TOPIC:

Are there any practical advantages to using heavy duty clutch springs/friction plates in a non-racing application? Obviously the parts are built for abuse, but are they really needed for normal to occasionaly aggressive riding? Is hand fatigue an issue with heavy duty springs?,or not. It looks like time for a clutch rebuild because it is starting to slip when I twist it hard and fast, in the mid to upper rpm zone. I've already got NOS steel plates off ebay last year because I saw this coming.

For a stock 900/1000 I would recommend staying with the stock style clutch plates and springs. The stock clutch is very good IF the plates are in decent condition.

Once you start to increase the HP, it's worth looking at the heavy-duty clutch pack.

I run a heavy-duty pack in my turbo bike and you can notice the heavy action on the lever. Additionally, the extra-disk clutch disks tend to be a little grabbier than stock - not real bad, but noticeably more aggressive.

I have recently put the heavy duty clutch kit in one of my bikes and absolutely love it. Very smooth shifting.Gets my vote.

Sorry, aparently I wasn't logged in when I posted the above so you couldn't see my bike. I was just wondering if a heavy duty kit was worth puting in a stock 650? I looked through my repair manual and it appears to be a simple job, as long as no major components are damaged or seriously worn. What exactly is it that lets a clutch slip?, worn friction plates, steel plates, springs, a combo of the above to a greater or lesser extent?

The fingers on the basket could be grooved causing the dics or metal late "tangs" to hang-up on them. When you remove the cover you'll know. The fiber-discs can also wear thin enough from years of slipping the cultch, or just normal wear. I know this isn't going to go toward a "what oil to use" thread, but that's why I use Motorcycle Specific Engine Oil, as it's for wet clutches. Just my preference. It's not a hard job to do, just getting that nut off needs an impact.

Really the same answer for the small 4's - the stock clutch can take a serious amount of abuse before it starts slipping. The key is the state of the plates.

When I pull a clutch apart, I inspect all the plates - often you will find cracked or broken plates. I recently removed a clutch pack in a Z1 where three of the fiber plates were badly broken and one of the steel plates was broken (the first I've seen) - yet the clutch still worked.

The oil pan had a number of chunks of the fiber plates - so if you do find broken plates, make sure you can account for all the pieces...

When reusing the metal plates, I usually scuff them with a Scotchbrite pad to remove the glaze on them.

The clutch will slip if the friction plates are too thin. These can be measured with a micrometer or caliper to determine if they are within spec. The other thing that will allow slipping is very weak clutch springs. The springs tension the friction plates and steel plates when the clutch is engaged.

I suggest you use the stock springs if at all possible as heavy duty replacements make clutch pull much harder.

What about the on/off of a performance clutch? Do they take the abuse that a street rider gives them, or are OK to slip but might not last as long? Good points here guys.

Oh by the way I'm wearing my Z1 Industries Shirt right now.

I am going to install the APE clutch over the winter. How will this affect the streetability of the bike?

This thread is good info for me as I recently won an auction for a Barnett "extra plate" heavy duty clutch kit with springs. I corresponded with the factory rep to get some additional info about this kit. He told me it would be fine in a GPz with mild performance mods and I'm looking forward to installing it this winter as my clutch is a little worn and slips some. He also instructed me to install the extra friction and steel plates as the clutch pack is guaged to a specific total thickness. Apparently this kit is no longer made, but the "destructions" list it as specifically for an 81 GPz550, so I'm good to go. I also have read on this forum (I think) that these h.d. Barnett kits will last a good long time......I'm hopeful.

The barnett (and others) extra-disk clutch packs are good and robust. They do wear out, but it takes a lot. The usual issue is you will see wear on the outside tangs of the friction plates and wear on the innder aluminum hub. I ran one of these clutch packs in the late 1970's, put 30,000+ miles on it, ran 200+ 1/4 mile drag passes and hammered it everyday on the street... I replaced the center hub once and a couple of the plates.

letthegoodtimesroll wrote:

I am going to install the APE clutch over the winter. How will this affect the streetability of the bike?

Dang Neil, you were the guy that out-bid me? That's why I have my ebay name in my signature. I didn't need it after all.