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Discussion Starter · #1 ·
I installed these on my track Ninja 400.

I have Bitubo suspension on another of my bikes and I really like it, so i thought I would give these a try.

There is no modification needed to the fork tube to install these cartridges. There is no need to remove the OEM oil lock on the bottom of the tube.

I used 2.5wt oil as it is equivalent to the recommended oil that we cant get in the US anymore.

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I used SKF seals. They need the plastic spacer washer that comes in the kit.

I also used Racetech superslick bushings. The suspension has very little stiction.

I weigh around 180 lb (a little less) and the stock springs of 0.7 kg/mm are spot on for the recommended rider sag of 35-40mm.

This sounds soft, but you get great feel out of the front. The adjustment for Compression and Rebound adjustments actually make a difference.

I'm excited to get this bike on the track.

I paired the forks carts with the GSXR shock.
 

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Discussion Starter · #2 · (Edited)
If you've ever rebuilt forks before, this is very straight forward and simple to do.

You WILL need to heat the forks around the seal area to get those ******* seals and bushings out. Don't think about reusing them. I about gave myself tendonitis trying to take the one leg apart before I busted out the MAP torch.

I also bought a slim set of wrenches to use on the cap. Its always a tight fit with regular wrenches.

My savior:
Cylinder Gas


Cartridge sticking out through unmodified bottom of fork leg.
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Discussion Starter · #7 ·
@falcn why did you change the seals? Was it about time for new ones anyway? When I put my cartridges in the bike had only 400 miles so I didn't feel the need to change them. Now I'm at about 2300 miles and the stock seals are still working fine, no leaks. A friend of mine put SKF seals on his and they started leaking a bit right away. I've heard the tubes on this bike are a PITA to take apart. I'll probably do all of that in the off-season.
1) I wanted SKF low friction seals vs the stock ones. I have them on other bikes and have not had problems with leaking.

2) After heating the forks to get the seals out - they were done. I typically do not reuse seals anyway when rebuilding my forks, its just not worth it to me.

You are right, I could have just left the lower legs together and dropped in the cartridges, but if I am taking out the guts, I am cleaning and inspecting everything. I got this bike used after it had a drop, and I wanted to check the tubes for straightness. It has 5000 miles on it and I also wanted to replace the bushings. This way I know where I am starting at on the front end.
 

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Discussion Starter · #9 · (Edited)
How much $ does this set up cost? My Ohlins was pricey, it also requires "special" Ohlins brand light weight fork oil but uses it for dampening unlike the Bitumo's, then they also stick you for their spring too. The system works very well and should for the cost..
They were on sale for $485 from Superbike-Unlimited. I couldn't pass that up. Especially after reading some positive reviews, and my own experience with other Bitubo products. That deal might be over now though. It was a manufacturers rebate offered at the time. I should have posted it here, didn't think about it. They were originally $570 with ~85 factory discount added.

They are still "on sale", just at a little higher price:

Add price in for the lightweight fork oil of course, but you need fork oil for any fork rebuild. I happen to like Motul fluids. It only took 1 bottle for both legs. You have a low oil height, 150mm from the top of the fork tube when collapsed, so it doesn't take much oil.

I bought two bottles, two sets of seals and two sets of bushings. I don't like having to wait for parts when I need to do a rebuild down the line, but that is just me.

The SKF seals were about $36 for one set, so you need two [email protected]$72

If you can't do the work yourself, its shop rate for installation. I do all my own work on my bikes, forks, valves, tire changes, etc. etc. Only thing I won't be doing is servicing the shock and fork cartridges when they need it.

The Racetech Superslick bushings are $22 FMBO41152P Outer and $25 FMBI41201P Inner for two of each in a package (enough for both legs).
 

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Discussion Starter · #11 ·
Ok that makes sense. I never took mine apart, just put the cartridges in. I'll do that after this season hopefully. Although I think I have brand new seals that I bought from Norton when I first got my bike, just in case I needed them. Not sure what brand they are but pretty sure it's something else.
Probably stock or All Balls. They're not bad. **** I am not even racing, just doing track days. I just did it because.

When I tested my sag with this set-up: Low Friction SKF seals and Racetech Bushings, I have very little stiction difference in the pull/settle and push/settle static sag and rider sag.
 

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Discussion Starter · #12 ·
It's because they're gas charged forks. So the oil is just on the outside of the cartridge and only needed to lubricated the inside, hence you also don't need to use much. It's not oil used for damping like in more traditional setups. I like mine, only downside is I don't have the equipment to work on the cartridge so I have to send it out to someone that specializes in these. I actually went up a spring size over the winter in mine and I have 0.9 kg/mm springs and I like it better because the front end doesn't dive as much on the brakes.
That's up quite a few from the stock 0.7 kg/mm - how much do you weigh? How may turns of preload are you running with that? 5/10?
But yeah, it all depends on the rider, what they like for pre-load and brake dive. I might hate it after my first sessions and want to go up a rate or two. We'll see.
 

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Discussion Starter · #15 ·
Interesting technology! They say the faster you get the stiffer you need to go on your spring rates so that's a good sign for you. With my light weight I found the stock .77's were OK at the track but if I was fully racing I'd probably go to .80's or .85
What is really cool is the ability to revalve without taking the forks apart. If you have the tools and the parts from Bitubo you can change spring rates and valving for rebound or compression with the bike up on the front pin stand. I won't be taking advantage of that, but it is neat. Of course the spring replacement is easy and doesn't require you to disassemble the forks on most bikes.
 
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Discussion Starter · #17 ·
Loving the suspension after my two track school days. The kart track is anything but smooth, and these cartridges give me confidence in my front end since I can feel what is happening. Feedback/feel is awesome. Haven't had to make any adjustments yet to compression or rebound from factory recommended settings for my weight.
 

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Discussion Starter · #19 ·
I might go heavier on the front springs at this point.

Still loving the suspension. .85 might be my next try if I can source them.
19667
 

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Discussion Starter · #21 ·
Mine came with 0.7 and I am definitely stuffing fully on end of straight braking.

I didn't see this post before ordering the 0.85 from SuperBike Unlimited.

Thanks for the offer!
 

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Discussion Starter · #23 ·
Finally!!! Got the 0.85 springs from Italy...jeebus that took forever. Track day coming up on Oct 11th.
New SBS DC brake pads installed on the front Brembo caliper.
I am LOVING THIS THING on the track.
 
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Discussion Starter · #25 ·
Yah, I didn't expect it to take THAT LONG. geez.
Result - felt better going into hard braking, but I need to play with my rebound and compression again. Might start over with factory settings. Was feeling a little off after the change.
 

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Discussion Starter · #34 · (Edited)
No modifications are needed to the stock fork internals with the Bitubo cartridges. The instructions are pretty clear when you buy them.

INSTRUCTIONS on this page

You do reuse the top out springs, but they just come out.

Bitubo recommends servicing every 2 years of use or 20,000km.
 
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