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Discussion Starter · #1 ·
I was watching Sportbike Trackgear's video install of the Ninja 400 Yoyodyne clutch. In the video Brian mentioned his son had previously been running EBC 600RR clutch springs for racing. It had strengthened the clutch, but lost slipper effect. A tradeoff I'll take any day.

Anyone tried the same thing? Or does anyone know of tougher springs from another bike that would fit? Stock Ninja 400 springs are 20mm outer diameter, 14.5mm inner diameter, around 42mm long.

I've looked at using washers to preload the existing springs, but the design makes it awkward. The plate at the engine cover end of the spring has protrusions to capture the spring. The pressure plate end of the spring has elongated holes so the slipper clutch can ramp.

I've got the Barnett springs installed, but honestly I'm suspecting they've worn out or something. They've had 24,500km of use. Clutch is slipping in 4th between 8000-10000rpm. Clutch stack height well within spec. Steels are flat and looking good. I've got the adjusted length pull rod, not that it should affect anything yet. Was running on the same synthetic oil for a few thousand k's before it started slipping, the same stuff I've always used. Swapped to mineral to see if any difference, none.

I removed my clutch cable return spring and was surprised how much of a floppy wet noodle the clutch lever was with just the Barnett springs providing resistance. Out of curiosity I swapped the factory springs back (only had 1000km of use) in and could have sworn the lever was stiffer at full pull.

To test out spring compression between Barnett vs stock, I rigged up a bunch of weights on a big car battery, the battery supported at one end by the spring, and measured the compression. I couldn't measure any difference. I think the Barnett springs are said to be 10-15% tougher than stock.
 

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I was watching Sportbike Trackgear's video install of the Ninja 400 Yoyodyne clutch. In the video Brian mentioned his son had previously been running EBC 600RR clutch springs for racing. It had strengthened the clutch, but lost slipper effect. A tradeoff I'll take any day.

Anyone tried the same thing? Or does anyone know of tougher springs from another bike that would fit? Stock Ninja 400 springs are 20mm outer diameter, 14.5mm inner diameter, around 42mm long.

I've looked at using washers to preload the existing springs, but the design makes it awkward. The plate at the engine cover end of the spring has protrusions to capture the spring. The pressure plate end of the spring has elongated holes so the slipper clutch can ramp.

I've got the Barnett springs installed, but honestly I'm suspecting they've worn out or something. They've had 24,500km of use. Clutch is slipping in 4th between 8000-10000rpm. Clutch stack height well within spec. Steels are flat and looking good. I've got the adjusted length pull rod, not that it should affect anything yet. Was running on the same synthetic oil for a few thousand k's before it started slipping, the same stuff I've always used. Swapped to mineral to see if any difference, none.

I removed my clutch cable return spring and was surprised how much of a floppy wet noodle the clutch lever was with just the Barnett springs providing resistance. Out of curiosity I swapped the factory springs back (only had 1000km of use) in and could have sworn the lever was stiffer at full pull.

To test out spring compression between Barnett vs stock, I rigged up a bunch of weights on a big car battery, the battery supported at one end by the spring, and measured the compression. I couldn't measure any difference. I think the Barnett springs are said to be 10-15% tougher than stock.
Funny that you brought up the Barnett spring compression rate. When I put mine in I looked very closely and could see no physical difference. I went as far as compressing the OEM and the Barnett springs alternately with a pair of slip joint pliers. Could not really tell a difference. I figured it was just me. Shrugged my shoulders and put them in.
 

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I was watching Sportbike Trackgear's video install of the Ninja 400 Yoyodyne clutch. In the video Brian mentioned his son had previously been running EBC 600RR clutch springs for racing. It had strengthened the clutch, but lost slipper effect. A tradeoff I'll take any day.

Anyone tried the same thing? Or does anyone know of tougher springs from another bike that would fit? Stock Ninja 400 springs are 20mm outer diameter, 14.5mm inner diameter, around 42mm long.

I've looked at using washers to preload the existing springs, but the design makes it awkward. The plate at the engine cover end of the spring has protrusions to capture the spring. The pressure plate end of the spring has elongated holes so the slipper clutch can ramp.

I've got the Barnett springs installed, but honestly I'm suspecting they've worn out or something. They've had 24,500km of use. Clutch is slipping in 4th between 8000-10000rpm. Clutch stack height well within spec. Steels are flat and looking good. I've got the adjusted length pull rod, not that it should affect anything yet. Was running on the same synthetic oil for a few thousand k's before it started slipping, the same stuff I've always used. Swapped to mineral to see if any difference, none.

I removed my clutch cable return spring and was surprised how much of a floppy wet noodle the clutch lever was with just the Barnett springs providing resistance. Out of curiosity I swapped the factory springs back (only had 1000km of use) in and could have sworn the lever was stiffer at full pull.

To test out spring compression between Barnett vs stock, I rigged up a bunch of weights on a big car battery, the battery supported at one end by the spring, and measured the compression. I couldn't measure any difference. I think the Barnett springs are said to be 10-15% tougher than stock.
I'm pretty sure Barnett has 2 or 3 types of springs for this bike, and one of them is equivalent to stock, but they also have stiffer ones. That's what I've been running for 3 years so far and it's been fine, also noticeably better as in less slip and engages better/quicker. Maybe you don't have the stiffer ones?

Nevertheless, with that much usage (presumably on the same clutch), it's definitely time for a new set of fiber plates. Even if the stack height is within spec, it's still possible that the fiber pads on the plates are just glazed at this point and they don't provide the same amount of friction.
 

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Discussion Starter · #4 · (Edited)
I'm pretty sure Barnett has 2 or 3 types of springs for this bike, and one of them is equivalent to stock, but they also have stiffer ones. That's what I've been running for 3 years so far and it's been fine, also noticeably better as in less slip and engages better/quicker. Maybe you don't have the stiffer ones?

Nevertheless, with that much usage (presumably on the same clutch), it's definitely time for a new set of fiber plates. Even if the stack height is within spec, it's still possible that the fiber pads on the plates are just glazed at this point and they don't provide the same amount of friction.
The Barnett springs were bought from Norton. It was the only Barnett springs they offered, so should be the tough ones.

The clutch fibres and steels currently installed have only done about 5000km. Both replaced when my original clutch started slipping. Incidentally I just noticed the original clutch was also within thickness spec.

One thing I've noticed is that whenever I've looked at the clutch it has been really dry. I found it interesting in the Sportbike Trackgear Yoyodyne vid that Brian mentioned the pull rod should have a bit of slop in its hole because this is the primary oiling source of the clutch. Oil is pushed out around the outside of the pull rode and spun out through the inside of the clutch. He mentioned that if the tolerance is too snug, the clutch wouldn't get much oil and tend to overheat. A fix is dremelling a flat along the pull rod. I'm assuming the Yoyodyne people had told him this.
My pull rod seems rather snug, but I'm a bit loath to grind it.

Makes me wonder though, because my clutch is totally fine in the first 30 minutes of riding.

But yes, given everything looks fine, I suspect the fibers are glazed or something. Some beefy springs would solve that.
 

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I removed my clutch cable return spring and was surprised how much of a floppy wet noodle the clutch lever was with just the Barnett springs providing resistance. Out of curiosity I swapped the factory springs back (only had 1000km of use) in and could have sworn the lever was stiffer at full pull.

To test out spring compression between Barnett vs stock, I rigged up a bunch of weights on a big car battery, the battery supported at one end by the spring, and measured the compression. I couldn't measure any difference. I think the Barnett springs are said to be 10-15% tougher than stock.
Funny that you brought up the Barnett spring compression rate. When I put mine in I looked very closely and could see no physical difference. I went as far as compressing the OEM and the Barnett springs alternately with a pair of slip joint pliers. Could not really tell a difference. I figured it was just me. Shrugged my shoulders and put them in.
I got my Barnett springs from Norton. The springs were noticeably stiffer than the OEM ones (just from feeling them by hand), and the clutch lever also became quite a bit stiffer after installing them. I don't use a clutch cable return spring since afaik it has no effect on the mechanics of a properly functioning clutch, it just makes the lever stiffer and does nothing else.
sbk1198 mentioned the different flavors of springs that Barnett makes for the 400; perhaps Norton accidentally sent you the OEM-replacement type (or springs from a poorly manufactured batch)?

My OEM clutch plates were definitely not dry when I replaced them with the Barnett ones. From what I remember (this was a while ago), the pull rod fitment was pretty snug.
 

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The Barnett springs were bought from Norton. It was the only Barnett springs they offered, so should be the tough ones.

The clutch fibres and steels currently installed have only done about 5000km. Both replaced when my original clutch started slipping. Incidentally the original clutch was also within thickness spec.
Ah ok, I assumed that was still all original plates. Never mind then...although people have burned clutches much faster than 5000km...although in racing applications. Is yours a street bike?

One thing I've noticed is that whenever I've looked at the clutch it has been really dry. I found it interesting in the Sportbike Trackgear Yoyodyne vid that Brian mentioned the pull rod should have a bit of slop in its hole because this is the primary oiling source of the clutch. Oil is pushed out around the outside of the pull rode and spun out through the inside of the clutch. He mentioned that if the tolerance is too snug, the clutch wouldn't get much oil and tend to overheat. A fix is dremelling a flat along the pull rod. I'm assuming the Yoyodyne people had told him this.
My pull rod seems rather snug, but I'm a bit loath to grind it.

Makes me wonder though, because my clutch is totally fine in the first 30 minutes of riding.

But yes, given everything looks fine, I suspect the fibers are glazed or something. Some beefy springs would solve that.
That's interesting that it doesn't slip in the first 30 minutes of riding. Also odd that you say it slips between 8000 and 10,000 rpm. Is it fine above 10k?? The main symptoms of a slipping clutch is it slips at high rpm in the higher gears. Usually 4th, 5th, and 6th gear once you get to about 2-3k rpm before the rev limiter (that can vary based on bike though and how badly the clutch is worn out or mis-adjusted).

My clutch never looked dry whenever I've opened it up. Everything inside is always coated with oil, including all the plates. If your plates overheated due to lack of oil, I would expect the steel plates at least to have a different color. Does it look like anything overheated in there?
 

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Discussion Starter · #7 ·
Ah ok, I assumed that was still all original plates. Never mind then...although people have burned clutches much faster than 5000km...although in racing applications. Is yours a street bike?



That's interesting that it doesn't slip in the first 30 minutes of riding. Also odd that you say it slips between 8000 and 10,000 rpm. Is it fine above 10k?? The main symptoms of a slipping clutch is it slips at high rpm in the higher gears. Usually 4th, 5th, and 6th gear once you get to about 2-3k rpm before the rev limiter (that can vary based on bike though and how badly the clutch is worn out or mis-adjusted).

My clutch never looked dry whenever I've opened it up. Everything inside is always coated with oil, including all the plates. If your plates overheated due to lack of oil, I would expect the steel plates at least to have a different color. Does it look like anything overheated in there?
The replacement steels look fine, normal silver. One of the new friction plates was a little darker than the rest, but still looked fine.
The original steels were darkened/blued, and the first set of friction plates were also darker compared with the new ones.

Yes, this is just street use, but fairly hard riding, gunning it off stop lights and the odd wheelie. Definitely not circuit racing levels of punishment though. With the slipper clutch activating constantly on track it would really get smoking hot.

I didn't really test 5th and 6th, primarily because it was so obvious and repeatable in 4th without going needing to go too quick. It's only really just started to be a problem.
The clutch would slip from 8000 and jump to 10,000 and slowly grab, dropping to 9700ish when it re-locked and continuing normally to redline. Seems like the slipping generates a bunch of heat and friction helping it regrip. The stock tune EU bike does lose puff in that last couple of 1000rpm.
Uphill it was particularly clear. On the flat it is hardly noticeable, and you have to be actively looking to pick it up.

It's possible oiling may actually be a problem here. I've been into my clutch a bunch and always struck by how dry everything is.
 

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Discussion Starter · #8 ·
I got my Barnett springs from Norton. The springs were noticeably stiffer than the OEM ones (just from feeling them by hand), and the clutch lever also became quite a bit stiffer after installing them. I don't use a clutch cable return spring since afaik it has no effect on the mechanics of a properly functioning clutch, it just makes the lever stiffer and does nothing else.
sbk1198 mentioned the different flavors of springs that Barnett makes for the 400; perhaps Norton accidentally sent you the OEM-replacement type (or springs from a poorly manufactured batch)?

My OEM clutch plates were definitely not dry when I replaced them with the Barnett ones. From what I remember (this was a while ago), the pull rod fitment was pretty snug.
I'm sure I felt the same way when I first installed my Barnett springs.

Interestingly they have less coils than stock, and the wire guage is smaller. Visual comparison you would say the stock spring looks more built to last of the two.

The return spring is merely a preference for clutch feel.
 

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I didn't really test 5th and 6th, primarily because it was so obvious and repeatable in 4th without going needing to go too quick. It's only really just started to be a problem.
The clutch would slip from 8000 and jump to 10,000 and slowly grab, dropping to 9700ish when it re-locked and continuing normally to redline. Seems like the slipping generates a bunch of heat and friction helping it regrip. The stock tune EU bike does lose puff in that last couple of 1000rpm.
This is quite odd. I haven't seen this behavior before out of a clutch.
 

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blued usually means they got hot and warped, the steel plates that is. mine were perfect silver, no darkness and no blueing at all.
I have seen some pretty bad ones over the years on other bikes...some being mine, lol.
I distinctly remember some that looked like the blued titanium exhaust pipes that were easily visibly warped
 

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Discussion Starter · #12 ·
blued usually means they got hot and warped, the steel plates that is. mine were perfect silver, no darkness and no blueing at all.
I have seen some pretty bad ones over the years on other bikes...some being mine, lol.
I distinctly remember some that looked like the blued titanium exhaust pipes that were easily visibly warped
Some of my first set of steels were blued but still flat - tested against window glass, and stacking them on top of each other.

My second set of steels still looks the standard silver colour, but have ended up slipping for whatever reason.
 

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Some of my first set of steels were blued but still flat - tested against window glass, and stacking them on top of each other.

My second set of steels still looks the standard silver colour, but have ended up slipping for whatever reason.
It's more likely the fiber plates that are slipping. I've never had to replace steel plates on any bike I've owned. They last a very long time, unless something odd happens. The fiber plates though, I've replaced plenty of times of all the bikes I've had for at least a couple of years.
 

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Discussion Starter · #14 ·
It's more likely the fiber plates that are slipping. I've never had to replace steel plates on any bike I've owned. They last a very long time, unless something odd happens. The fiber plates though, I've replaced plenty of times of all the bikes I've had for at least a couple of years.
Interestingly I left the original blued steels in when I first replaced the friction plates. The clutch had zero improvement. It was incredibly annoying.
So I forked out for new steels and instantly the clutch was tight again. Bizarre.
 

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Discussion Starter · #15 · (Edited)
Ok, so the CBR600RR EBC CSK101 springs arrived and I've installed them. They are 47mm long and fractionally smaller diameter, around 19.7mm vs 20mm on the stock ninja springs. Easy to install and fit fine. During install you need to lean on the spring bolts a little, to compress the spring slightly, to get each bolt started.

Testing their strength with my fingers, I think I can compress them a similar percentage of their length as the stock and Barnett springs. So could be a similar spring rate.

The clutch lever feels good and seems about twice as heavy as the Barnett springs. Still a light clutch. My cbr250rr clutch is probably 30-40% heavier again, and that's not a heavy clutch.

I've just been for a ride. Things are feeling good. No clutch slip. Time will tell.
I am using the Norton modded clutch pull rod with the shoulder machined down, thus weaker. That'd probably be my only real concern with this setup.

When I started this thread I figured this might be a known mod by racers, given Sportbike Trackgear's Brian had done it for his son's 400 race bike. Therefore I put in race section. I'd say it definitely would be a good mod if you're having slipping issues, but you're probably not going to get much slipper clutch action. Brian mentioned this was a reason they were going Yoyodyne route for the race bike.
I haven't tested the slipper effect with these. I gave them a decent test, but didn't thrash on them.

From left - EBC spring, Kawasaki spring, Barnett spring.
Plant Gas Font Metal Coil spring


Plant Gas Font Metal Coil spring
 

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Discussion Starter · #16 · (Edited)
Well about 200km later my clutch is slipping again. Farout. Doing the same thing of slipping in 4th when the power comes in. No slip in 5th. I'm guessing this is because 4th is the closest to a 1:1 ratio or something? slipping in 4th, but not 5th.

Anyway I pulled the clutch apart yet again and it's very dry. I only found 1 drop of oil in the whole pack, on the back of the 2nd friction plate on one of the tabs.
All the friction pads are completely dry. I can rub between the pads and get no oil film on my finger. The steels are also dry. You can wipe your finger around the whole steel and not have noticeable film on your finger. Like nothing that would be visible on a paper towel even. I've actually added oil to the steels to stop my fingerprints rusting them while they are out of the bike. I noticed it happened a little last time I had them out.

The bike was still mildly warm after a ride today, plus I idled the bike for 30 seconds before pulling off the clutch cover.

I've never opened a wet clutch before owning this bike, so am no expert on how oily it should be. But seems crazy dry for something called a "wet" clutch.

I did notice three holes in the clutch hub to allow oil to spin out to back middle and front plates. Nothing blocked anywhere.
Both the Norton machined pull rod and my stock pull rod seem to have similar wiggle room (next to none), so both should allow similar oil access.

I'm tempted to start the bike with the clutch cover off to see if oil even comes through the shaft, but I'm guessing it would spray all over the place.

Thoughts?

(note I did put some oil on plates below, after the fact)
Brown Font Circle Wood Pattern


One of the clutch hub oiling holes. Looks fine.
Tire Wheel Automotive tire Light Motor vehicle


The clutch hub does have a little oil pooled in the bottom.
Tire Automotive tire Motor vehicle Wheel Alloy wheel
 

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Just thinking out loud here but your friction plates don’t look dry in the photo. When you pull them out they won’t be dripping wet.

With the pressure plate installed is the pull rod able to freely move?
 

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Discussion Starter · #19 ·
As I was pulling the stack out, I added oil to some of the steels which I then stacked on the removed frictions, transferring some oil.
But the whole lot is incredibly dry. It's like any vestige of residue left is from my original assembly a couple of days ago, and there's not enough of that to even get the light reflecting off my finger after rubbing multiple plates.

In this vid Brian actually has oil film on the plates during disassembly.

Meanwhile the vestiges of oil I have are like what's left over after you spill a few drops of oil on the concrete, wipe it off, then one more wipe with a paper towel. But if you get the light just right you can still see where you spilt oil. That's how little of it I have on every single plate.
 
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