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Burt Munro Is My Hero
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Discussion Starter · #1 ·
Hey everyone, I find myself in need of help from the hive mind. Here's the story:

Last summer after battling to get my 1978 Kawasaki KZ750 Twin (B3) up and running in the spring, I rode blissfully until July, at which time it started acting up and refused to start, I fiddled with the points and condensers and the timing and went to check compression only to find the starter spun like a top without engaging. D'oh. I've become accustomed to kick starting the bike as it seems to like that better. About that time I had to head out to Bonneville for speed week. (You can read more about that here (I'm Ben))

When I returned, much to my horror, my baby was lying on her side and had been for what looked like a while. The asphalt had melted under the center stand and you know the rest of the story. The most distressing damage came from the clubman bars slowly rotating under the weight and putting a healthy ding in the tank, yarg. Needless to say, a week on its side didn't help the starting situation and I couldn't make enough time to properly go through her. As fall turned to winter, I made space in my kitchen and brought her inside, intending to go through all the major problems and address all the little maintenance items I've been putting off (fork seals, fork oil, spit shine, etc. )

So, here I am after the shenanigans of the holidays are over and I now have time, having removed both the sprocket guard and the starter cover/dynamo cover, removed and tested the starter and I am unable to get the flywheel off to get to the starter clutch because I don't have the correct tool. It's basically a spanner wrench that hooks up to two studs you bolt-clamp into holes on the flywheel, at least that's what it looks like. These things aren't exactly a dime a dozen and I don't believe you can buy them at the dealer anymore (will be calling in the morning). I've included a picture which has the tool number of the spanner required for this and I'm hoping someone either knows a source, knows how to work around this or knows someone who knows someone who'll part with or loan out theirs.

As you might imagine, this is just step one on the late-winter refurbish, so I'm sure this thread will have more "help I've hit a roadblock" moments.
 

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This space for rent
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687 Posts
I have never seen that special tool, but I have removed the rotor from 750 twins a few times (650 and 750 fours as well).

I know for a fact that the rear axle will fit, and I've been told that the chrome bolt in the middle of the steering stem will work. You need to screw it (axle or steering stem bolt) into the rotor just as tight as you can get it, then give the end of the axle/bolt a good healthy whack with a good size hammer (3 lb works nice). That should pop the rotor right off since it's just a taper fit, if not then do it again.


By the way, that pic just shows the rotor bolt being removed, the threads used to remove the rotor are normal right hand threads, the bolt that holds the rotor on is a left hand thread.
 

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Burt Munro Is My Hero
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665 Posts
Discussion Starter · #3 ·
I have never seen that special tool, but I have removed the rotor from 750 twins a few times (650 and 750 fours as well).

I know for a fact that the rear axle will fit, and I've been told that the chrome bolt in the middle of the steering stem will work. You need to screw it (axle or steering stem bolt) into the rotor just as tight as you can get it, then give the end of the axle/bolt a good healthy whack with a good size hammer (3 lb works nice). That should pop the rotor right off since it's just a taper fit, if not then do it again.


By the way, that pic just shows the rotor bolt being removed, the threads used to remove the rotor are normal right hand threads, the bolt that holds the rotor on is a left hand thread.
I don't really understand this response at all. I'm not trying to remove the rear rotor, I'm removing the flywheel.

Though, I suppose it's possible to crank the rear axle down so tight that if I put the transmission in gear I could conceivably remove the flywheel, but that's a lot of stress through a lot of drivetrain I'm not interested in applying.
 

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This space for rent
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I seem to have a problem communicating my ideas, you're not the first to mention it.

Take the rear axle out of the rear wheel, screw it into the alternator rotor (the thing you're trying to remove) as tight as you can get it. Smack the end of the axle one time really hard, like you're trying to drive the axle through the crank. The alternator rotor (what you are calling the flywheel) should pop right off.

I believe you think the alternator rotor is on a straight shaft and has to be pulled all the way off. It's not. The crankshaft has a taper and the alternator rotor slides on that taper. If you move the alternator 0.0005" toward the outside it will become totally loose.

Is that better?


Edit:

Have you taken a close look at the alternator rotor? The bolt that you see in the picture screws into the end of the crankshaft. The alternator rotor (I'm going back to calling it a rotor) does not slide all the way on the crankshaft, the crankshaft is about 3/4" or so down in the hole. The inside of the rotor is threaded, so you screw the axle into those threads until it bottoms out against the crank.

Am I doing any better? :)
 

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Burt Munro Is My Hero
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665 Posts
Discussion Starter · #5 ·
The 1978 design is simplified and doesn't have an alternator rotor. As you can see in the below diagram, the part I'm trying to get off is referred to as the "Dynamo Flywheel" (#21) in the second diagram. I'm trying to get to part #15 the starter motor clutch.


The trouble is not in removing the flywheel from the tapered shaft (yet), it's holding the flywheel in place so I can remove the bolt from the crankshaft.
 

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This space for rent
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There's that communication thing again, see, I just can't imagine anyone having a problem getting that bolt off, even without access to air operated tools.

Put the longest wrench you have on that bolt and smack it with the big hammer referenced earlier. Just be sure to turn that bolt clockwise to loosen.

A KZ750 Twin manual printed using the Queens English (dynamo is an English UK term), does it mention gudgeon pins in it? :D

Let me guess, that a Haynes manual??


Edit:

I've been answering questions about the KZ650 and 750 fours, and the KZ750 twins, since sometime in 2003. Starting at kzrider.com until I got ripped off for $300 by one of their star members, then THE KAWASAKI TWIN OWNERS FORUM :: Index whenever a question attracts my interest, and here. And this is the first time I have heard of anyone having a problem getting that bolt out (aside from turning it the wrong way). So I think my confusion is understandable :)

Check out http://kz750twins.com/ for a downloadable Factory Service Manual, plenty of other 750 twin info there also.
 

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Navy Vet Search & Rescue
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A KZ750 Twin manual printed using the Queens English (dynamo is an English UK term), does it mention gudgeon pins in it? :D

Let me guess, that a Haynes manual??
I started wondering what the source of his manual was as soon as I read the word dynamo. I have to admit and ask at the same time, what is a gudgeon? That's a new one on me. :lol:
 

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itching to ride
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2,233 Posts
Like steell said, a good rap on the wrench should loosen the bolt. Just remember it is a left-handed thread so it turns the opposite direction as a normal bolt.
 

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This space for rent
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I started wondering what the source of his manual was as soon as I read the word dynamo. I have to admit and ask at the same time, what is a gudgeon? That's a new one on me. :lol:
Gudgeon pin is what we in the US call a wrist pin, or piston pin.

I lived in the UK for 3 years in a former life, the only foreign language I speak is the Queen's English :lol:
 

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Navy Vet Search & Rescue
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Well you did better than I did. I lived in Japan for 2 years and only learned a few common phrases and words and to count to 10. :lol:
 

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Burt Munro Is My Hero
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665 Posts
Discussion Starter · #12 ·
Kawasaki factory service manual printed right in Japan, part number 99997-744-03

It's not an issue of torque, I'm pretty sure I've got a big enough lever, it's a matter of restraining the crankshaft, the thing just turns when I try to loosen the bolt. I did try your "put a big wrench on it and whack it with a hammer" method to no avail though.
 

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have you considered a air impact wrench?
i ork on alot of cars,the harmonic balancer bolt on the crank is usualy very tight.
procedure calls for jamming the flywheel with a large screw driver or a pry bar.
i just use my impact to bust it loose,im careful not to spin the engine with the impact wrench though.
ive never tried this on a bike.
 

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Navy Vet Search & Rescue
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If all else fails and you can't come up with the special tool, you could always use a strap or chain wrench to hold it. Either one would probably do the job and they're pretty common.
 

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Navy Vet Search & Rescue
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Yep. Officially we were assigned to NAS Atsugi. But we also went to sea with the USS Midway as a detachment each time it pulled out. We were the ships only rescue resource at sea for man overboard or downed pilots.
 

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itching to ride
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2,233 Posts
have you considered a air impact wrench?
i ork on alot of cars,the harmonic balancer bolt on the crank is usualy very tight.
procedure calls for jamming the flywheel with a large screw driver or a pry bar.
i just use my impact to bust it loose,im careful not to spin the engine with the impact wrench though.
ive never tried this on a bike.
An impact works well for this and I have even put the bike in gear and blocked the wheel from turning with a bar to break a bolt loose.
 

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Machinist For Sale/Rent
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1,234 Posts
<------If all else fails; measure the diameter of that rotor/flywheel you are trying to remove. I can and will make the tool you need to get it off, I also need to know exactly what the thread is in the side of the rotor where you screw that anchor bolt.
 

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Burt Munro Is My Hero
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665 Posts
Discussion Starter · #19 ·
Well things got delayed on this project, I bought a house so that's been consuming some time. On the plus side I've moved out of the kitchen and into a proper garage.

I did manage to snag an electric impact wrench and now all my bellyaching about getting that bolt off seems silly. I have also taken steell's advice and I'm attempting to use the rear axle as a flywheel puller, seems like it'll work, but the "wack it with a big hammer" approach doesn't seem to be having a positive effect. If I were able to keep turning it the thing would pop off and if I had a big weight on it like an dent puller it might work, but who knows.

Any advice?

Also, a guy can never have enough projects:
 

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Burt Munro Is My Hero
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665 Posts
Discussion Starter · #20 ·
As an aside, I'm having my brother work on a "government project" at his work that looks a whole lot like the factory flywheel wrench, so this will be a moot point in a few weeks.
 
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