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Discussion Starter · #1 · (Edited)
As many of you know, the front suspension on the Ninja can feel a bit like a pogo stick at times. I'm not sure if this is because my fork oil is degraded but it's an issue I want to address. I'm also hoping to make the bike feel more 'planted' through corners, particularly on bumpy rural roads.

I went to see a mechanic to get my 12k Km service done booked in and raised the above points to which he suggested the below products. It'll cost roughly $2.9k NZD installed which I think is a fair price.

REAR SHOCK BITUBO XXT11

Bitubo JBH0 Pressurized Fork Cartridge Kit

I'm not sure if they're a bit overkill, but I'm primarily a weekend warrior and interested in attending a couple of track days this year. What do you guys reckon? Would it be better to just fry replacing the fork oil?

Has anyone else who primarily uses their bike on the street done similar work like this?

Also, if it helps I'm roughly 57 Kg (125 pounds)
 

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As many of you know, the front suspension on the Ninja can feel a bit like a pogo stick at times. I'm not sure if this is because my fork oil is degraded but it's an issue I want to address. I'm also hoping to make the bike feel more 'planted' through corners, particularly on bumpy rural roads.

I went to see a mechanic to get my 12k Km service done booked in and raised the above points to which he suggested the below products. It'll cost roughly $2.9k NZD installed which I think is a fair price.

REAR SHOCK BITUBO XXT11

Bitubo JBH0 Pressurized Fork Cartridge Kit

I'm not sure if they're a bit overkill, but I'm primarily a weekend warrior and interested in attending a couple of track days this year. What do you guys reckon? Would it be better to just fry replacing the fork oil?

Has anyone else who primarily uses their bike on the street done similar work like this?

Also, if it helps I'm roughly 57 Kg (125 pounds)
I have Bitubo suspension on my 400, but it's a race bike. It's definitely good stuff, but also definitely overkill for street riding and a couple of track days. There are cheaper upgrades available that will be a better bang for the buck. Traxxion Dynamics AR25 kit for the forks and getting a GSXR shock will get you a much better planted bike for about 1/3 of the cost or less. I used to have the AR25 fork kit and an Ohlins shock at first and it was plenty good even for racing, I just wanted something a bit better.
 

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I think the Ninja's suspension is probably set for someone in the 70kg to 80kg range standard. Have a look around the site, as there are other options such as replacement springs etc. I do all my riding on the road, and haven't had to change anything on my Ninja (I'm about 72kg).

The cost your mechanic has given you seem pretty reasonable for supply and fitting, but like sbk1198, it's probably a bit too much for a non track bike.
 

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I just did the currency conversion and holy crap that's a lot of money!! That comes out to be right around $2000 USD. Here you can buy that shock and fork cartridges brand new for $1400-$1500. I bought mine used for $1000. I would never spend that much money if it was mostly a street bike, but if you don't mind spending the money, then by all means.
 

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Discussion Starter · #5 ·
Thanks both.

@sbk1198 yeah mate it's not cheap. I think the remainder of the $2k is for labour and parts.

Do you think I could expect a more steady front end if I get the fork oil changed? Perhaps to a heavier weight?

My dilemma right now is whether I upgrade the ninja and hold onto her for a few years vs maybe buying a higher spec bike like the R7 or ZX6R.
 

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How old is your bike? And you might want a lighter oil with a different spring. You have to remember that the 400 is built to a price, and it's a great bike for what it is.

Suspension is a bit of an art. If you really want to upgrade maybe have a chat to a suspension expert. I'm sure that they'll be happy to give you a range of options.
 

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Discussion Starter · #7 · (Edited)
It's a 2020 model with 11ish Kms on the clock.

The mechanic who suggested this setup is a suspension tuning guru and has a bit of a cult following amongst local racers.

I'll raise the idea of changing springs/oil weight with him. I think his rationale for suggesting the Bitubo parts is that they'll enable adjustability which he can then use to make the bike 'fit' me better.

I'll post a quick video when I get home to show my front fork compression. It definitely has a secondary bounce when pushed, unsure if theres a technical term for this. Maybe someone here can let me know how it compares to their bike.

Edit: Video attached

 

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Thanks both.

@sbk1198 yeah mate it's not cheap. I think the remainder of the $2k is for labour and parts.

Do you think I could expect a more steady front end if I get the fork oil changed? Perhaps to a heavier weight?

My dilemma right now is whether I upgrade the ninja and hold onto her for a few years vs maybe buying a higher spec bike like the R7 or ZX6R.
Ahh ok that makes sense then if you're having him install it. Swapping a shock is easy. It's only 2 bolts. The fork cartridges is a bit more involved, but with the Bitubo you don't need any special tools. If you have a set of wrenches and Allen wrenches/hex bits and a vise you're good to go. You can save a lot of money by doing your own work, but I understand it's not for everyone and some people don't have the means to do it.

Changing the fork oil to a different viscosity will certainly affect the damping of the forks, but there's no saying in how exactly. You could make it better or worse. Or you might make one characteristic better (say for example how it dives under hard braking) but make something else worse (like how it absorbs bumps when cruising). There are a few variables that play into it. Kinda depends on what you're looking for too.
 

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Discussion Starter · #9 ·
I'm comfortable tackling basic maintenance tasks but forks are a bit beyond my skill right now.

Given all the variables involved and work required to re-jig the set up and the risk of making things worse, I'm actually leaning towards the Bitubo parts.

By the way, does my front end look normal in that video? I'm trying not to add any additional force after the first push.
 

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I'm comfortable tackling basic maintenance tasks but forks are a bit beyond my skill right now.

Given all the variables involved and work required to re-jig the set up and the risk of making things worse, I'm actually leaning towards the Bitubo parts.

By the way, does my front end look normal in that video? I'm trying not to add any additional force after the first push.
You're not really pushing very hard on it in that video to see the full travel, but from what you did it looks normal. Not great...but normal for stock forks.
 

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It definitely has a secondary bounce when pushed, unsure if theres a technical term for this.
"Underdamped" means that there is actually a periodic oscillation (i.e., overshoot and return), albeit diminishing, possibly more than once.

"Critically damped" would mean that you get back to your starting position without any overshoot and return -- and any less damping would result in overshoot and return.

"Overdamped" would be any more damping than critically damped (so you get back even slower that you have to, still without any overshoot and return).

I'm pretty sure the last time I looked at my front fork it was just slightly underdamped -- same as I would describe your video.
 

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Discussion Starter · #12 ·
Thanks all, appreciate the replies.

I'm still considering the Bitubo parts. The mechanic implied that the bike would feel more akin to a high spec sport bike, I've never ridden a proper 600/1000 so don't really know the difference. Also need to decide whether I'll hold onto the N400 long term :)
 

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600's are totally different machines. Nothing you will do to a N400 will make it feel like a 600 I4.

I'd ride the N400 as it is for as much as you want and save that money to upgrade to the 600 you like when you're ready for it.
 

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@sbk1198 do you have any experience with their damper?

I'm on the fence with the damper as a whole since I haven't had too many issues with headshake but the bitubo kit looks nice and is reasonable.
 

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@sbk1198 do you have any experience with their damper?

I'm on the fence with the damper as a whole since I haven't had too many issues with headshake but the bitubo kit looks nice and is reasonable.
No. I don't feel the need for a steering damper on a 400. I've only ever used Ohlins dampers on bigger bikes, but on the 400 I just think it's a waste of money.
 
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