Welcome, Guest
Username: Password: Remember me

TOPIC:

Z2 750 crank (Bossie the Kaw) 19 Sep 2015 04:59 #690805

  • SWest
  • SWest's Avatar Topic Author
  • Offline
  • Moderator
  • Moderator
  • Posts: 19811
  • Thank you received: 1980

Tyrell Corp wrote: What's the deck height on that :laugh: Some of these marine deisel engines are the size of a block of flats, quite amazing really.


Yeah, 1015 and 10.25/1 pistons but with the 2.5mm drop, I'll bet it's more like 9-9.5/1. Good enough for me

I think about 1 point drop in CR for every 1mm, so down about 2.5 points? 10.25 - 2.50 = 7.75

Is it 8.5: 1 standard? If your head has been skimmed at all that will get some back. If the exhaust valve timing lines are just a bit higher than the gasket face it is one indication that the head has been skimmed.

About 3% power for every point of CR, so I guess you are down less than 10 percent. They do run nice and smooth though you have noticed.




Attachment Compression_Power.gif not found





www.daytona-sensors.com/tech_tuning.html


Looking at your chart makes me want to get a 903 crank. On the other hand, I shouldn't have any problems running regular gas. :whistle:
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

Please Log in or Create an account to join the conversation.

Z2 750 crank (Bossie the Kaw) 19 Sep 2015 06:03 #690815

  • SWest
  • SWest's Avatar Topic Author
  • Offline
  • Moderator
  • Moderator
  • Posts: 19811
  • Thank you received: 1980
I guess it's time to close this one out. If anyone has some info on the Z2 750 crank, rod markings, numbers on the crank throws etc. Please post them here. I am confident it is a 750 crank but little is available on identifying markings. I started the Poser thread in response to one members questioning my truthfulness. Rather than stoop down to his level, I did my best to prove what I claimed is true.
In the end, I satisfied the question if nothing more than to myself.
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

Please Log in or Create an account to join the conversation.

Z2 750 crank (Bossie the Kaw) 19 Sep 2015 06:06 #690816

  • z1kzonly
  • z1kzonly's Avatar
  • Offline
  • Member
  • Member
  • Sustaining Member
  • Posts: 2484
  • Thank you received: 307

swest wrote:

missionkz wrote: Steve and a few of his buddies trying to decide if this is the crank he's been looking for to eliminate any question about the 750 crank possibly
installed previously...




:woohoo: Now that's a crank. :lol:
Steve

I went out to the Bar at Lunch and burned a fatty :woohoo:
Livin in "CheektaVegas, NY
Still have a Kaw! 76 KZ900 Pro-Street.
Went thru 25 of these in 40 yrs.

And The Old Girl, Harley 75 FLH Electra Glide,
Old faithful! Points ign. Bendix Orig. carb.
Starts everytime!

Attachments:

Please Log in or Create an account to join the conversation.

Z2 750 crank (Bossie the Kaw) 19 Sep 2015 06:10 #690820

  • SWest
  • SWest's Avatar Topic Author
  • Offline
  • Moderator
  • Moderator
  • Posts: 19811
  • Thank you received: 1980
That stuff makes me stupid. I don't do it anymore. :lol:
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

Please Log in or Create an account to join the conversation.

Z2 750 crank (Bossie the Kaw) 19 Sep 2015 07:31 #690834

  • SWest
  • SWest's Avatar Topic Author
  • Offline
  • Moderator
  • Moderator
  • Posts: 19811
  • Thank you received: 1980
Put the 125's back in. Much crisper. Going for a short ride to see how it does. :woohoo:
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

Please Log in or Create an account to join the conversation.

Z2 750 crank (Bossie the Kaw) 19 Sep 2015 07:59 #690838

  • Tyrell Corp
  • Tyrell Corp's Avatar
  • Offline
  • Member
  • Member
  • "You were made as well as we could make you"
  • Posts: 1688
  • Thank you received: 263
A comp test at 500 and at thousand miles will tell you the real numbers. Mines at 165 last check so thinking its right at 10/1 or a hair under.

But remember CR and compression pressure is not exactly the same thing, the wilder GPz variants often have lower compression pressures despite higher CR due to the hotter cams.

What are the chances of that being a pre z1 750 crank?

Assuming the extra squish doesn't cause problems, you have a great candidate for a turbo bike with the modest CR and mild cams. And with all that clearance you can rag the nuts off it without piton/valve interference.

Don't close the thread, I think it is interesting. These jobs always take a long time of planning and accumulating parts beforehand, so nice to see it coming together and up and running with a few days. ;)
1980 Gpz550 D1, 1981 GPz550 D1. 1982 GPz750R1. 1983 z1000R R2. all four aces
The following user(s) said Thank You: SWest

Please Log in or Create an account to join the conversation.

Z2 750 crank (Bossie the Kaw) 19 Sep 2015 09:49 #690850

  • SWest
  • SWest's Avatar Topic Author
  • Offline
  • Moderator
  • Moderator
  • Posts: 19811
  • Thank you received: 1980
Put about 50 miles on it. Sky valley, to 1000 Palms, to Desert Hot Springs and back to Sky Valley. Running about 10* hotter. A little blubbery just off idle. Pulls clean up to 6000 RPM. Good strong throttle response off the line and in fifth gear. A .5 step up on the pilots is a big jump. Over 100 now so I'll check the plugs in the evening.
Maybe I should put the 60's back in and raise the needles?
It came out of a wrecked Z2 750 engine. I don't plan on putting a Turbo on it, I don't want to be launched off a cliff. :lol:
I'm thinking on sending this thread to the original Poser thread. Lots of info there and combining the two just makes sense to me.
Comments?
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

Please Log in or Create an account to join the conversation.

Z2 750 crank (Bossie the Kaw) 19 Sep 2015 11:51 #690867

  • KZB2 650
  • KZB2 650's Avatar
  • Offline
  • Member
  • Member
  • Posts: 1442
  • Thank you received: 253

Tyrell Corp wrote: A comp test at 500 and at thousand miles will tell you the real numbers. Mines at 165 last check so thinking its right at 10/1 or a hair under.

But remember CR and compression pressure is not exactly the same thing, the wilder GPz variants often have lower compression pressures despite higher CR due to the hotter cams.

What are the chances of that being a pre z1 750 crank?

Assuming the extra squish doesn't cause problems, you have a great candidate for a turbo bike with the modest CR and mild cams. And with all that clearance you can rag the nuts off it without piton/valve interference.

Don't close the thread, I think it is interesting. These jobs always take a long time of planning and accumulating parts beforehand, so nice to see it coming together and up and running with a few days. ;)


Thanks Tyrell so your saying since I put in the slightly warmer 750 cams I am a "little" bit better off yet ? Maybe I'll get to that 101/4 to one after all. :) Only went with a min cut on the head APE said .004 got it and it looked perfect. Moving this to the original Poser thread sounds good to me.......I'm interested in following your build Steve.
1978 KZ650 b-2
700cc Wiseco kit 10 to 1.
1980 KZ750 cam, ape springs, stock clutch/ Barnett springs.
Vance and Hines Header w/ comp baffle and Ape pods, Dyna S and green coils, copper wires.
29MM smooth bores W/ 17.5 pilots, 0-6s and 117.5 main
16/42 gearing X ring chain and alum rear JT sprocket....
The following user(s) said Thank You: SWest

Please Log in or Create an account to join the conversation.

Z2 750 crank (Bossie the Kaw) 19 Sep 2015 12:17 #690872

  • Tyrell Corp
  • Tyrell Corp's Avatar
  • Offline
  • Member
  • Member
  • "You were made as well as we could make you"
  • Posts: 1688
  • Thank you received: 263
KZB2, your head skim really is very minimal, a 'gnats willy' is the technical term i think. Your CR increase will be quite minimal on that, as a guess less than 0.25 points.

More duration and overlap onthe cams increases power and brings it up on the rpm range...think grunty z650 compared to screaming redline zx750 unitrack. A very nice compromise might be GPz750R1 cams, if you can find.

What i like about this thread is it is 'wrong' , just like my earlier'wrong' low compression GPz 550 build that worked really nice -until I trashed a piston 5k miles later. All the muppets laughing at Steve as he has a part he hasn't correctly identified - join the club, this is what happens when you hoard 30 year old motorcycle parts.
1980 Gpz550 D1, 1981 GPz550 D1. 1982 GPz750R1. 1983 z1000R R2. all four aces

Please Log in or Create an account to join the conversation.

Z2 750 crank (Bossie the Kaw) 19 Sep 2015 13:17 #690882

  • SWest
  • SWest's Avatar Topic Author
  • Offline
  • Moderator
  • Moderator
  • Posts: 19811
  • Thank you received: 1980
It was also said, "I haven't heard of this as being done before. Was it a combination of slightly shorter rods, wrist pin location and piston crown? I'd like to know. 12mm is a lot. I think I've accounted for 2.5mm, where did the other 9.5 go? :unsure:
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

Please Log in or Create an account to join the conversation.

Z2 750 crank (Bossie the Kaw) 19 Sep 2015 14:12 #690895

  • missionkz
  • missionkz's Avatar
  • Offline
  • Sustaining Member
  • Sustaining Member
  • Posts: 1662
  • Thank you received: 186
Is the 750 stroke the same but the 750 rods are shorter? Or is the pin boss lower in the skirt on the 750? I have no idea.
Bruce
1977 KZ1000A1
2016 Triumph T120 Bonneville
Far North East Metro Denver Colorado

Please Log in or Create an account to join the conversation.

Z2 750 crank (Bossie the Kaw) 19 Sep 2015 14:44 #690896

  • SWest
  • SWest's Avatar Topic Author
  • Offline
  • Moderator
  • Moderator
  • Posts: 19811
  • Thank you received: 1980
I've compared the pistons. What I didn't have were the stock 8.5/1 pistons to match against. Now I do. The stroke is supposed to be 58mm. The 903/1000 is 66mm. Even if the rods were 2.5mm shorter, the wrist pins are lower and the piston dome is 10mm. It still doesn't add up. Or does it? I used the 750 sleeves in my 903 barrels. Mine were bored off center buy a clown that had wrecking yard/.shop. I took them to Clupper racing and had them bore them out. He complained they were so thick and were spinning in the block he almost gave up. Would the block have something to do with it? :unsure:
Bruce, when you went to your 1075 kit, were your 1015 pistons even with the deck? If so did your 10.5 pistons sit above the deck?
This is one of those things that will bother me until it's solved. :pinch:
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

Please Log in or Create an account to join the conversation.

Powered by Kunena Forum