Starter Clutches and OIl

I recently purchased an 81 750 LTD at a yard sale for $150. The bike had set without running for years. It now runs great and is silly, stupid fast! The biggest problem I have had with it is the infamous Kaw starter clutch slippage. My mechanic, who got just whirring noises and rare or no engine turnover, insisted that the only fix was to split the case and install a new starter clutch. Since this is my first post, I hope I can make a positive difference for you old timers.

I did not want to spend $600 on labor on a cheap bike, so I did several Google searches on the issue and tried what the consensus in the riding community recommended.

(Disclosure: I have no connection whatsoever with any oil company).
To cut to the chase, I believe that most, if not all Kawasaki starter clutch issues are caused by using an automotive grade oil with friction inhibiters (Which was not available widely when these bikes were new). On a Kaw, the starter clutch, like the main clutch, is submerged in oil. Modern Automotive SJ rated oils all contain friction inhibitors, the bane of both motorcycle clutches and starter clutches. I have kept careful notes on the oils that I have used, since I have changed the oil numerous (5) times since my purchase, believing that the wrong oil is almost always the real culprit. After much trial and error, I have concluded that Shell Rotella T 5-40 synthetic Diesel truck oil works miracles for the Kaw starter clutch and makes it shift better to boot! For three reasons: Rotella is a very high detergent oil that cannot be used in modern automobiles because it's high phosphorus (detergent) content messes with catalytic converters (but cleans out all the gunk and rust from years of sitting) and 2) it contains no friction inhibiters 3) it is sythetic so allows easier cold engine turnover.
My 750 now starts and engages like a new one, and this morning it was cold enough to have frost on my car windows. It started and purred after three stabs on the button. It only "whirs" without engaging very rarely now, usually only when I press the button and hold it down. I tried the following motor oils before settling on Rotella syn, the worst being 20-50 dino Supertech (from Wallyworld) and the second best being Chevron Delo 15-40 which works almost as well as the Rotella synthetic. Mobil 1 5-30 syn rarely allowed full engagement, making it nearly as bad as Supertech. Dino 10-40 from NAPA was right in the middle, while Supertech 5-30 dyno was also right in the middle as far as starter clutch usability.

So until you have drained your crankcase of all that low friction automotive oil DONT SPLIT YOUR CASE!, save yourself a major headache by changing your oil to either a motorcycle-exclusive oil (damned expensive) or one of the Heavy Duty high-detergent Diesel oils like Delo, Delvach or Rotella.

There you have it! Enjoy!

Post edited by: Larry P2, at: 2006/10/03 17:16

I use this
SAE 20w50

Welcome aboard, Larry.

Just for the record: your mechanic is wrong, on the 650s/750 fours you don´t need to split the cases to remove the starter clutch - actually it´s the other way around, you need to remove the starter clutch/secondary shaft to split the cases. The secondary shaft which also holds the starter clutch sits in the lower case half only and is tied to the crank through the primary chain, with the shaft in place you can´t pull the case halves apart.

I don't know. We've talked about this here a few times. You may not have to actually split the cases to work on the starter clutch, as guys have done it here, but it's not an easy job to say the least whichever way you plan to do it. According to all manuals written, the cases need to be split to work on the clutch, and is the way I've always done it. No matter what, the engine needs to be removed from the frame to do this job.
I will never believe a different type of oil will have any effect whatsoever on the starter clutch as these caused a lot of problems 30 yrs ago and still cause a lot of problems today none of which relate to the oil. It's a mechanical thing, it doesn't know or care if the oil has friction modifiers in it.

Well I can tell you first hand you dont need to split the cases or remove the engine. Did mine about a year ago and only needed to remove the clutch and clutch basket to get to everthing I needed to drop the secondary shaft out the bottom. I think it took me about 4-5 hrs total with breaks. The only thing that made it difficult was removing the nut on the clutch basket. Definately need a impact wrench for that. And by the way, I followed the instructions in the manual.

750LTDRider wrote:

Well I can tell you first hand you dont need to split the cases or remove the engine. Did mine about a year ago and only needed to remove the clutch and clutch basket to get to everthing I needed to drop the secondary shaft out the bottom. I think it took me about 4-5 hrs total with breaks. The only thing that made it difficult was removing the nut on the clutch basket. Definately need a impact wrench for that. And by the way, I followed the instructions in the manual.

I'd have to see this first hand. Next time I need work, I'll let you do mine :ohmy:

I´ll repeat myself: you CAN NOT pull the engine cases apart on a 650/750 four without first removing the secondary shaft, it´s physically impossible, the primary chain goes around both the crank and the secondary shaft. And the starter clutch sits on the secondary shaft with the primary chain around it so you have to remove that too. To remove the secondary shaft/starter clutch you first need to remove the clutch, clutch basket and clutch hub to gain access to the secondary shaft bearing bracket which also needs to come off, then you can remove the oil pump. After that you remove the bearing cap on the opposite side of the engine and tap out the shaft. Here´s a pic looking up a 650 SR engine with the oil pan and oil pump removed, you can see the secondary shaft, the starter clutch housing and the primary chain (arrow).



Post edited by: OnkelB, at: 2006/10/04 14:03

In this pic the secondary shaft is tapped out and you can now remove the starter clutch housing from the primary chain.

And finally a pic of the secondary shaft and starter clutch removed from the engine, cases still together. At this point, and at this point only, is it possible to split the cases. Believe me, I have done it twice.




For those of you with sharp eyes: yeah, you need to remove the transmission cover too before you can pull the cases apart, just noticed it wasn´t off yet.

:whistle:

Post edited by: OnkelB, at: 2006/10/04 10:56

OnkelB wrote:

I´ll repeat myself: you CAN NOT pull the engine cases apart on a 650/750 four without first removing the secondary shaft, it´s physically impossible..

Ok, I guess this statement is only partially true as it might be possible to remove the complete topend (head, cylinders and pistons) and pull the top case off the lower case leaving the crank sitting in the lower case, but you would still need to remove the secondary shaft/starter clutch to separate the crank from the lower case. And no matter which way you go, the secondary shaft needs to come out if you want access to the starter clutch internals, no way around that.

Post edited by: OnkelB, at: 2006/10/04 11:07

Yes I do understand that Kaws have had the starter clutch problem for 30 years. But there is no question that motor oil has gone through a dramatic transformation in the last 10 years, and the right oil will either eliminate or drastically improve even a bad starter clutch.
But Hey, if you wanna pull the engine and do all that open heart surgery, then have a party. But for some of us, that kind of stuff is pretty much out of reach, which is why I read the internet and why I have changed the oil five times on a bike that was purchased on August 1, 2006. There is a lot of stuff on the internet RE: slipping starter clutches and the wonders that can be had with a simple oil change.
And just last night, I stole ($200) a gorgeous low mileage cosmetically perfect Yamaha 400 special with ..... you guessed it, a starter that whirs but does not engage.

Any takers out there willing to bet one way or another that Rotella wont fix this thing?

Post edited by: Larry P2, at: 2006/10/04 12:45

Well I can tell you oil wont always fix it. On mine it was actually bad. The screws holding the clutch together actually had come loose and caused severe wear to the clutch. I always used the same oil in mine and it just got worse and worse until the only option was to push start it. And this was only over the course of about 6 months. But I do hope beter oil will fix it for you. I can tell you with my new clutch, I have been running automotive oil and I have not had a slip yet. The friction modifiers are only found in 10W-30 and 5W-30 oils from what Ive read. using 10W-40 or 20W-50 is fine in the bike.