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Discussion Starter · #1 ·
My son has been riding his 400 but so far just a handful of times and I have been making mods along the way. Then when we got his race license and were getting ready to focus on the 400 he broke his hand trying to avoid a motorcycle that went down in front of him at the Motoamerica Mini Cup race at the Ridge. His hand got stuck somehow around the swingarm or wheel but, it's not a bad break and hopefully he'll be back soon. Right now I'm taking the time to get as much done as I can before his first race on the 400 at Pitt Race in August then trying to figure out what I'm going to upgrade next. So far here's what i've done.

  • Sprung the ohlins rear shock that came with the bike, a 2018 used ABS model with a spring for an 80lb kid. Previously sprung for a 240lb man and he said he could feel every pebble!
  • Installed Andreani fork cartridges with the correct spring rate for his weight
  • Changed the geometry of the bike raising it 10mm in the rear and dropping it 35mm in the front. Now it turns effortlessly. Before it would fight to stand back up.
  • Had preload and baseline suspensions settings setup by MRP Motorsports.
  • Changed the stock setup to GP shift which my son is used to
  • Installed Norton rear set risers. A little cheaper then rear sets and I didn't need much adjustability with my son being 4'8 the main thing was as high up as they could go.
  • Installed Spiegler Stainless steel brake lines front and back and Vesrah XX pads
  • Installed Spears Velocity Stacks
  • Installed full Akra Exhaust
  • Installed Spears racing Flashed ECU
  • Changed out the street bodywork for hotbodies track fairings
  • Installed a 520 non o-ring lightweight chain and lightweight aluminum sprockets but I was not getting the reduced rolling resistance I wanted.
  • Installed a 415 non o-ring dirt bike DID chain and lightweight aluminum sprockets. Hoping I get some longevity but I'm not counting on it. It has however reduced the amount of roll resistance the 520 chain had by doubled the amount.
  • Installed TST Captive Chain tensioners.
  • Installed the Dunlop Motoamerica Spec Race tires. My son raced one day(His first day on the 400) on Q3+'s and didn't really like them very much. They were just not at the level of grip and feedback that he was used to on his Ohalve but they are probably fine tires but I didn't see the need to spend time learning them when slicks are cheap for the 400.
  • Installed Shogun Frame Sliders
  • removed the fan
  • installed a thermal heat shield above the radiator
  • Installed a Motion Pro quick turn throttle.
  • I have block off plates on the way
  • Checked the ergonomics of the bike and I thought the stock clip on's would be terrible but they aren't for my sons size. Anything bigger and he'd have to reach too far and smaller his body wouldn't be in the right position. Maybe I will get clipon's in a similar spec to the stock clip on's just so I have spares going forward that are easy to change at the track.

Now I am at a point where we've made significant changes like the ECU, Velocity Stacks, Full Exhaust, 415 chain but since he's injured we haven't been able to test anything and right now his schedule to return is of August but we signed up for a race the week before hoping it would be healed. So I think I know how it's going to perform but it's hard to tell. I can say that the throttle seems so much more responsive and less sluggish than before.

Trying to decide what to do next. I know the clutch needs to be upgraded it slips quite a bit. I want to do more for the front brake like a brake tech rotor. I should paint the bike, it's just primer gray right now. I want to get actual rear sets instead of risers and and replace the stock clip on's as well. Maybe best thing is to just see how all these parts work together at his next race in August and then go from there. If I missed anything happy to hear suggestions.


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I’d buy a case of those 415 chains. Being small and light it may last longer for your son but larger riders around here replace them for every race because they break.
 

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Discussion Starter · #3 ·
Yeah I'm planning to buy spares and I expect to have to be really diligent keeping them clean and making sure the tension is right and they are lubed. It seemed like a huge improvement in resistance compared to the 520 so I'm excited to see if it helps on the track at all.
 

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Discussion Starter · #5 ·
Sounds like an awesome build so far, looking forward to seeing how you perform. The clutch is terrible on the 400, so many issues. The false neutrals and drop from 5th to 4th is so annoying. I'd highly suggest the Norton race upgrade, since it'll fix the majority of issues for a really good price. Ninja400R Race Spec Clutch Upgrade Kit - Kawasaki Ninja 400 / Z400
Thanks, definitely need to upgrade the clutch. I will look into the Norton race upgrade for sure. Chris was just cleared from his broken arm to race today so we're going to do the next CCS race at NC Bike in a few weeks so we'll get to test everything we put together for the first time. Looking forward to seeing how everything works together. Unfortunately he's never been to NC Bike before and I think there's just two practice sessions before the races so he'll be learning the track on the fly but that's ok. Just want to get some experience in the first race.
 

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Sounds like an awesome build so far, looking forward to seeing how you perform. The clutch is terrible on the 400, so many issues. The false neutrals and drop from 5th to 4th is so annoying. I'd highly suggest the Norton race upgrade, since it'll fix the majority of issues for a really good price. Ninja400R Race Spec Clutch Upgrade Kit - Kawasaki Ninja 400 / Z400
No. Actually it doesn’t. In my case anyway. The clutch really has nothing to do with the trans/shifting problems but I’ve done all the Norton mods and mine is still worse than my sons which is stock. I think the machine works on the gear dogs is hit or miss on these gear boxes.
 

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Discussion Starter · #7 ·
No. Actually it doesn’t. In my case anyway. The clutch really has nothing to do with the trans/shifting problems but I’ve done all the Norton mods and mine is still worse than my sons which is stock. I think the machine works on the gear dogs is hit or miss on these gear boxes.
Oh wow so the Norton mods didn't fix the issues? I thought Norton and Spears had this figured out and I was going to go with one of their kits.
 

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Oh wow so the Norton mods didn't fix the issues? I thought Norton and Spears had this figured out and I was going to go with one of their kits.
They can help. But they don’t fix the real problem with the infamous 5th-4’th-5’th auto gear change. Only under cutting the gear dogs that they can also do will actually fix it.
 

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Discussion Starter · #9 ·
They can help. But they don’t fix the real problem with the infamous 5th-4’th-5’th auto gear change. Only under cutting the gear dogs that they can also do will actually fix it.
I see thanks. I was hoping to not have to undercut the gears but good to know
 

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They can help. But they don’t fix the real problem with the infamous 5th-4’th-5’th auto gear change. Only under cutting the gear dogs that they can also do will actually fix it.
Yes, you have to get the undercut shift star as well. I'm very surprised that the blueprinted shaft and race clutch pack didn't help. It's really bad on my stock 400, and the ones that have the upgraded Norton clutch components never have this issue from what I've seen. I was just out at MotoAmerica this last week working on the Altus 400 which had the blueprinted shaft, undercut transmission, and was shimmed the same thickness as the Norton clutch pack.
 

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I have the undercut shift star and the ‘blueprinted ‘ shift shaft. The shift shaft is a joke. I can do the same thing in 3 minutes to one with a hammer and punch. ;)
 

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They can help. But they don’t fix the real problem with the infamous 5th-4’th-5’th auto gear change. Only under cutting the gear dogs that they can also do will actually fix it.
^Yeah, what he said.

I see thanks. I was hoping to not have to undercut the gears but good to know
Not all 400s suffer from it as bad. Some are definitely worse than others. @jetpilot01 has seen or owned a couple of them that were very severe where it was popping out of 5th gear a LOT. Others don't have it as much. I haven't undercut mine, and it pops out of 5th gear maybe once per weekend, if that. I was at Jennings yesterday for example and it never popped out at all. The biggest thing I found that helps is to be firm with your foot when shifting, and setting the timing on the quickshifter well enough. I think mine is set somewhere around 65-70 ms. If you go shorter, it'll be more prone to have that issue.

I have the undercut shift star and the ‘blueprinted ‘ shift shaft. The shift shaft is a joke. I can do the same thing in 3 minutes to one with a hammer and punch. ;)
I regret getting the blueprinted shaft. Didn't notice any difference. Hasn't helped at all, and to be honest I couldn't even tell any difference at all. For all I know, they sent it right back the way it was lol Waste of $130 or whatever it was.
 

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I'll have to give that a try. It didn't over flare them or crack them?
Now that I know that you know what I’m talking about, yes you have to be careful. :)

I used an impact socket sized to support the back side of the rivet to take the load off the fork and carefully worked it down until the wobble in the fork is gone. If you go too far and get it too tight trying to spread it open again is when you may crack it. After getting the Norton piece I experimented with my stock.

But honestly if you really look at it and the play isn’t enough that it misses the shift star it doesn’t make a lot of difference. Undercutting the gears, unfortunately, is the fix. :(
 

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Now that I know that you know what I’m talking about, yes you have to be careful. :)

I used an impact socket sized to support the back side of the rivet to take the load off the fork and carefully worked it down until the wobble in the fork is gone. If you go too far and get it too tight trying to spread it open again is when you may crack it. After getting the Norton piece I experimented with my stock.

But honestly if you really look at it and the play isn’t enough that it misses the shift star it doesn’t make a lot of difference. Undercutting the gears, unfortunately, is the fix. :(
I'll probably buy a spare shaft just so I can do it on the bench and have one I know works. It'll be interesting so see. Mine is definitely much worse than the blueprinted one on the Altus bike. I need to get the shift star undercut, see if that helps but I'll likely end up undercutting the transmission. Been focused on suspension so far, once I have cartridge inserts I'll start delving deeper into the engine.
 

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The shift star did make the shifts seem faster and more tight in all but that **** 5’th. It will still do that **** 5-4-5 thing a couple of times in a race.

But like I said, my son’s only has the shift detent spring and doesn’t f up nearly as much as mine. Go figure. :)
 

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The shift star did make the shifts seem faster and more tight in all but that ** 5’th. It will still do that ** 5-4-5 thing a couple of times in a race.

But like I said, my son’s only has the shift detent spring and doesn’t f up nearly as much as mine. Go figure. :)
My advice...when he's not looking, swap out the bodywork and any obvious parts between the bikes :p
 
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