76 KZ750 hard to/can't start

I bought my first bike a week ago, a 1976 KZ750. I drove it the 100 miles home all right. It would only start after wresting with the kickstart usually. Eventually learned to push start it when I was tired from kickstarting.

Couple days later I put in 2 new spark plugs, caps, battery and run some Seafoam through the tank and it now starts most the time with the electric start or the kick if it had been a while.

Hour or so after getting home from work couple days ago I tried to start it and it just refused. Starting with the button makes a metal grinding/metal sliding noise, and kick starting is so hard the pedal wont budge half the time, and still wont start it. Tried to push start it but now the clutch is partially engaging and I don't have the strength to push it let alone pop start it.

Here's a video of me trying to start it couple days ago.

video.google.com/videoplay?docid=4247130303141479677

I got a response in another forum that my starter clutch is bad. I downloaded a manual for the bike, disconnected the battery and plugs, took apart the dynamo cover and used a ratchet to turn the dynamo counterclockwise slowly. The sprocket and chain turned with it. Turning it slowly clockwise they do not.

What can I try next?

Are the battery connections clean and tight to both the frame/engine and to the starter solenoid?(follow the positive terminal from the battery to a small round device with two small wires and two large terminals).

Clean all electrical terminals of the green crud of corrosion(bullet connectors and square and rectangular connectors,fuse clips and handle bar switches.

Give the above a try and lets us know how it's going.

check to see if it's getting fuel, sounds like it's not, the starter clutch goes bad in a lot of the twins, mine doesen't work so I kick it always

I looked (and listened) at the video, and that doesn't sound like the usual bad starter clutch on a 750 twin. Pull the alternator cover off and look, it sounds like the chain has jumped off the starter clutch sprocket and is chewing up the inside. I have seen this once before on a 77 KZ750B.

Battery connections are good. As for fuel, I know there's gas in the tank and the petcock is on. How far down from there it's getting I don't know. Like I said, it was just running fine couple hours before making the first video.

I've pulled off the cover and looked at the dynamo, sprocket and chain. It looks ok to me, but I haven't taken it any farther apart than the cover. The chain is on the sprockets and it turned with turning the rotor the way the manual says it should.

Today I just took a video of me actually cranking up the electric start with the cover open to see what's happening and it looks to me like it's supposedly working right. I hit the button and the starter turns the chain and the chain turns the rotor. I've taken out the plugs and I can feel puffs of air shooting out the plug holes while it turns over.

video.google.com/videoplay?docid=4480870212849256231&hl=en

I had a mild oil leak under the engine before now so I want to try to find a new gasket before I replace the cover and I had to drill out one of the cover screws so I have a little work to do before putting it back together but otherwise I'm not sure what could be keeping this from starting.

As for kickstarting it, if you look at the first video, about every other attempt to kick it over I just simply bounce off the pedal and give myself a hernia. I weigh 200 pounds and 50% of the time I can't get the kicker to drop. Even when I do, it's fairly rare to get the bike to start up that way, I usually end up pushstarting it if I can't get the electric start to work.

As for the clutch not fully releasing, I read in some other threads here that sometimes getting the engine to start will fix that problem, so for now I'm focused on that. Steell I have adjusted the play out of the cable according to the manual and it still wont fully go away. Judging by how that problem just mysteriously showed up at the same time this starting problem did I'm hoping that problem fixes itself.

What is the spark quality when spinning the engine over with the plugs removed?

Sorry for arriving late to the party...

...but yeah, that is pretty much the same as has happened to 3 out of 4 of my bikes. Typical starter clutch failure. Dead. Done. Toast. Needs repair or elimination/removal....

First, see [url=http://kzrider.com/index.php?option=com_kunena&Itemid=107&func=view&id=149604&catid=2
]my old thread for reference[/url]...

I'm one of those that hates the starter clutch, and I'm glad to be rid of them (to differing degrees) in my two 750s. Mine totally failed, but they sounded like yours before they gave up the ghost.

Also, I'm about 220 lbs, and like steell, my bikes usually kick over in one or two (okay, maybe three after a week) kicks...

Regarding the kickstart, yes, it has big ol' cylinders with somewhat high compression. Who knows, you could have zero valve clearance or something that could make it harder to start... you get to check that next...

While the cover was removed as during the second video I watched a plug as I turned it over and saw no spark, but I thought maybe since I had the rotor cover off and the windings were laying on the floor that's why. I haven't checked the spark on it assembled yet.

Biquetoast did you see the second video in the last post? It shows the starter clutch turning the rotor when I hit the starter. Does that not mean it's doing what it's supposed to do?

Ashbane wrote:

While the cover was removed as during
the second video I watched a plug as I turned
it over and saw no spark, but I thought maybe
since I had the rotor cover off and the windings
were laying on the floor that's why. I haven't
checked the spark on it assembled yet....

With good fully charged battery,
should see good spark quality on
plugs without dynamo, rectifier
or regulator (i.e., running a
"total loss" system from power
in the battery), and run just fine
until the battery gets weak.
The dynamo, rectifier and regulator
serve to keep the battery charged.
The coil draws power from the battery -- not
from the dynamo, rectifier and regulator.

Am thinking the problem may be in
the ignition system (after the battery --
not before the battery).

Need to be seeing a good
spark on the plugs.

Good Luck!

Ashbane wrote:

...Biquetoast did you see the second video in the last post? It shows the starter clutch turning the rotor when I hit the starter. Does that not mean it's doing what it's supposed to do?

Garsh... I had missed that... you're right, the sprocket appears to be locking against the starter clutch and rotor, and turning it. Sorry I missed that. :blush:

I was just going by the sound from the first vid. The sound was like a dead starter clutch. I mean, it *really* sounded like it was slipping. In fact, it might have been, and once you remove the plugs, there is significantly less resistance since there is no compression...

Ok I FINALLY got the rotor off and examined the clutch. I don't have my metric allens so here's the pics of the clutch while still attached to the rotor. They 'seem' ok to me other than a couple very small scratches. I was also able to push each roller up and down in their slots with my finger easily.

And you're right Biquetoast, when I first heard the sound of the electric start when it didn't fire up the engine it sounds exactly like metal dragging around inside the case. But now that I got it open and looked at I'm wondering if there isn't something else that not only keeping the electric start from starting it but also the kick. Like I been saying all along, this thing was easier to push start than kick over. It's a friggin MULE to kick over and I haven't had any more luck starting it that way than with the electric.

Also, I took a pic of the plugs I just bought 3 days before tearing this all apart.









Also found a possible reason for a small mystery oil leak....

Hmm. So the starter clutch "looks" fine, and that's good. Stick your fingers in there and feel to see if the springs (behind the rollers) still push back on the rollers, and they roll smoothly.

But the wear (that would cause it to not grab) could really be on the starter sprocket. I've read somebody put it on a lathe and cleaned up the surface to repair it.

I'm not sure that little jbweld part is causing an oil leak. It looks like there's good metal around it. The leak would more likely be from a bad (or re-used) gasket.

How about this... when you get it back together and the cover is still off, put your plugs back in and hit the starter button. With the additional compression we can see if the clutch slips...