KZ1100 engine overhaul advice needed

Hey everyone, I'm new here, but I bought a KZ1100 as a tinkering project. I have experience mechanicing and I'm full time engineer but I don't know a ton about motorcycles.

My girl had been abused pretty bad and had a lot of wiring problems. I got those sorted out and she would just barely start with a lot of crankcase pressure and low compression in #2 and #3. I tore the engine down and the cylinders are worn out of spec .0001-.0019 OOT for the upper wear limit. So I am looking for some advice, is the right path forward new rings and don't touch the bore? Or Bore it out to 2.5mm oversized! Which is the wiseco piston? Or maybe bore the cylinder just enough to true them up and put stock pistons and new rings back in them? The other option I considered is having new sleeves made and boring back to stock diameter but that seems like alot.

I am very concerned about the 2.5mm oversized as I am in Denver and I'm afraid of burning up the air cooled engine.

I also think I am losing some compression around the valves so that will be on the list of things to fix too.

Any help/advice would be appreciated.

Thanks in advance.

Bram

Brand,

I think LA Sleeve still makes stock bore sleeves, and if you have the later J engine, they may be available from Kawasaki, too. A 2.5mm overbore should cause no overheating as long as the carburetion is properly set up.

By the way, there are basically three versions of the 1000 engine and there are some significant differences. There was the KZ version that was based on the Z1. It was used from 1975 - 1981. There was a variant of that engine called the MKII, used from 1979 - 1980 (I think). Finally the J which was used from 1981 - 2005.

Here is a basic explanation of the differences between the KZ and J versions.

www.aperaceparts.com/tech/techkz1000.html

I'd bore the stock sleeves.  LA Sleeves are awesome, but very expensive.

CruzinImage sells piston kits for cheap.  Can't blame anyone from being gun shy about them, but I've yet to hear a bad review.

Thanks TexasKZ I love getting back story about things like that, helps lend perspective. I will have to check the details but after reading that I'm certain I have a J model. 

I am getting lots of conflicting opinions about the 2.5mm oversized bores. I had one engine shop tell me they wouldn't even quote it because he had seen it burn up motors. And I have had others tell me it is no big deal. 

From what I understand more combustion volume means more fuel and air so more heat, which sorta makes sense.

I did email LA sleeve to get a quote, thanks for the idea!

Nessism,

I took a look at their website and didn't find a Kz1100 piston but I emailed them and asked if there was anything they were interested in. Thanks for the idea 

Nessism wrote:

I'd bore the stock sleeves.  LA Sleeves are awesome, but very expensive.

CruzinImage sells piston kits for cheap.  Can't blame anyone from being gun shy about them, but I've yet to hear a bad review.

I was planning to go this route (I have a GPZ1100A2 block that had one bad bore) until Warren sorted me with some 72mm Wiseco's for my 1000 block

Bram wrote:

Thanks TexasKZ I love getting back story about things like that, helps lend perspective. I will have to check the details but after reading that I'm certain I have a J model. 

I am getting lots of conflicting opinions about the 2.5mm oversized bores. I had one engine shop tell me they wouldn't even quote it because he had seen it burn up motors. And I have had others tell me it is no big deal. 

From what I understand more combustion volume means more fuel and air so more heat, which sorta makes sense.

I did email LA sleeve to get a quote, thanks for the idea!

Nessism,

I took a look at their website and didn't find a Kz1100 piston but I emailed them and asked if there was anything they were interested in. Thanks for the idea 

On "Cruzin Image" look at GPZ1100 but make sure it's the early model with 17mm wrist pins