Trying to figure out if cases have been ground

More on this lot of machines I bought.

Anyone know the standard bore of the 900s/1000s?

The fours sets of Z1/KZ900 cases I measured were ~76mm to 78mm front to back. Guessing stock?

I've got a set of 1000 cases and the bores in upper case look effing huge, ~89mm front to back. :ohmy:

The PO was heavy into drag racing, so anything is possible.

Got 3 sets of cylinder blocks that are standard - 66mm, and one that is 74mm (KZ1000 block). Also have 3 pistons that came with everything - 80mm - big suckers.

Thanks

What brand of pistons are the three 80mms you have. How about the compression.

The machining in the cases from the factory usually look like it has been painted. Aftermarket bore job looks like raw machined aluminum

No markings on the pistons. Crowns look shallow to me. No even sure they are z/kz.

APE Jay wrote: The machining in the cases from the factory usually look like it has been painted. Aftermarket bore job looks like raw machined aluminum

The 900s cases all look like they have paint, the ports are not pefectly round, and have a slope to the side of the wall of the opening - assuming stock.

The KZ1000 head on the other hand, have big round holes with what looks like maching marks.

Pics below..

RobK wrote: No markings on the pistons. Crowns look shallow to me. No even sure they are z/kz.

Attachment 2013-05-1212.45.29.jpg not found

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They look like early MTC pistons.

you should always measure pistons on the skirt 90 degrees from the wrist pin,because they are oval and tapered and the skirt is the largest area.





those cases you showed have been bored out for sure.

leon

531blackbanshee wrote: you should always measure pistons on the skirt 90 degrees from the wrist pin,because they are oval and tapered and the skirt is the largest area.

those cases you showed have been bored out for sure.

leon

Thanks very much - good to know! I'm guessing that case was bored out for a pretty meaty increase in displacement as I know you can go up significantly without touching the cases.

That makes me think I'm gonna sell those as I understand that going that far up (with an air-cooled engine), means a much higher maintenance motor, (eg. not a daily rider).

Those cases are bored. We may have done them. Is there a number engrasved on the bottom of the motor mount area?

Those pistons are old MTCs.

APE Jay wrote: Those cases are bored. We may have done them. Is there a number engrasved on the bottom of the motor mount area?

Those pistons are old MTCs.

Thanks.

Couldn't find any numbers engraved except the SN, oil capacity, and case bolt numbers. These cases have been in a garage for at least 13 years. Have you always marked your cases?