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Discussion Starter · #1 ·
Quick question for those who have experience with fork swaps: Do you think a difference in diameter of 1mm is too much to be taken up in the triple clamps? For example: Say I have a fork tube that is 51mm O.D. at the top clamp and I tried to install that in the FZ-09 upper triple which is designed to accept a 50mm O.D. fork tube.

Any feedback is welcomed.
 

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I'm pretty sure you'd have to machine out the clamps by 1mm.
 

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1 mm diameter difference requires different triple clamps.
 

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Yeah, 1 mm is actually pretty significant... even thou it doesn't sound like much.
 

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Discussion Starter · #5 ·
I'm pretty sure you'd have to machine out the clamps by 1mm.
1 mm diameter difference requires different triple clamps.
Yeah, 1 mm is actually pretty significant... even thou it doesn't sound like much.
Thank you for the insight guys; I was not certain if the tolerances allowed for a little wiggle room. In real terms, the stock FZ-09 upper stanchion actually measures 50.21mm O.D. on my bike. The fork in question measures just shy of 50.9; a mere 0.7mm over. Probably still worth doing properly; damn short-cuts never work!
 

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You could have your stock triple clamps bored out.

Have you checked the length of your replacement forks? when I was doing the research, every fork I considered was 2-3 inches too short and that is too much diffetence to make work very easily.
 
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YES it matters
 
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Discussion Starter · #8 ·
You could have your stock triple clamps bored out.

Have you checked the length of your replacement forks? when I was doing the research, every fork I considered was 2-3 inches too short and that is too much diffetence to make work very easily.
They are about 1.75 inches shorter than stock but there is a fork cap extension available for relatively reasonable cost. Still taking initial measurements to see if I want to go hog wild. Did the same conversion on my old FZ6 and it was phenomenal...a lot of work though:

 

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What are the forks from?

Did you use the FZ6's triple clamps?
 

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Discussion Starter · #10 ·
What are the forks from?

Did you use the FZ6's triple clamps?
Sorry I never responded to this; been slacking with my forum following the past few months!

The forks are Showa BPF's removed from a 2009 Kawasaki ZX6RR. I used modified versions of the stock ZX6RR components to complete the conversion (ZX6RR Upper and Lower Triples Modified, Custom steering stem to fit the FZ steering tube, ZX6RR Wheels, Brakes, And Fender, Modified FZ rear swingarm to accept ZX6RR rear wheel and brake caliper). It was relatively involved.
 

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Revalving the stock forks is simpler and easier.
 
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Changing one set of USD forks for another is kinda pointless, especially when you've already got radial brakes.
Respring and revalve the stockers.
I've had a gsxr 711, 88 model frame, upgraded to 91 model USD, then upgraded again to K4 1000 forks in the 91 yokes, because that got me radial brakes, too. Also saved 4.4 kgs off the front end.

My Vfr has 05 gsxr 600 forks. But thats upgrading from the spindly conventional forks, and horrible brakes.
re working the fork internals is a better way to upgrade.
 

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I retrofit GSXR cartridges into all kinds of damper-rod based forks. For the FZ replace the guts of the dead leg with useful guts, lengthen the assembly and unless you gotta have adjustable features on that side, don't even need a different fork cap. it's not very hard actually.
 

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I retrofit GSXR cartridges into all kinds of damper-rod based forks. For the FZ replace the guts of the dead leg with useful guts, lengthen the assembly and unless you gotta have adjustable features on that side, don't even need a different fork cap. it's not very hard actually.
How do you lengthen the internals?
 

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For the FZ replace the guts of the dead leg with useful guts, lengthen the assembly.
How much are you lengthening it and are you also compensating by raising the rear or sliding the fork up in the triple trees to keep the same geometry? Or have you found through testing that a longer fork works better in the FZ-09 application?

Terry
 

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I'm lengthening the donor GSXR guts, the end length of the fork is the same as OE.
Oh ok I thought you were leaving the OEM damping cartridge stock and then installing a GSXR donor cartridge in the slave leg, Sort of lost me as to exactly what you were doing and why.

Terry
 

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The OE suspension is shite to put it nicely. The OE cartridge is fine as a starting point - just revalve it. The 'dead' leg can be solved 2 ways.

1) put a base valve in it, and replace the dummy rod end with one that's useful.

2) toss the entire internals and put a cartridge assembly from a GSXR instead. But since the GSXR is too short, the rod needs to be lengthened to match and said adapter convert from the GSXR rod's thread to the Yam OE fork cap.
 

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The OE suspension is shite to put it nicely. The OE cartridge is fine as a starting point - just revalve it. The 'dead' leg can be solved 2 ways.

1) put a base valve in it, and replace the dummy rod end with one that's useful.

2) toss the entire internals and put a cartridge assembly from a GSXR instead. But since the GSXR is too short, the rod needs to be lengthened to match and said adapter convert from the GSXR rod's thread to the Yam OE fork cap.
Putting a base valve in the slave with a new rebound holder would still yield nothing but compression damping as you would not get any rebound unless you closed off the ports at the top of the cartridge tube.

You can purchase a new OEM damping cartridge for right around the $157.00 mark so that would seem like a logical step if one wanted to take that direction and have a damping cartridge in each leg. Not sure what years GSXR cartridges you are using but some of them have drastically more restrictive compression valves compared to the OEM FZ-09 valves.

There are a few companies that make a very well performing fork setup using a single damping cartridge or one could even revalve the stock valves and be good to go.

Terry
 
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