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Discussion Starter #1
So, I’ve been working on this much slower than I’ve wanted to, and I think I’m finally to a point where I’m going to post about it. I’d say the swing arm is about 95% complete, and the triple tree is about 50%. All of the parts have come from a 2016 ZX6R. Pardon the messy garage in the pics, I’ve had a lot of life things going on lately.

Done so far:
Swing Arm:
-Cut arm and added bushings to attach to stock 400’s pivot
-Used shock from 600/750 GSXR, slightly modified the mounting point on swing arm to account for the ZX6R’s offset in suspension
-Used 3/8” offset front sprocket to align the sprockets/chain
-Moved a few lines/wires, added spacer for right rearset to clear master cylinder

Forks:
-Mock installed triple tree

Left to do:
Rearset:
-Fine tune a few things, get ride height correct after front forks are done.

Forks:
-Get risers for controls and install. There is absolutely NO way the ZX6R’s setup will fit with the 400’s plastics
-Install bearings to fit the triple tree to the head.
-Fabricate new steering stop. I feel this is relatively minor, yet necessary.
-Rewire/Recable as necessary.

Honestly, this has been a lot of fun. I 100% do not recommend the swing arm though. The amount of burden it has been to make it work is absurd, and there are probably better options out there. As for the forks, I’m pretty excited to see how this is going to pan out.

Oh, and one more thing. I am very very aware that I could have sold my 400 and taken the money I’ve dumped into this and picked up a nice new ZX6R, but what’s the fun in that?
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Seems like a lot of work and a lot of unnecessary extra weight that is added. What’s the goal you are trying to achieve with this suspension swap?
 

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Discussion Starter #3
Seems like a lot of work and a lot of unnecessary extra weight that is added. What’s the goal you are trying to achieve with this suspension swap?
The main reason is “Because I could.” I didn’t put it on a scale, but I will say that the swing arm is incredibly light, possibly even less than stock. Over all, I don’t think there is much of a gain in total weight. If that concerned me, the best weight reduction I could do is get myself down to a decent body weight.

In all seriousness, the stock front suspension leaves a lot to be desired. I am personally a fan of upside down forks. I’ve also never been particularly pleased with the breaking power, even with ABS. This checked all of those boxes (well... the rear brake is smaller on the ZX6R... weird, right?). I had originally thought about taking the 650’s suspension and brakes, but this seemed better over all.
 

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not to hijack but has anyone looked at 390 front end and swap out the OEM 390 stem for an N4 OEM stem? USD forks on the 390 with a radial brake caliper plus 110 rim
 

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not to hijack but has anyone looked at 390 front end and swap out the OEM 390 stem for an N4 OEM stem? USD forks on the 390 with a radial brake caliper plus 110 rim
Or latest model R3 front end. A guy here races both bikes and says front end on the R3 is superior to the KTM.
 

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Discussion Starter #9
I took it out for a test ride today, so here is where I am with this so far.
The steering stem was a mess, as expected. I chose to modify the bearings since I couldn’t find any bearings that had the correct id/od without getting something custom made that was severely cost inhibitive. The handlebars suck, a lot. I wasn’t sure what I was getting into, so I got a few cheap clamps off ebay. I believe the correct ones to use will be Woodcraft’s 50mm 1.5” or 2“ risers. This should give me back the height I lost in the front by being able to place them under the top triple clamp. Wheel speed sensors are a mess, I have no idea why they’re not working and I have put zero time into investigating it yet. All in all though, despite the geometry being in a weird spot right now, the fork swap made a word of difference in the front, and the front brakes perform great.
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Discussion Starter #11
It’s been a bit, but here is where I am with this. I went with a set of Woodcraft 2” riser clipons. That let me bring the front of the bike back up to a normal height. The electronic controls are still stock 400, the levers are ZX6R. At some point I am going to have to do something about the front brake. It sits at an awkward angle, still very usable though. There may be some modification to the plastics somewhere down the road. The steering stop is figured out, I just need to get in there and trim down the stop on the frame. A big issue of the ABS was fixed by simply reversing the polarity of the wires on the sensors, I highly recommend reading wiring diagrams instead of assuming that they kept the colors the same (to be fair, they both were green...). I have some more exploring of the ECU to do to see if I can find CANBUS lines anywhere. I know the diagnostic port only supports KWP2000, so next time I dig the ECU out, I’ll crack it open and see the chips give me any clues. Reason for that being the potential to get the KIBS working from on the ZX6R’s ABS unit. Overall, I am happy with it, despite my complaints and saying if I had it to do over, I wouldn’t. Next is definitely a steering damper, maybe change some of the linkages to drop the tail a little, and see if I can do about the crappy rear brake this thing has. Here are a few pics.
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Discussion Starter #13
After today, I take back every single negative thing I have ever said about this project. I have been fighting this weird feeling when cornering, almost like a wobble, but it tries to stand the bike up, so you’re fighting it to lean deeper. After trying, checking, and rethinking everything I could, I just accepted that widening the linkages and slightly raising the tail was having an affect I couldn’t quite explain, but knew was there. (Must have been the geometry and inconsistent tire wear between the front and rear, amirite?) Now, I am not an advanced rider by any means, have zero track time, and don’t have any local resources that I know well enough to drag into this mess, so I’m sure all of you who read this are going to get a kick out me discovering something painfully obvious. I had been running 28 and 32psi in the tires, just like you would on a stock 400. Today was a lazy day, so a nice ride was in order, no tuning, no adjustments, just a nice easy ride. I decided to adjust the tire pressure to what ZX6R group is running, which is 36 and 42psi. I took off and noticed a world of difference, it has never handled this well since the swap. So, I hope everyone had a good chuckle at this, because even now I’m still baffled that this never occurred to me.
 

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This is a totally awesome build! (y) Butt, I think your PSIs should be close to, or at a stock N400. The ZX6 runs higher PSIs, cuz it's heavier, 'n heavier bikes need more PSI to keep the tires from "deflecting."Or if yer a big dude ya might wanta run higher PSIs?
Dunno where you are butt GMD Computrack can fix geometry issues. Or a cheaper easier fix might be to find a stock N400, 'n take measurements to get yer bike close to the stock geometry.
Good luck with this, 'n keep us posted. :D
 

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After today, I take back every single negative thing I have ever said about this project. I have been fighting this weird feeling when cornering, almost like a wobble, but it tries to stand the bike up, so you’re fighting it to lean deeper. After trying, checking, and rethinking everything I could, I just accepted that widening the linkages and slightly raising the tail was having an affect I couldn’t quite explain, but knew was there. (Must have been the geometry and inconsistent tire wear between the front and rear, amirite?) Now, I am not an advanced rider by any means, have zero track time, and don’t have any local resources that I know well enough to drag into this mess, so I’m sure all of you who read this are going to get a kick out me discovering something painfully obvious. I had been running 28 and 32psi in the tires, just like you would on a stock 400. Today was a lazy day, so a nice ride was in order, no tuning, no adjustments, just a nice easy ride. I decided to adjust the tire pressure to what ZX6R group is running, which is 36 and 42psi. I took off and noticed a world of difference, it has never handled this well since the swap. So, I hope everyone had a good chuckle at this, because even now I’m still baffled that this never occurred to me.
Awesome!! Very cool....
I am not sure how I missed this up until now......I commend you for doing this and getting it done. Great job!

For sure......tire pressure, that probably would have eluded me as well at first.......hard to say.....it seems like at times I have a blank stare moment, and other times I totally plan for it ahead of time, and catch it before first ride........

If you are running the tires and wheels off the 6R that would make sense......even though the weight of the rest of the bike is a little different......still the wider wheels, tires, swingarm and weight of wheels and tires, etc......unsprung weight of wheels, tires, rotors, etc. would all be the same as the 6R........

Also would you say its easily the same as it was OEM, flick-ability and agile wise?
Not sluggish any? I know its hard to compare superior forks and shocks..but overall would you say its just as agile and light?
 

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Discussion Starter #17
Also would you say its easily the same as it was OEM, flick-ability and agile wise?
Not sluggish any? I know its hard to compare superior forks and shocks..but overall would you say its just as agile and light?
Thanks! It’s been quite an experience. As far as agility, I would say that it might be ever so slightly more cumbersome, but cornering and leaning feels much more deliberate. The swap on the front put it much more on par with the rear, which the factory forks being so noticeably squishy after the rear shock swap (factory swing arm) was a big motivation to get something done on the front. I’m not cornering at track speed or angle either, but to be honest, I feel more comfortable leaning deeper with this setup. There is also a huge margin of error for placebo affect here.
I don’t feel like I picked up much, if any, weight. The swing arm is incredibly light, which might help to balance out the added weight from everything else. I don’t notice it being any more sluggish that I would expect, especially with the consideration of my gearing is 15/40. I also have a tuning issue in the low end that I need to work out, it is going VERY rich (like 8-9:1 on pump gas). It’s explainable because I have the MAP sensor bridged onto both throttle bodies, so the readings are very different than what it would expect to see at that RPM. Once it gets into the range where I have it tuned well, it’s all good, no noticable drop on the butt dyno, and maneuverability is still great.

I’d say the most surprising thing to come out of all is the speedometer is dead on, better than it was from the factory.
 

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So, I’ve been working on this much slower than I’ve wanted to, and I think I’m finally to a point where I’m going to post about it. I’d say the swing arm is about 95% complete, and the triple tree is about 50%. All of the parts have come from a 2016 ZX6R. Pardon the messy garage in the pics, I’ve had a lot of life things going on lately.

Done so far:
Swing Arm:
-Cut arm and added bushings to attach to stock 400’s pivot
-Used shock from 600/750 GSXR, slightly modified the mounting point on swing arm to account for the ZX6R’s offset in suspension
-Used 3/8” offset front sprocket to align the sprockets/chain
-Moved a few lines/wires, added spacer for right rearset to clear master cylinder

Forks:
-Mock installed triple tree

Left to do:
Rearset:
-Fine tune a few things, get ride height correct after front forks are done.

Forks:
-Get risers for controls and install. There is absolutely NO way the ZX6R’s setup will fit with the 400’s plastics
-Install bearings to fit the triple tree to the head.
-Fabricate new steering stop. I feel this is relatively minor, yet necessary.
-Rewire/Recable as necessary.

Honestly, this has been a lot of fun. I 100% do not recommend the swing arm though. The amount of burden it has been to make it work is absurd, and there are probably better options out there. As for the forks, I’m pretty excited to see how this is going to pan out.

Oh, and one more thing. I am very very aware that I could have sold my 400 and taken the money I’ve dumped into this and picked up a nice new ZX6R, but what’s the fun in that?
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man, i absolutely love your project !!!
 
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