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1982 kz440a
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Discussion Starter · #1 ·
I searched, and I'm shocked this hasn't been asked before, I'm having trouble sourcing oem clutch discs for a kz440. I used oem plates and discs with aftermarket (stiffer) springs on all my bikes in the past. Can someone reccomend a good aftermarket set? I don't want smooth, I want something that fucking grabs hard. The barnett discs cost twice as much as ebc. Are they worth it?
 

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I searched, and I'm shocked this hasn't been asked before, I'm having trouble sourcing oem clutch discs for a kz440. I used oem plates and discs with aftermarket (stiffer) springs on all my bikes in the past. Can someone reccomend a good aftermarket set? I don't want smooth, I want something that fucking grabs hard. The barnett discs cost twice as much as ebc. Are they worth it?
Hipster,
Have you tried Barnett Clutches ? I've sourced clutch bits for everything from a Suzuki X 6 Hustler to out YSR 600 racer and they've always come through.
Cheers
 

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I've never noticed a significant clutch performance difference with a change of manufacturer, only a difference in what oil works best with a wet clutch. Lots of modern enduro bikes are now using carbon fibre plates in their clutch instead of cork fibre, the difference being carbon fibre plates are extremely durable, expensive and thin enough such that a greater number of plates can be fitted into the same clutch pack area. Motivation for fitting a higher performing clutch is extreme horsepower and abuse in racing conditions, but for street use on a non-modified engine I suspect you are wasting money to upgrade clutch parts since a KZ440 isn't going to produce sufficient torque to overcome the clutch originally designed for the bike. Stronger pressure springs are going to increase the pull effort at the lever and kill your clutch cable and mechanical clutch actuator parts that much faster. If the original plates are still in spec for thickness I'd be putting them back in and run it stock.
 

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I put a heavy duty Barnett clutch in my Ford van once, it promptly busted the stock clutch fork because that part couldn't handle the heavier springs. I suspect that is what might happen to your clutch cable as your clutch is not hydraulic operated.
 

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Not an upgrade, a necessary replacement. It's slipping. I though the stiffer springs put more pressure on the whole assembly. Am I that retarded?
If the clutch is slipping because of plate wear then the plates should show damage or a glazed surface or the pad material should measure as being too thin by the service manual spec.

If a manufacturer wants to make a wet clutch carry more power they increase the number of friction plates or the diameter of the entire clutch, or they move the clutch up to the crankshaft and run it as a primary clutch where the forces on that part are greatly reduced.
 

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I put a Barnett kit in my bike & it has been good. They are a popular drag bike mod because they typically have very heavy springs and it pretty much locks the clutch solid when you dump it. Grab is what they are best at. As expected the springs were much heavier and the clutch pull was harder than I wanted on the street. I have 2 stacked cup style springs and ended up running one Barnett stacked with one OEM & it eased the pull a bit.
 

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Not an upgrade, a necessary replacement. It's slipping. I though the stiffer springs put more pressure on the whole assembly. Am I that retarded?
Yes, stiffer springs put more pressure on the plates, but that Also means it puts more tension on the cable to pull the clutch, which can mean higher risk of snapping a cable. It also means Popeye forearms when riding in stop and go traffic. Just trade offs to consider.
 

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Barnett plates can be a little grabby when cold but offer great friction. Lots of bikes use the same size plates and it's most ;likely that they can supply a suitable set.
 

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Discussion Starter · #10 ·
Yes, stiffer springs put more pressure on the plates, but that Also means it puts more tension on the cable to pull the clutch, which can mean higher risk of snapping a cable. It also means Popeye forearms when riding in stop and go traffic. Just trade offs to consider.
I'm gonna change the cable, gasket, springs, friction plates all in one shot. I just did an oil change (Castrol gtx) 34miles ago so I'm gonna lay the bike on its side. I'm hoping the discs aren't warped because I can't find them. I pulled the trigger on ebc corks and ebc springs (rated 10% stiffer than stock)
 

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Might wanna drain the oil first anyway into a clean pan and put it back in after you're done servicing your clutch. Don't wanna risk oil seeping through the piston rings and into the cylinders when you lay it on its side. Plus chances are you'll have to presoak the disks anyway so you can just throw them in the same pan for a couple of hours
 

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Discussion Starter · #12 ·
Might wanna drain the oil first anyway into a clean pan and put it back in after you're done servicing your clutch. Don't wanna risk oil seeping through the piston rings and into the cylinders when you lay it on its side. Plus chances are you'll have to presoak the disks anyway so you can just throw them in the same pan for a couple of hours
[/QUOT
Does anyone else think this is a legitimate concern?
 

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Discussion Starter · #14 · (Edited)
Yup. The part about soaking the disks is also important.
ok, well if I'm draining it, I'm putting fresh in regardless of mileage. The bike sat for years before the last 34 miles so we'll call it an "oil flush" What's your favorite oil for a wet clutch?

actually, maybe I'll throw the 34mile oil back in and break in the new clutch then change it, does anyone have an opinion about particle contamination from a fresh clutch?
 

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Pretty sure most VJMs use 10w40. Most guys here are sticklers for actual motorcycle oil because of it's wet clutch formula but I've always just used regular conventional and added motorcycle oil stabilizer for the same results. Dont ever use full synthetic. As far as particle contamination, just service your oil filter when you change your oil
 

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Discussion Starter · #16 ·
Pretty sure most VJMs use 10w40. Most guys here are sticklers for actual motorcycle oil because of it's wet clutch formula but I've always just used regular conventional and added motorcycle oil stabilizer for the same results. Dont ever use full synthetic. As far as particle contamination, just service your oil filter when you change your oil
I don't think this is correct because all the "motorcycle specific" oils are synthetic. The difference is they dont contain "friction modifiers" that a typical (car) synthetic would
 

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Pretty sure most VJMs use 10w40. Most guys here are sticklers for actual motorcycle oil because of it's wet clutch formula but I've always just used regular conventional and added motorcycle oil stabilizer for the same results. Dont ever use full synthetic. As far as particle contamination, just service your oil filter when you change your oil
Hipster,
I had not even considered changing clutch springs with anything other than new OEM. Springs are made of steel and even with them being made of spring steel they still tend to loose some tension over the years. The folks who made that motorbike in the first place considered how it was to be used and the clutch parts were installed to work with that consideration (horsepower) unless you are building more horses then OEM (Barnett offers more than one spring tension most times) springs should be fine. On our race bikes we often will alternate one stock tension with one heavy duty spring if we find we are having slippage while exiting a corner. Do remember that on non-drag bikes you do not want a huge drive line shock on down shift not a big problem but we don't try for instant lock up.
As to oil: It is the life's blood of your engine. I will admit that we don't pay for our engine oil; this said I have never scrimped on oil quality. Most engines don't take even quantities of oil so theres always some left over to soak clutch discs in. Saving drain oil from a clutch change in my humble opinion is "NUTS" you have a huge open container that crap can get into. The engine has (as you said) been sitting and fuel can seep past the rings and into the sump; bits of crud that would stay hidden in little spots within the engine have now found their way into that same sump. WTF put in new motorcycle oil. You don't need top of the heap racing stuff but a good name brand oil is good insurance.
LOL Now the Surgeons most likely wring out the sponges after surgery and re-infuse you with that but blood is costly and it's a long walk down to the blood bank. For heaven's sake one little piece of glop can destroy your engine when you have it apart replace the oil and filter.

Cheers
 

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Discussion Starter · #18 ·
Hipster,
I had not even considered changing clutch springs with anything other than new OEM. Springs are made of steel and even with them being made of spring steel they still tend to loose some tension over the years. The folks who made that motorbike in the first place considered how it was to be used and the clutch parts were installed to work with that consideration (horsepower) unless you are building more horses then OEM (Barnett offers more than one spring tension most times) springs should be fine. On our race bikes we often will alternate one stock tension with one heavy duty spring if we find we are having slippage while exiting a corner. Do remember that on non-drag bikes you do not want a huge drive line shock on down shift not a big problem but we don't try for instant lock up.
As to oil: It is the life's blood of your engine. I will admit that we don't pay for our engine oil; this said I have never scrimped on oil quality. Most engines don't take even quantities of oil so theres always some left over to soak clutch discs in. Saving drain oil from a clutch change in my humble opinion is "NUTS" you have a huge open container that crap can get into. The engine has (as you said) been sitting and fuel can seep past the rings and into the sump; bits of crud that would stay hidden in little spots within the engine have now found their way into that same sump. WTF put in new motorcycle oil. You don't need top of the heap racing stuff but a good name brand oil is good insurance.
LOL Now the Surgeons most likely wring out the sponges after surgery and re-infuse you with that but blood is costly and it's a long walk down to the blood bank. For heaven's sake one little piece of glop can destroy your engine when you have it apart replace the oil and filter.

Cheers
good point!
 

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Hipster,
I had not even considered changing clutch springs with anything other than new OEM. Springs are made of steel and even with them being made of spring steel they still tend to loose some tension over the years. The folks who made that motorbike in the first place considered how it was to be used and the clutch parts were installed to work with that consideration (horsepower) unless you are building more horses then OEM (Barnett offers more than one spring tension most times) springs should be fine. On our race bikes we often will alternate one stock tension with one heavy duty spring if we find we are having slippage while exiting a corner. Do remember that on non-drag bikes you do not want a huge drive line shock on down shift not a big problem but we don't try for instant lock up.
As to oil: It is the life's blood of your engine. I will admit that we don't pay for our engine oil; this said I have never scrimped on oil quality. Most engines don't take even quantities of oil so theres always some left over to soak clutch discs in. Saving drain oil from a clutch change in my humble opinion is "NUTS" you have a huge open container that crap can get into. The engine has (as you said) been sitting and fuel can seep past the rings and into the sump; bits of crud that would stay hidden in little spots within the engine have now found their way into that same sump. WTF put in new motorcycle oil. You don't need top of the heap racing stuff but a good name brand oil is good insurance.
LOL Now the Surgeons most likely wring out the sponges after surgery and re-infuse you with that but blood is costly and it's a long walk down to the blood bank. For heaven's sake one little piece of glop can destroy your engine when you have it apart replace the oil and filter.

Cheers
What this guy says is full of sense concerning the oil, You were right in saying you were planning on discarding that oil with 34 miles on it the first time. However if you soak your new disks in new oil in a clean container and simply cover it I see no reason why that oil can't be used in the engine. I stand by what I said about not using full synthetic oil though, If you are using OEM style cork disks then they will slip.
 

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Discussion Starter · #20 ·
What this guy says is full of sense concerning the oil, You were right in saying you were planning on discarding that oil with 34 miles on it the first time. However if you soak your new disks in new oil in a clean container and simply cover it I see no reason why that oil can't be used in the engine. I stand by what I said about not using full synthetic oil though, If you are using OEM style cork disks then they will slip.
yeah but just read the marketing rhetoric they use on "motorcycle" oil:


  • Mobil 1 Racing 4T 10W-40 is an advanced full synthetic motorcycle oil recommended by ExxonMobil for four-stroke motorcycle engines in high performance motorcycles
  • Delivers excellent 3-way protection for your engine, transmission and wet clutch
  • Reduces frictional losses and provides optimized balance of engine performance
It has to be true!

so fucking confusing dude.... It has no friction modifiers and simultaneously reduces friction losses WTF?
 
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