Z1OwnersClub GB

A per the title, can you mix top and bottom engine casings on the same generation of engine ?
I have some damage on the lower casing but the top is fine.

Anyone got a casing for a z1000A1 they might want to part with ?

Not really, they are a matched pair and machined together to get perfect tolerances, though i have heard of cases being mixed but i wouldn't risk it, there are risks of the bearings being off a fraction, causing vibration and fracture, it would be a safer bet to find a new set. Sorry for your troubled mate, what number range were you in?

Cases are lined bored as a pair so not really recommended although it has been done and not unheard of in racing circles back in the day but those motors won't have been run for extended periods between strip and inspections.
I have had some that were a mismatch and they showed evidence of the outer main bearings vibrating in their seats due to less than snug fit.
What sort of damage is on your lower case as virtually anything is repairable.

Current engine number is KZTAE-018387.

I'll try and get some pictures of the damage but it's right next to where the oil pump outlet mates to the casing. It looks like someone has potentially but too long a bolt in the engine-frame mount that is right next to it. There is a plug there that banks off the channel to the oil filter and it's in the casing wall there.
TBH I'd be worried about a repair too unless it was done by someone who really knew their sh1t. I've got an AC/DC tig but I wouldn't really attempt it

Seen it before on a few cases if it's a crack in the ally around the steel bung and not up the casting to the pump 'O' ring seat.
Usually isn't a problem unless it has an oil leak which is more than a weep affecting the feed pressure to the main gallery etc.

I'm not happy putting it back together like that. What do others think?

Not a hard fix if you can Ali weld. Just need to find someone who can Ali weld.

Yes! Exactly as i've seen and had many times to varying degrees and from what i can tell it's very likely they have all been like that from when they pressed the tight fitting steel bung in at the factory and that popped casting isn't going to get any worse after all these years.
If the steel bung isn't loose and leaking you can either leave as is or you could simply dress the high spots and sweat in some low temp ally solder like Lumiweld or similar if you don't want to tig it which i don't think either is really needed.

thanks zed1015. I may just clean it and dress back a bit to see how stable it is then.
I might even have a gentle go at it with the TIG.

Yes! it's not structural.
You could actually section out the fractured pieces as long as either end of the drilling remains plugged so no oil can leak out of the engine mount or short circuit direct back to the sump from the pressurised pump side but i wouldn't.
On my Drouin build i had a loose steel plug which leaked oil from the engine mount side and had to machine up and fit slightly larger one.
It also had the same popped casting which showed signs of oil leakage back to the sump that i just peened shut although it didn't really need it once the new plug was in.

I've ordered some Lumiweld. It does not appear to be leaking so I'll just aim to make it stable. I'll be more comfortable hitting it with heat from a gas torch than the TIG so I think it will do the job from what you've said.
I'll let you know.

When fitting the top and bottom casings together is there a joint sealer required ? I see no evidence of it on mine currently. If so, any recommendations ?

Yes! You need sealer on the cases.
I use this Vtech .
https://www.ebay.co.uk/itm/283503832697?