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Discussion Starter · #42 ·
You need to remember that when the clutch is assembled the pull rod isn’t shoved all the way in.

How wet do these look?
Yeah, the pull rod is about 2mm out from the shaft, unless the clutch is worn out, in which case it'll be bottoming out on the shaft. I tried I range of when I started the bike, all the way in to about a third of the way out.

Hard to say from a distance, but top one looks dry if I had to guess.
 

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something like this?

Can you remember how much of a slot you put into it?
IIRC, .062 ball, .031 deep. It was 20 years ago FFS…

Some people also drilled more holes in the inner hub. It was common to try to get more oil on the clutch pack.

Some riders also heavily leaned bikes to right while engaging/disengaging clutch (in neutral) after burnout to try to submerge the plates

I did it on my manual mill, not on a CNC.
 

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I never even noticed those holes in the hub before lol Yeah what you said makes sense now about the oiling. I don't know, this is an odd issue, I'm of no help on this. I have heard good things about the Yoyodyne clutch though, so if all else fails and you don't mind spending the money, might be worth just upgrading to one.
 

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I got nothing more here also. Honestly never had any reason to suspect not enough oil. I doubt oil through the shaft around the pull rod is the problem. I think the oil mist that’s kicked up from the spinning clutch is the major source of oiling. When the side cover is on and the bike level look at the site glass to estimate where the oil level is. Even though not submerged in it I’ll bet the spinning clutch and cam chain kicks up a pretty good fog. I have looks at a wet clutch Ducati with a plexiglass side cover when running and it’s interesting. There’s not as much oil flying around as you might think. It’s like looking at the side window of your car when driving in the rain. Just mist and droplets swirling around on the clear cover.
 

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Couple points here, again from a drag background...

A quickshifter will help your clutch life if you don't already have one. On each shift, especially at full throttle the clutch is slipping and trying to hold onto the engine, same with a downshift, but the match speed comes much easier. If it is never disengaged it doesn't have to fight that unless you have the HP to overcome it.

if you are reusing your steel plates you need to check them for flat/coning. If they are not flat, don't reuse. I use a surface plate, I have used thick glass in the past. Its all about maximizing contact area, something these bikes seem to be struggling with You should also deglaze steel plates. I've done it different ways, bead blasting, hand sandpaper, D/A sand, spin in a lathe sand paper...

Stack height of the clutch is the critical number, I don't know what that number is for these bikes, but it basically is the height that makes it so that the pressure springs are putting the correct clamp on the pack. If the pack is short then the clamp load is low. In my experience you can juggle plate thicknesses and new/old to get this number.
 

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Discussion Starter · #47 · (Edited)
Well I got a reply back from Yoyodyne, but no specifics on mods to get oil.

"Grant

Everyone has issue with those clutches

Oil will give it better slip characteristics when moving off from a start
In rare circumstances, synthetic oils will make the clutch slip.

When it does slip, the answer is more spring pressure.
You may have to shim the springs you have to get it to stop slipping.
(I am assuming the motor is mostly stock)

or

we have this clutch for stock motors.

https://www.yoyodyneti.com/product-p/t23503c.htm


Fred"

Hi Fred, thanks for the reply.

Given my current clutch is bone dry, the Yoyodyne would require some modification to get some oiling?

Thanks,
Grant


"Given it is bone dry, that would be a good idea for any clutch."


So yeah, I'm going to grind my clutch pull rod when I get a moment.
At times like these I wish I had any sort of vice or clamps, but whatevs. Still got me hands for that.
 

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Discussion Starter · #48 ·
Well peeps, I sent it and ground my pull rod a bit.
The clutch definitely seems to be getting some oil now. I haven't had time to ride it. Hopefully sometime in the next few days.
My current friction plates have probably been pretty toasty and slipped a good bit. I don't know how redeemable they are.


My high end wheelie bin clamp worked very well.

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Discussion Starter · #49 ·
My clutch is still slipping. I'm really fed up. I've had the clutch cover off at least 10 times in the last three weeks.
Same story where the clutch is good for the first 30-40 minutes, then starts slipping in 4th from 8000rpm when everything is heat soaked.

The good news is I am now getting at least some oil to the front and back of the clutch pack. The two large friction plates in the middle are dry, but I doubt much can be done about that.
Thankfully my original clutch cover gasket is still good after all this. I always put an oil film around it before installation and it has paid off.

So after my oil mod, when it still slipped, I tried wet sanding all my original steels with 400 grit. A fairly common recommendation online. It brought the steels back to silver colour nicely. I was feeling hopeful.
I went for a ride and it all seemed good at first, as it always does, then started to slip when everything got hot. Aargh!

So I'm now starting to order my third set of friction plates.

I want the Barnett kevlar friction plates, but they aren't in NZ anywhere. The OEM friction plates are available locally, but they want to charge $175 NZD for them. (my last OEM set was $140 NZD) So I've been trying to find what other aftermarket options exist.
Some might find this info handy in future.

Referring to Barnett's catalogue and EBC's website. A ton of bikes share the same clutch friction disks.
EBC Brakes Motorcycle Clutches

But only the 2016+ KTM 390 range and 2013+ Triumph Daytona 675 have the right number of 3x smaller friction plates with enough larger plates.

2013+ Triumph Daytona 675/675r = 3x of the small plates and 6x of the large plates. EBC CK5664 (not stocked in NZ, great...)
2016+ KTM Duke 390/RC390 = 3x of the small plates and 4x of the large plates. EBC CK5666 (again, not stocked in NZ, great...)




front of clutch pack now actually has some oil clinging to it. Similar amount at the back of the pack.
Automotive tire Automotive design Rim Watch Automotive wheel system


The 2 large friction plates are basically dry.
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My first set of steels wet sanded radially with 400 grit. Looked good again.
Sports equipment Sports gear Ball Font Football
 

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That's such a weird issue. This is starting to drive me nuts too, just because it makes no sense, even thought it's not even my bike! LOL Plates look fine, stack height is within spec you said, works fine for the first half hour, then slips in 4th gear but only around 8000-10,000 rpm. Does it do that in 5th and 6th gear too? Or does it do it at different RPM ranges in those gears?
 

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Discussion Starter · #52 ·
It's doing my head in. I'm very frustrated. I'd switch to Yoyodyne but really don't want to pay that much.

I'm pretty sure there is no chain jumping or I'd feel and hear it. Sprockets are still stock and look fine. The front sprocket has the bent washer and factory marking.

I figure the reason it happens in 4th gear but not 5th and 6th is because 4th is closest to 1:1 drive with 8000RPM being the point it really starts to make power.

I wondered if it is was something to do with the oil, but the clutch had been fine for a few 1000k's on the same oil before it started slipping. Regardless I changed the oil + filter and switched to mineral and still had the same problem. Although if there were contaminants I don't know if a single oil change would resolve it.

I'm wondering if it's something to do with the friction material basically going off and never being recoverable from that point?
But then there was also the weird thing where I originally just replaced the clutch fibers, keeping the original steels, and the clutch slipped as before. The original steels were a little discoloured but still flat.
With new steels the clutch immediately returned to 100% for the next 5000ish kms.
Nothing makes sense.

Video of it happening
 

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It's doing my head in. I'm very frustrated. I'd switch to Yoyodyne but really don't want to pay that much.

I'm pretty sure there is no chain jumping or I'd feel and hear it. Sprockets are still stock and look fine. The front sprocket has the bent washer and factory marking.

I figure the reason it happens in 4th gear but not 5th and 6th is because 4th is closest to 1:1 drive with 8000RPM being the point it really starts to make power.

I wondered if it is was something to do with the oil, but the clutch had been fine for a few 1000k's on the same oil before it started slipping. Regardless I changed the oil + filter and switched to mineral and still had the same problem. Although if there were contaminants I don't know if a single oil change would resolve it.

I'm wondering if it's something to do with the friction material basically going off and never being recoverable from that point?
But then there was also the weird thing where I originally just replaced the clutch fibers, keeping the original steels, and the clutch slipped as before. The original steels were a little discoloured but still flat.
With new steels the clutch immediately returned to 100% for the next 5000ish kms.
Nothing makes sense.

Video of it happening
I missed it. When? Never mind. I saw it. Weird!!!
 

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I figure the reason it happens in 4th gear but not 5th and 6th is because 4th is closest to 1:1 drive with 8000RPM being the point it really starts to make power.
4th gear is not closest 1:1 ratio. In 6th gear it's always closes to 1. I think on these bikes it's like 1.03 or something like that, then 1.1-1.2 somewhere in that range for 5th gear, and 4th is like 1.3ish, all the way to like 2.9 for 1st gear. 6th gear is always the closest on any bike, that's why it's much easier to spin the rear wheel and turn the motor over on a stand when you put the bike in 6th gear. And that's why USUALLY when a clutch is really slipping it starts to go at high rpm in the higher gears, and it'll just slip all the way to the rev limiter, especially in 5th and 6th.

Nevertheless, yeah the video shows perfectly what's going on, but still baffled as to why.
 

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Like everyone has been trying to tell you it has nothing to do with the amount of oil. Just forget that. It’s not the steel plats if they are flat, blue or not. Forget that. If the friction plates measure good forget that. Whether or not you use the judder spring has nothing to do with it. Forget that.

There’s not much left. Like Norton told you check spring pressure. But I think you did that.

I hate to best a dead horse but are you absolutely sure you have plenty of slack in the cable? I know my son cane from riding two stroke motocross bikes and fried the clutch on his 400 like his second time on track.
 

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Discussion Starter · #58 ·
4th gear is not closest 1:1 ratio. In 6th gear it's always closes to 1. I think on these bikes it's like 1.03 or something like that, then 1.1-1.2 somewhere in that range for 5th gear, and 4th is like 1.3ish, all the way to like 2.9 for 1st gear. 6th gear is always the closest on any bike, that's why it's much easier to spin the rear wheel and turn the motor over on a stand when you put the bike in 6th gear. And that's why USUALLY when a clutch is really slipping it starts to go at high rpm in the higher gears, and it'll just slip all the way to the rev limiter, especially in 5th and 6th.

Nevertheless, yeah the video shows perfectly what's going on, but still baffled as to why.
Oh right, good to know. I never had a problem in 6th at low-mid RPM, but then I wasn't testing the upper rev range. Not so easy on public roads. It is possible there is some slippage there I haven't seen.
 

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Discussion Starter · #60 ·
Like everyone has been trying to tell you it has nothing to do with the amount of oil. Just forget that. It’s not the steel plats if they are flat, blue or not. Forget that. If the friction plates measure good forget that. Whether or not you use the judder spring has nothing to do with it. Forget that.

There’s not much left. Like Norton told you check spring pressure. But I think you did that.

I hate to best a dead horse but are you absolutely sure you have plenty of slack in the cable? I know my son cane from riding two stroke motocross bikes and fried the clutch on his 400 like his second time on track.
Definitely enough slack in the cable and clutch lever. Another way of checking is feeling how loose it is at the clutch cover lever. It's plenty loose.

During one of my many clutch tests earlier on, before posting here about 600RR springs, I tested the stock clutch springs and did get the clutch lever adjustment wrong. That clutch slip was significant. That moment was the only time I've adjusted the clutch wrong in the 25,500km I've put on this bike.

The increased oiling may not resolve the current issue if things are glazed, but hopefully it'll help going forward for the life of future clutches.
It was definitely dry beforehand, now it looks similar to the oil in the sportbiketrackgear vid. Can only be a good thing.
 
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