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Z2 750 crank (Bossie the Kaw) 15 Sep 2015 09:25 #690168

  • missionkz
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Are you cracking and replacing the crank and rods???
Bruce
1977 KZ1000A1
2016 Triumph T120 Bonneville
Far North East Metro Denver Colorado

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Z2 750 crank (Bossie the Kaw) 15 Sep 2015 10:48 #690190

  • SWest
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No, just switching pistons. It's been a nagging question for a year now. Had some lunch and a short nap. Time to finish tearing it down and some pics.
Steve
Z1b1000 1975 Z1b
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kzrider.com/forum/11-projects/598262-kz-...-will-it-live#672882
kzrider.com/forum/2-engine/597654-poser?start=240#704229

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Z2 750 crank (Bossie the Kaw) 15 Sep 2015 13:55 #690209

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DAMAGE; I've been saying the manual adjusters are dangerous. Here's why.




I got it too tight and destroyed the center rubber roller and the front guide. As the chain became noisy, I kept adjusting it. Good thing I bought some extra parts and decided to do this. :dry:


The 903 block is in front. The 903 gasket worked just fine.


Here's the deck height.






2,5mm below the deck.




Home made tool for removing pistons.




Talking the head inside for cleaning and honeing the cylinders.
Had a broken ring on #4 piston. No damage.
Steve
Z1b1000 1975 Z1b
Opinions expressed by me do not reflect those of the the staff or members
kzrider.com/forum/11-projects/598262-kz-...-will-it-live#672882
kzrider.com/forum/2-engine/597654-poser?start=240#704229

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Last edit: by SWest.

Z2 750 crank (Bossie the Kaw) 15 Sep 2015 15:23 #690226

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Yikes!! Did you find any of the rubber and dampening material junk in the oil or stuck in the pickup screen. I did, many years ago, in my 77' KZ1000. It had crap in the oil that I found was material worn off the wheel and front slider guide!! I was forced to do the same as you and I've never used a manual chain tensioner.
Bruce
1977 KZ1000A1
2016 Triumph T120 Bonneville
Far North East Metro Denver Colorado

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Z2 750 crank (Bossie the Kaw) 15 Sep 2015 15:38 #690231

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I still have my spring loaded tensioner. I'm tempted to put it back on. If my chain had broken, it would have made for one FK'ED UP DAY. :ohmy: It's ironic I was warning about them and here is the perfect example.
You can see the number 45 stamped on the crank. Before I button it up I'll measure the rods. 2.5mm is a lot. No wonder I had low compression. If I lose cc's, so FKing what. That would mean it IS a 750 crank and should spin faster as planned. I'll take more pics tomorrow.
Steve
Z1b1000 1975 Z1b
Opinions expressed by me do not reflect those of the the staff or members
kzrider.com/forum/11-projects/598262-kz-...-will-it-live#672882
kzrider.com/forum/2-engine/597654-poser?start=240#704229

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Last edit: by SWest.

Z2 750 crank (Bossie the Kaw) 15 Sep 2015 16:20 #690244

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i was right you had a low compresion POS
original owner of a 1984 gpz 750
1985 turbo 750 stock, being restored.
1984 gpz 750 with 810 cc wiesco's megacycle cams(471-10) 34 mm flatslides v&h pipe ported head dyna ignition. bottom end, crank case from turbo 750 and sprockets.

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Z2 750 crank (Bossie the Kaw) 15 Sep 2015 17:08 #690247

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I expected that. :lol:
Steve
Z1b1000 1975 Z1b
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kzrider.com/forum/11-projects/598262-kz-...-will-it-live#672882
kzrider.com/forum/2-engine/597654-poser?start=240#704229

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Z2 750 crank (Bossie the Kaw) 16 Sep 2015 01:13 #690281

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looks like you need a valve job i would send it out and have new viton seals put in .one of the cylinders looks pretty scored up time for a rebore.take some more pics so we can see how bad the cylinder is do you have a dial bore gauge to measure the tapper ? and take a valve out so we can see how bad the seats are.
original owner of a 1984 gpz 750
1985 turbo 750 stock, being restored.
1984 gpz 750 with 810 cc wiesco's megacycle cams(471-10) 34 mm flatslides v&h pipe ported head dyna ignition. bottom end, crank case from turbo 750 and sprockets.

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Z2 750 crank (Bossie the Kaw) 16 Sep 2015 03:21 #690289

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I have no interest in YOUR opinion or anything you can dig out of a book. :lol: Valves done last year. For everyone else.
Kibblewhite valve springs, new valve guide seals, new Dorimi valves. More pics to come. B)
kzrider.com/forum/2-engine/596420-valves#653678
Steve
















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Last edit: by SWest.

Z2 750 crank (Bossie the Kaw) 16 Sep 2015 04:49 #690300

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Bruce, you're right. I'll need to drop the pan and clean out all the junk on the strainer. When I did my oil change a small piece of plastic came out. It was from the cam chain sprocket. 40 years old so I wasn't alarmed, now I am'. Everything is cleaned up and I will put it back together today. Still have to take pics of the rings and if they migrated or not :whistle: , more of the crank, the hone job, etc. There always has to be a snag and I was prepared for it. B)
Steve
Z1b1000 1975 Z1b
Opinions expressed by me do not reflect those of the the staff or members
kzrider.com/forum/11-projects/598262-kz-...-will-it-live#672882
kzrider.com/forum/2-engine/597654-poser?start=240#704229

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Z2 750 crank (Bossie the Kaw) 16 Sep 2015 09:07 #690319

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I took some pics of the rings. They migrated quite a bit. Not close to where they were set.






Head cleaned up, painted and ready to go.


Some pics of the crank and rods. The only place you can see where it was welded is the center pin. I'll also jot down the markings on the rods. You can barely see them.










Steve
Z1b1000 1975 Z1b
Opinions expressed by me do not reflect those of the the staff or members
kzrider.com/forum/11-projects/598262-kz-...-will-it-live#672882
kzrider.com/forum/2-engine/597654-poser?start=240#704229

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Z2 750 crank (Bossie the Kaw) 16 Sep 2015 09:18 #690321

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Interesting looking below the rings where the oil has been burning, and how it differs slightly between pistons. Looks to me like they were past their best.

I'm thinking now the most critical thing for good ring seating is the cross hatch hone, I have a honing tool taht I've used in the past but In future I'll leave it to a pro..
1980 Gpz550 D1, 1981 GPz550 D1. 1982 GPz750R1. 1983 z1000R R2. all four aces

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