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TOPIC: Z2 750 crank (Bossie the Kaw)

Z2 750 crank (Bossie the Kaw) 17 Apr 2015 04:45 #668335

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Hmmm, he states the connecting rods are shorter on the Z2. I was expecting them to be longer. Not the first time I've been wrong.
Current project 76 KZ900 (This was a Vetter model)
76 KZ900
81 XJ550H SECA (Current Project)
82 XJ550R SECA
Past:
86 FJ1200
74 Z1900
72 CB450

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Z2 750 crank (Bossie the Kaw) 17 Apr 2015 05:22 #668338

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I was checking the sizes of the 903,1015 pistons cast and billet against the 750 piston. I just came up with more questions. I applied to the Z2 site, we'll see if I'm accepted. Maybe then I can get info from some of their members. I'll post pics of the pistons and my measurements with my caliper later today.
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) 19 Apr 2015 16:23 #668758

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A coat hanger, or any straight piece of wire can answer the question. Pull the spark plug, put the piston at BDC, measure how far the wire comes up the plug hole for the piston to reach TDC. I would think the 903 Z1 could have been made into the 750 Z2 CHEAPEST by pushing out the 903 sleeves from their cylinder block, pressing smaller bore/thicker wall sleeves with the desired bore for the 750, changing the pistons, crank, and rods.

Should take about two minutes to end this argument.


I have a Ford 352 (FE series engine) that is the same as the famous 390 other than rotating assembly. Ford didn't mark the engines well, so the easiest way to know what you (should) have when you deal with the FE is to measure the stroke.

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Z2 750 crank (Bossie the Kaw) 19 Apr 2015 18:09 #668775

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No arguement. I have a 903 piston and two different Wiseco 10.25/1 70mm pistons. I've measured them and will put up the comparisons to the 750 soon. The blocks are the same. It appears The pistons and crank are different. I'm in no hurry.
Steve
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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) 19 Apr 2015 20:06 #668794

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Below is a stock KL250 piston (with rings) and a Wiseco 1075cc 72mm piston. With a standard 17mm pin pushed through both pistons, you can see the Wiseco is about .025"-.035" taller then the KL250,
That means it will go into the combustion chamber further and it not be at flat deck height in a stock block.
Not sure what that means or how it connects with what your talking about ... but there you go...



Bruce
1977 KZ1000A1
2016 Triumph T120 Bonneville
Far North East Metro Denver Colorado
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Last edit: by missionkz. Reason: trying to revole the image....

Z2 750 crank (Bossie the Kaw) 19 Apr 2015 20:12 #668796

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My camera won't work without full batteries. I'll put up pics as soon as I cam. We're talking about 8mm here.
Steve
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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) 19 Apr 2015 20:15 #668799

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Yikes, that is 5/16".....
Bruce
1977 KZ1000A1
2016 Triumph T120 Bonneville
Far North East Metro Denver Colorado

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Z2 750 crank (Bossie the Kaw) 19 Apr 2015 20:19 #668804

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Now that's about as low in the cylinder the stock 1015 pistons are. Not 8mm.
Steve
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Z2 750 crank (Bossie the Kaw) 28 Apr 2015 17:53 #669915

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hows that z2 crank doing in your 892 cc motor?
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) 02 May 2015 10:20 #670383

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i am still trying to piece this engine combo out .when you have a short stroke low compression motor how can it make the same horse power? and the jetting has to be different.i wish i knew the answer.
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) 02 May 2015 19:38 #670456

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Two foregoing posts moved from Carburetor forum.

Good Fortune! :)
1973 Z1
KZ900 LTD
The following user(s) said Thank You: SWest

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Last edit: by Patton.

Z2 750 crank (Bossie the Kaw) 21 Jun 2015 15:25 #677628

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Won't be long now. I just ordered my piston and base gasket. Still need a one piece copper head gasket. One thing at a time.
Steve



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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
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Last edit: by SWest. Reason: add

Z2 750 crank (Bossie the Kaw) 11 Jul 2015 07:18 #680360

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i was talking to my friend Wes at cycle rama and he said the z1 900 cc cranks were the lightest of the kz motors .i would put a welded z1 crank back in there and run your 1015 cc pistons with composite head gasket.it will make a big difference.
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) 11 Jul 2015 07:51 #680362

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It remains to be seen if in fact is is a 750 crank or a 903 crank. That was back in 87 and to be honest, I'm not sure if I tried to use the 750 or decided to use the 903 I already had. I do know I had a crank in the shop wrapped in double trash bags that was ruined in the fire. Clupper Racing had the one that's in the bike welded for me by V/H, I know that. They also bored out the 750 sleeves. I remember that because they complained about them spinning in the barrels. I just got back from Oregon where it didn't go well for my daughter. Once again I will still have to wait to buy a head gasket and a few supplies. Back to work. Once I open it up it will be apparent as to what it actually is. From what I've been able to find out to this point, the wrist pin is off 2mm and the crown is 10mm. A big difference to the stock 903 or 1015 pistons. If the deck height is 2mm lower like I think it is, I'll keep the 750 crank. We'll see.
Steve
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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 08:56 #690162

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The weather will be cooler this week, I have what I need and time, I have no excuse not to do it. Everything looks good going in.




I knew reusing the rings would be iffey and it was burning a small amount of oil. Not bad after two years. The stock 1015-8.5/1 pistons are pretty clean comparitivly. #2 was burning the most oil as seen by the clean ring around the outside top of the piston. Time to stop, take a break, then go out and measure the deck height.




I know I was running low compression. Now we'll see why. Some light scuffing on the bores. Probably missed crap from when I did my valves.


I'm going to take pics of the caliper, then the crank rods and whatever marking on the crank throws.
Steve
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Z2 750 crank (Bossie the Kaw) 15 Sep 2015 09:03 #690165

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Oh, that funky fuel filter? That's what Z1E sent me. Not what I wanted. Too big and I broke the other one last year. I replaced it and have a new one to boot this one off the bike.
Steve

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kzrider.com/forum/11-projects/598262-kz-...-will-it-live#672882
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Z2 750 crank (Bossie the Kaw) 15 Sep 2015 09:25 #690168

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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

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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
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kzrider.com/forum/11-projects/598262-kz-...-will-it-live#672882
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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
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kzrider.com/forum/11-projects/598262-kz-...-will-it-live#672882
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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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