz750

20 Jun 2015 19:50
#677507
I'd ask the folks at Race Tech for clarification.
1982 KZ1000 LTD parts donor
1981 KZ1000 LTD awaiting resurrection
2000 ZRX1100 not ridden enough

www.kzrider.com/11-projects/620336-anoth...uild-thread?start=24

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Re: Fork oil level GPz750

20 Jun 2015 20:03
#677511
You'd think there is a CC volume number to pour in with no springs installed so you can just assemble it.
Bruce
1977 KZ1000A1
2016 Triumph T120 Bonneville
Far North East Metro Denver Colorado

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Re: Fork oil level GPz750

20 Jun 2015 21:35
#677519
My electronic copy of the factory service manual has the compressed measurement with springs removed at 168mm + - 4mm and the volume of oil at 255cc if dry and 240cc if just oil changed. Another chart shows the extended measurement with springs removed at 382mm + - 2mm. The latter is what I used to set mine up.
Note the cheap paper copy manual I bought online had the incorrect oil level showing on their chart, which caused me to have to do the job twice as the first time I had it overfilled.
1980 kz550 c ltd.
1982 GPZ750R

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Re: Fork oil level GPz750

21 Jun 2015 05:35
#677545
Race Tech may recommend a different oil level, based on how the cartridge emulators and aftermarket springs act compared to the factory setup.
1982 KZ1000 LTD parts donor
1981 KZ1000 LTD awaiting resurrection
2000 ZRX1100 not ridden enough

www.kzrider.com/11-projects/620336-anoth...uild-thread?start=24

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Re: Fork oil level GPz750

21 Jun 2015 06:31
#677562
I used 250ml each side on mine, also wrapped the air holes temporarily with some pvc tape.
1980 Gpz550 D1, 1981 GPz550 D1. 1982 GPz750R1. 1983 z1000R R2. all four aces

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Re: Fork oil level GPz750

24 Jun 2015 04:27
#678050
Thanks everyone. I ended up using the measurements provided by race tech and covering the hole with my finger while I filled and measured. It was a little bit of a PITA but it is all together.
Now if I can just solve the idle issue...
Jim
North GA
2016 Yamaha FJR1300ES
1982 GPz750 R1
1974 Kawasaki H1
1976 Kawasaki KZ400
1979 Yamaha XS650 cafe'
2001 KZ1000P
2001 Yamaha YZ426
1981 Honda XR200 stroked in an '89 CR125 chassis
1965 Mustang
1967 Triumph GT6
1976 Bronco
"If you didn't build it, it's not really yours"

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