My piston blew so I am upgrading! Kz1000 to 1100

So my number one cylinder blew up in my Kz1000 J motor (1981 kz1000m csr)
so I was hoping I could hone the cylinder but alas no. So a buddy on here approached me about:
gpz1100 jug with piston , rings, and wrist pins.

He let me know that I can just go to this jug and pistons and upgrade the bike to an 1100 without any issues, or mods.

It makes sense but I wanted to post to see if anyone here has done this and if so, what problems if any did you run into.

Thanks in advance.

Your question in the other thread:

So I currently have a kz1000j motor.
Want to swap a bad jug for a 84 gpz1100 jug with pistons
is that doable?

And my answer there:

No, not directly, the 83/84 GPz 1100s use 18 mm wrist pins, the 1000J (and 81/82 GPz 1100) use 17 mm.

81/82 GPz 1100 jugs and pistons will fit the 1000J bottom, but you will need an extender head gasket - the GPz's have shorter con rods and the wrist pins sit lower in the pistons, you'll have to make up for that if swapping.

how would I look up that gasket?

I'm sorry, memory failed me so I have misinformed you about the conrods :blush: Also, it's not a gasket, but a spacer plate under the block. :pinch:

Both GPz and J models have shorter con rods than the early 1000's and the wrist pins sit lower in the pistons on both - you'll only need a spacer if you use J or GPz pistons in an early style (long con rod) engine. Sorry for the confusion.

The 83/84 GPzs do use 18 mm wrist pins though.

www.aperaceparts.com/tech/techkz1000.html

what about the head can I use my kz100 j head on the gpz jug?

so close. but so far. So this the info I have gathered so far:
Reference:
Bike 1981 kz1000m CSR, Engine is the kz1000j

jug, pistons, and rings are from a gpz 1100 1984

I want to use the crankcase from the kz1000j and then the pistons, rings and jug from the GPZ1100

and the head and vavle cover from the kz1000 j

I think the whole thing is doable. Except I have gotten conflicting info about the head. Two guys are saying no the kz1000 head will not work, and one is saying it will.

anyone tip the scales for me. If I want this jug I need to jump on it. but if I make another mis step I will not be riding this season at all anymore. (my budget is tapped)
any advice much appreciated.

oh and,,,If the head does fit can I use the head gasket from a kz1000 I just bought or should I go get a gpz one?

As long as everything is "81 and later with a 17 mm wrist pin,
the only problem I see is the 1100 sleeves fitting in the 1000 block.

.

What ypu want is an 100 from an 81-83 A1/3 shaft drive or a 1100 Spectre etc. Maybe a pre 83 1100 GPZ.
Then it just bolts in, easy. Got to have the 1100 head gasket though. So sell the 1000 gasket and buy the 1100. Only the head gasket and base gasket will be bigger, so you need those two.

grrrr. some much conflicting info.

lucienmaier wrote: so close. but so far. So this the info I have gathered so far:
Reference:
Bike 1981 kz1000m CSR, Engine is the kz1000j

jug, pistons, and rings are from a gpz 1100 1984

I want to use the crankcase from the kz1000j and then the pistons, rings and jug from the GPZ1100

The problem here is the pistons - your J con rods have 17 mm holes for the wrist pins, the 84 GPz pistons have 18 mm wrist pins, just won't work together.

so If I have kz1100 pistons then I could use the gpz jug?

lucienmaier wrote: ... 1981 kz1000m CSR, Engine is the kz1000j

jug, pistons, and rings are from a gpz 1100 1984

I want to use the crankcase from the kz1000j and then the pistons, rings and jug from the GPZ1100....

The '84 GPZ1100 pistons have 18 mm wrist pins that don't fit the 17 mm connecting rods in the 81 J model's crankcase.

Good Fortune!