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When I originally built my Fury R1 back in 2007, I upgraded clutch spring plate for a 20% stiffer Yamaha engineering Corporation (YEC) race version. Back then, the part cost me £61.95 inc. VAT from Orwell Motorcycles 
[part number 4XV-16334-70].
In June 2013, the clutch was replaced by AB Performance and a Barnett clutch conversion fitted at 9530 miles. I got all the spare parts handed back to me. I also got a spare set of Barnett springs as the kit comes with two sets; one for motorbikes and a stiffer set for bike-engined cars.
The steel plates and friction plates are the same but, in a BEC installation there is no anti-judder plate, so an extra friction plate is installed (8 in total). This extra plate is physically smaller than the others.
In November 2019 I occasionally felt that the clutch was starting to slip in the higher gears. Over winter I had the engine out to replace the alternator but didn't do the clutch. Now in May 2020 at 14,350 miles the slipping is becoming more noticeable.
The Barnett website, shows that I need the 302-90-10055 kit , which consists of 301-90-10005 × 7 and 301-90-10831 × 1.
There are 8 kevlar friction plates and one is slightly smaller than the other 7.
It makes sense to replace the steel plates at the same time and this requires 7 × 401-90-078020 .
The friction plates and steel plates came to £131.22 delivered from PDQ Motorcycle Developments .
The steel plates currently in place may be OK but, I ordered some new ones just in case.
The Barnett clutch springs can also wear over time and lose some of their spring force. I also want to replace the clutch springs but right now I don't know what the part number is for the correct springs. I'm waiting on Barnett to respond to my query with the right part number.
From what I've ben told so far, I think the part I require is 501-56-06015HD.
Before replacing the clutch components, it is worth talking about the oil. Some people say the clutch will slip with fully synthetic oil and others say it won't. Interestingly, the oils I've had provided by AB Performance have all been fully synthetic and the only time I've experience clutch slip is when the friction plates have been worn.
As I understand it (having done a lot of reading on this subject now!), sythentic oil is fine as long as it is not SJ (energy conserving) rated. There is a small circular label on the back of the bottle that says so, if it does, stay away.
There is no problem running synthetic oils in a wet clutch system, as long as they do not contain molybdenum disulfide which is where that energy rating comes from. This is like a graphite dry lubricant suspended in a liquid carrier that plates out on metal surfaces. Avoid the energy conserving oils (automotive SJ and above). This will coat things, causing the slip.
The Barnett installation notes also say do NOT use an oil with 'friction modifiers', quoting the JASO-MA, JASO-MA1 and JASO-MA2 specifications.
The JASO standards are explained here and here . Put simply, JASO T 903 establishes two performance categories: MA for motorcycles fitted with a wet clutch and MB for motorcycles fitted with Automatic transmission (Scooters).
These are the oils I have used since 2007, latest first:
This is the recommended oil for the R1 engine and meets the 'JASO T 903 : 2011' MA specification. It is a fully synthetic oil. It can be bought from many places and I got my last lot from Amazon.
The specification is clearly shown on the back.
This oil was from AB Performance . It is a fully synthetic oil.
The specification is clearly shown on the back.
Because of the orientation of the engine in the Fury, it is fairly easy to work on the clutch with the engine in place.
The first task is to soak the new friction plates (I did the steel plates as well) in oil over night.
Next, I removed the clutch cable. This is easy on my car as the cable end has a clamp that bolts to the clutch arm.
The next step is to remove the bolts holding the clutch cover in place. It's a good idea to stick these in cardboard, to capture where each one goes. They all look the same to me but one of them has a cable guide on it.
You can remove the clutch cover with all the oil in place as it doesn't come up this high in the engine. This then reveals the Barnett clutch mechanism.
AB Performance installed these gold springs (which I'm pretty sure are not the heavy duty ones) and I also got the other set supplied with the kit as spares. These are longer and look thicker though.
The last steel plate and (small) friction plate are held in place by a retaining ring or 'piano wire', which runs around the boss and is held in place by the ends passing through a hole. The ends are bent to form a spring clip.
Undoing the piano wire basically involved using a pair of pliers to squeeze the spring clip and push it back through the hole.
With the 'piano wire' removed, the last steel plate and smaller friction plate can be removed.
Last to come out are the two inner metal plates. The very inside one is flat but the other one leans in from its outer edge to inner edge. It has to be installed the right way and has 'OUT SIDE' written on it. These both needed a good clean.
Looking at my clutch basket, there is some wear and notching were the friction plates and steel plates meet it. It's not too bad and there isn't much I can do about it either. If the notching is too bad, this can prevent the plates from moving freely.
Putting it back together is basically the reverse of the dismantling process but, I've not put the 'piano wire' back in. Many people say it can break and cause real problems in the engine.
The Barnett pressure plate is fitted and the spring bolts torqued up to 6 ft-lbs (about 8Nm).
The service manual says do the clutch cover bolts up to 12Nm but this is too tight in my view and some owners have snapped bolts using this torque setting. I went with 8Nm.
