Is it the clutch slipping?

I want to run some of these symptoms by you guys. Keep in mind it's an '83 kz550 chain-driven and I'm about 50 lbs from the max load. :blush:

I bought a bike, downloaded a Clymer manual and adjusted my clutch cable because it felt weird, it took awhile until I realized the manual was backwards.

I had the rear tire changed and the tech said he adjusted the clutch cable. D'oh, I did it wrong.

I changed the clutch cable because it was previously pinched. It took me a while to get it right because of inexperience.

It was a bit slippy at high rpm. I changed the oil & filter, Pennzoil, and adjusted the cable again. I took it out for a short ride and it felt perfect.

The next long ride had the same slippiness under load uphill and high rpm. It felt better but not perfect after it warmed up a good 10 - 15 minutes or at least until I could go through all of the gears.

All subsequent rides are the same. Let it idle, ride it briefly with a little choke otherwise it coughs. Slowly go through the first four gears, backing off a little if it slips. Get out onto the highway and ease into 5th and 6th. After about 15 minutes of this I stop worrying because it's much better.

So..
it takes some time and distance to warm up the bike. Even when warm I can't push it hard because it will slip, especially in 5th or 6th. It definitely gets better after warmed up but not perfect.

Is this the nature of the beast or is my clutch going or what?

Thanks for reading my ramblings.

I have an 81 KZ550 and am also a biscuit short of heavy....

I do not experience any "slippy" action in 6th or at higher rpm.
I noticed you said you changed the oil to Penzoil. If you still have the bottle the oil came in check to see if the oil has friction modifiers in it. If so, change it out ASAP. I use Castrol 20W-50 in both my bikes without problems. Some swear by Shell Rotella 15W-40, others swear by lots of other stuff.


There, now I've done it, another oil thread...... :blink:

Oh yeah, the Clymer manual is not the greatest for the 550. Get yourself a factory service manual. You can do a search of the archives here and find "online manuals" there should be a PDF version to download. If not, PM me an address and I'll burn one to disk and send it to you but mine may not cover 83. It's out in the shop so I can't check right now.

Beanie wrote:

... '83 kz550 chain-driven... Clymer manual and adjusted my clutch cable because it felt weird, it took awhile until I realized the manual was backwards... tech said he adjusted the clutch cable. D'oh, I did it wrong... slippy at high rpm... adjusted the cable again. I took it out for a short ride and it felt perfect... next long ride had the same slippiness under load uphill and high rpm... Slowly go through the first four gears, backing off a little if it slips. Get out onto the highway and ease into 5th and 6th... can't push it hard because it will slip, especially in 5th or 6th. It definitely gets better after warmed up but not perfect....

Hello, Beanie, and WELCOME to KZR forum! We're glad you're here!

Althought clutch cable adjustment is mentioned several times in the history, am wondering whether cable pushrod adjustment has also been performed (as direction for turning the pushrod adjustment screw is reportedly backward in some manuals).

The symptom described (slippage under load) is a classic example of improper pushrod adjustment with insufficient gap allowed between the adjustment screw and pushrod when the clutch plates are supposed to be fully engaged.

Regardless of how the cable is adjusted (or even if there's no clutch cable at all), and regardless of the condition of clutch plates (even new clutch plates), and regardless of how strong the clutch springs are and how hard the springs are trying to press the plates together --- none of these elements can overcome lack of the necessary gap, which gap is set by the clutch pushrod adjustment.

Perhaps the tech used the same manual with backward instructions and got it wrong. :lol:

It's easy enough to feel the pushrod gap being closed when squeezing the clutch lever. The initial very slight cable resistance is noticed when taking up the gap, then becomes much more resistant as the clutch plates are separated (disengaged).

Good Luck!

Well if by pushrod you mean the adjusting screw under the small cover on the left side of the engine, then yes, that's what I've been adjusting repeatedly along with the the cable. One concern is the spring that sits on the end of the pushrod lever which the cable slids into might be too weak? The last adjustment I did I was able to push the lever back a bit more than the spring was able to do. That's the setting it's at right now which is giving me the best performance.

As for oil, 10w40 Pennzoil is rated SM and it should be SE. Maybe I need to try a different weight.

I might add that if I have to go from 3rd or higher down to 1st quickly, I can't go past neutral until I released and reengage the clutch.

Beanie wrote:

... One concern is the spring that sits on the end of the pushrod lever which the cable slids into might be too weak? The last adjustment I did I was able to push the lever back a bit more than the spring was able to do....

able to push the lever back a bit more than the spring was able to do. -- Imo, this shouldn't be happening with the new clutch cable unless the cable is binding from being improperly routed.

Good Luck!

If all else fails, try putting eight ounces of Seafoam in the oil and run it 100 miles. Then dump the oil and try standard Castrol GTX 10-40 and see if the slipping stops.

It does sound like maybe the clutch springs are starting to get weak. That's what happened on mine after about 40k miles and the clutch started gradually slipping worse and worse.

Let's say the handlebar clutch lever is squeezed against the handlebar grip, and is now being gradually released, as in the normal procedure whereby the clutch springs are gradually allowed to press and hold the clutch plates together (thereby engaging the clutch).

At some point during gradual release of the handlebar clutch lever, the clutch pushrod "gap" is encountered, whereby the clutch springs are holding the clutch plates together as tightly as possible, regardless of remaining cable movement from that point until the handlebar lever fully returns to its normal unsqueezed position.

Upon encountering the pushrod gap, the clutch springs and plates have no more effect toward moving the cable. At that stage, the small spring located just under the engine cover is supposed to provide enough pressure to return the cable to its normal "unsqueezed" position at the handlebar. And will readily do so where the inner cable is sliding smoothly within the outer cable sheath. Which requires that the inner cable be capable of easily and smoothly moving within the outer cable sheath, lubed and not frayed, and with the cable routed so it's not binding.

Imo, if the gap is there, and the clutch continues slippimg under load with proper motor oil in the crankcase, the springs may be weak and/or clutch plates worn or glazed, or some other abnormality exists within the clutch basket assembly.

Good Luck!

I had to read that real slowly to fully comprehend what you said.. lol. I'm now 100% sure it's not the cable and 99% sure it's not the pushrod.

I was looking through the oils in Walmart yesterday and couldn't find anything less than SL rated, including the Castrol GTX. Are you sure about that Castrol?

I'm using Pennzoil(SAE 10W40),and I'm having no problems with my clutch.
But I'm also using A.P.E. heavy-duty clutch springs with my engine set-up,as recommended.

I know that when I first put this together,it was slipping at hard pulls,or higher rpm's,and after adjusting the screw for the pushrod,I DID get it perfect.
Been working great ever since now,for a few years.

Well if it's a case of installing HD springs I might as well replace the clutch pack.

Keep in mind this bike is new to me. The mileage is unknown because the speedo wasn't original. It may very well be time for a new clutch.

Where's a good place to get the discs? And what are other's opinions on putting in stronger springs?

You will look long and hard for an SE rated oil in Walmart or any auto store. That rating was superseded a long time ago. The closest I can find are SH rated. Now most auto oils are at least SL-SM rated.

By the way, the Pepboys near me just started carrying Castrol 4T bike oil for a good price, under $4/qt. That's the next stuff I'll buy as it's SG rated.

My 650 calls for SE oil, but I have used Castrol GTX auto oil 10w-40 and 20w-50 for most of the time, with a few changes using Shell Rotella Diesel 15w-40, and another semi synthetic blend twice, I think Valvoline. The engine seemed to run fine with them, but the Rotella lost the smooth shifting the quickest.

Right now I have Kawasaki brand 10w-40, I think it's SH rated and it has never shifted better, so at $4.25/qt I'll stick with it. I think the closer I can get to SE the better.

It does sound like clutch springs. Just replace them, no need for HD springs unless you like to give your left hand a work out.
You would be surprised how long the clutch plates last.
New springs are about $15 from z1e.