SV650 ZX6R F1 Fork Hybrid

So, all the rebound problems have been solved!
Turns out, pouring fork oil directly into the damping rod really stiffens it up!
I assembled the other fork, avoiding pouring fork oil into the damping rod and taking Sid Squids advice, followed all the instructions to the letter and hey presto! Nice working fork!

I had to take the other fork apart and really pump the fork oil out of the damper unit itself, and squirt a little carb cleaner in it to get it moving again, it really was rock solid!

The project has FINALLY been complete! The bike is back together and had it out for a test ride today.

So, rebuilding the fork was easy after reading the instructions properly and not filling the damper rod with fork oil

First, I measured out the standard preload setting (6 lines) and made sure there was 25mm from the base of the top cap and the inside of the rebound adjuster using a trusty biro with a mark on it at 25mm.



Then, I put the damper unit and fork sanction back into the SV lower leg, and tightened the damper unit up with the trusty long clamp



Now for my home made, cheap, fork seal driver. Basically, its a 40mm drainage pipe with a long cut down one side, slide it over the top of the fork, down to the seal, make sure the fork sanction doesn't bash against the bottom and slide the fork sanction and pipe with some force into the seal and there you have it! a £2.99 fork seal driver!




Followed by the retaining clip and dust seal. I made sure a slight smear of fork oil was between the seal and sanction for easy gliding.



Now as the manual states, I made sure there was atleast 12mm of thread showing above the rod nut on the damper rod.



Now in goes the fork oil, pump the sanction at least 10 times, followed my pumping the damper rod at least 10 times again, then measure 150mm from the top of the fork sanction, with the fork sanction and damper rod fully compressed. I used a turkey baster marked with some tape at 150mm from the tip, makes it SO much easier then using a tape measure and tipping some out!

Then in goes the rebound rod, spring, and washer, followed by the top cap. Make sure you keep that 12mm thread above the rod nut!



Now for resembling the bike and getting out onto the road!
All easy enough apart from the fork height above the top yolk, unfortunately, the clutch cable isn't allowing me to pull them through by the 25-30mm to accommodate for the height difference in forks (see earlier in the thread).
Easily fixed at the end of the day by getting a new clutch cable without the metal curved tube and rerouting it.



Forks in first, nip up the pinch bolts on the yolks, then put the wheel back on with the speedo drive, make sure everything sits straight, then tighten the pinch bolts up to spec.



Then the fender and brakes.



This is where I started to realized how awesome that satin black looks on the forks!

Now then, the ride....

WHAT a difference! No more diving like a sub under heavy braking and the initial turn into corners really gives confidence! The brakes feel more responsive as well without the weight of myself and the bike being thrown onto them.

Admittedly, the ride isn't as comfy as before, it's not full on rock hard, more like a stiff suspension feel, but its a sacrifice for awesome road handling!

I'm incredibly happy with the way the front end has been transformed to a proper confidence inspiring bike!





PROS

- Better road handling

- Better feel to the brakes

- Cheap

- Uses SV wheel, brakes, fork legs, fender and triple clamps

- Looks standard (possible con?)

- Easy project

- End up with something fairly unique

CONS

- Have to drill out the bottom of the SV fork leg to accommodate ZX6R damper bolt.

- New clutch cable if you're working with bars instead of clipons

- Difficult to find a clean, unscathed, cheap pair of ZX6R F1-3 forks

- Emulators and k-tech springs can cost a similar price (depending of cost of ZX6R forks and drilling)

If I ever find that the front end is being a little stiff, I may change the fork oil to 5W to see if that helps at all.

If I can find my old camcorder mount, i'll upload some road footage of the new forks in action with a review included at a later date.


Many thanks to all who have helped, advised and guided me through this little project.

The next stage will be to sort out that clutch cable and get a 636 shock on the rear.

Any questions are more than welcome if anyone has and queries or thinking of doing something similar.

[Bibio]

Originally Posted by Mikey360

So, all the rebound problems have been solved!
Turns out, pouring fork oil directly into the damping rod really stiffens it up!

nowt to do with it. it was as Sid said, the rod needle was seated wrong so was not opening. your damper rod is always filled with oil. 10wt oil is not a good idea in cartridge type forks as it makes them to slow.

[Sid Squid]

Originally Posted by Bibio

the rod needle was seated wrong so was not opening. your damper rod is always filled with oil.

My thoughts exactly. Adjuster setting on the rod is critical.

Originally Posted by Bibio

10wt oil is not a good idea in cartridge type forks as it makes them to slow.

Ordinarily I would agree, but 10 weight is standard for the F and G model forks, and when working right it is excellent suspension even by more modern standards.

[aesmith]

Originally Posted by Mikey360

WHAT a difference! No more diving like a sub under heavy braking and the initial turn into corners really gives confidence! The brakes feel more responsive as well without the weight of myself and the bike being thrown onto them.

Actually I'm pretty sure that your modifications mean that more weight is thrown onto the front wheel under braking. My take on the standard setup is that when the brakes dive you don't get the full weight on the tyre during the time that the suspension is compressing. Then when it is compressed the lower centre of gravity means less weight transfer for the same deceleration.

I'm sure someone could explain that better.

[yorkie_chris]

Your weight is still being pushed onto them, that's just weight transfer under braking which is unavoidable. What you're seeing is the dynamic difference between them pushing down slowly versus collapsing then coming to a rapid halt.


Re adjuster, it's all shown in the feel of what the rebound adjuster does. Think about what's going on with the parts moving or being adjusted in relation to each other.

[jambo]

Originally Posted by Mikey360

If I ever find that the front end is being a little stiff, I may change the fork oil to 5W to see if that helps at all.

If the fork oil in there suits then job jobbed, if it all feels a bit too stiff it may be worth checking out this table of fork oil viscosities. Castrol Synthetic 10w is at the thicker end of the spectrum, so if you change you may end up going with a thinner oil that's still a 10w, but a little closer to the standard Kawasaki / Suzuki numbers. This is probably getting fussy at this point but if you decide to change the oil it's worth having a little read just to make sure you're moving by the amount you think you are if you have to change brands.

Glad it's all worked out

Jambo

In regards to the rebound probelms being sorted, it just seemed odd that when I purposefully dodged filling the rod with oil, it worked properly. When I took the cartridge unit out of the un-rebounding fork, pumping the oil out of it was a real bugger to do, took a lot of strength and effort to get all the oil out of it.
Just a point in case anyone has a similar problem in the future, I'm certain the rebound adjustment rod and top cap adjustment being setup properly the second time made a huge difference

I have a feeling I will be swapping over to 5W in the near future to regain some softer compression and adjust the rebound accordingly, I found that a few bumps on the A43 today where a heck of a lot more abrupt than I expected. I had a feeling this would happen, as many of you advised.

I've never used any sort of 5W before, can someone recommend me a brand/type etc?

[yorkie_chris]

That rod is just a rod with a needle on the end of it inside a pipe... seats into valve seat at back of rebound piston to control oil bypassing rebound piston and shims... there is nothing moving in there to hydraulicly lock... it is totally normal to pump cartridge and have oil running out of the top of the rod when the adjuster rod+needle is not fitted. then you fit needle and rod... i.e totally brimmed full. In use some small amount oil will circulate and leak around here too.