Z2 750 crank (Bossie the Kaw)

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...

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

Yikes, that is 5/16".....

Now that's about as low in the cylinder the stock 1015 pistons are. Not 8mm.
Steve

hows that z2 crank doing in your 892 cc motor?

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.

Two foregoing posts moved from Carburetor forum.

Good Fortune!

No eBay APP ID and/or Cert ID defined in Kunena configurationWon'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

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.

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

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

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