KZ 1000 piston to clyinder wall specs?

Got another request? I can't find a manual in the search for a 78-80 KZ1000 - 1015cc engine.
I would like to see the service limits and specs. for the stock engine.
Here is the 903cc factory manual page. I would love to see the 1000cc page like this picture
I have a nice low mile (14,400) set of pistons that I am cleaning up.
A quick caliper check gives me 2.753" at the skirt bottoms on all 4 . The other micrometers and bore gauge are at another machine shop with the race car.
I only get there about once a week. 60 mile round trip.
Thanks.

0.043 - 0.070 mm is the "Standard" for Piston/Cylinder Clearance. There is no "service limit" listed though.

The Piston Diameter is listed as 69.942 - 69.957 mm, with a Service Limit of 69.80 mm. This should be measured 5mm from the end of the skirt.

The Cylinder Inside Diameter Standard = 70.000 - 70.012 mm with a Service Limit of 70.10 mm.

If we do some math and take the 70.10 mm - 69.80 mm = 0.30 mm which is a ridiculous amount of clearance.

When redoing my KZ750 I measured everything very carefully and was surprised to find a fair bit of clearance even though the engine had only done 11k miles since new. The worst cylinder was at something like (going off memory) 0.0038" clearance. The out of round and taper was just inside .001" so I decide to just rering and run it. I used a 320 grit bottle brush hone and new OEM rings.

At any rate, my opinion is that as long as the clearance is within .0045" or so and the taper and out of round is .001" or less then I'd just run the engine (with new rings).

I own that manual. The pages are well worn. If you need any specs or procedures just pm me and I will be happy to share.

I give up trying to post pictures.... here.
No matter how I save it or how I rotate them they ALWAYS are F'n sideways or upside down or some other BS

One more time at this is it.....
By the way, 69.926 mm is your measurement.
Inches divided by .03937 is very very close to the number in millimeters.

Thanks All! Just what I was looking for. Theses should make some nice items when cleaned up.
Mark II engine with 14,000 miles. quick piston # 2.754" / 69.96mm.
Marty
By the way Ed, The Congrts. on the 750 BOTM Nice Job!

missionkz wrote: I give up trying to post pictures.... here.
No matter how I save it or how I rotate them they ALWAYS are F'n sideways or upside down or some other BS

Bruce, you can e-mail them to me and I can send them back corrected if you'd like.
Steve

If you can get your hands on a decent quality bore gauge checking out of round and taper in the bores is a good idea. Standard rule of thumb is no more than .001" for each. If the bores are worse than this the ring seal will suffer.

Nessism wrote: If you can get your hands on a decent quality bore gauge checking out of round and taper in the bores is a good idea. Standard rule of thumb is no more than .001" for each. If the bores are worse than this the ring seal will suffer.

Right. Nothing exercises the bejesus out of piston rings like a way out of spec cylinder taper in the bore.... they will eventually just stop putting any real sealing pressure in the cylinders.
I think that is worse then a slightly large piston to bore clearance... I've run engines for many thousands of miles with very large piston ring end gaps and skirt to bore dims of +.004".
Good rings still seem to hang on when the engine gets warmed up.
A backyard mechanic rule of thumb for piston clearances is about .0015" clearance for every 1 inch of bore is usually OK.
However watch out for cam ground pistons as they are not perfectly round and you'll find big gaps and small gaps with respect to the piston wrist pin area and 90° away.

Yes! cylinder boring is an art! with taper? My Guy over the years "Jim's Cylinder Heads" knew 4 cyl. Jap engines
Jim ran Top Fuel Kawasaki Nitro 80's -90's with Elmer, Larry, Sands, Hand, etc.
There was an art to this with temp. changes and expansion. I know all of this stuff! Boring plates, cold packs. Old news to me.
But, going back to stock was never my thing! I always went bigger and better!
I will measure this stuff out. I'll post some pics. I have a ball stone 320 grit for scuffing the stock bore.
I always do work as if I was going to use the stuff myself! To my standards! 40 years experience!. But I never did the stock stuff OEM! (LOL)
It always was modified. So going back to stock OEM, is like learning over!
But thanks for all the input! I'll keep my phone camera around when I work on this stuff to show some progress.
Here are some old photo's of stuff I worked and sold on ebay!