To Bore or not to Bore? GPZ550

I have a 1982 GPZ 550 that was given to me. PO (my brother) ran it lean with pod filters and an exhaust leak, and blew a hole in one of the pistons. I thought the cylinders were in pretty good shape, but when I looked closer, I noticed some scoring in 2 of the cylinders. One pistons rings were seized, and that cylinder is scored the worst.

I'm a noob, and have never bored an engine. What do you guys think, judging by the pics? Is it necessary to bore it?

Also, the Wiseco kit seems to be the most popular choice from what i've read on this forum. The only problem is i'm on a very tight budget with this thing. I've crunched the numbers and Wiseco kit, boring, and gaskets will probably cost me $600-$650. Seems like a lot of money for a bike that still needs a lot more TLC after I button the engine up. I'm tempted to try one of the cheap big bore kits on Ebay...$140 shipped, Does anyone have any experience with these "no-name" generic kits? I'm skeptical, but the price difference makes it very tempting to at least try. If it's shite, well, lesson learned and i'll save up for the Wiseco. Any help would be appreciated.

Austin

If you google 'criuzin image' pistons, or Forsetti here recently here there are conflicting opinions, but not much in the way of facts. For a standard motor in mild tune then I think they would be ok. They ship from japan but are chinese manufacture.

Do the fingernail test on that one bore. If it sticks you may have to bore one and get a oversize piston and rings. Looking at the valve pockets it looks like those are 9/1 pistons. Be careful about buying no name pistons. You may get lower compression ones.
Steve

I googled and found quite a bit of positive info about those Cruzin Image kits. Most negatives were from guys that didn't use the kit.

Yeah i'm not planning to tune this thing for high performance or anything. Just something to commute on and whip around town. If I do go with the cheap kit, i'll post pics and do a "review" of sorts.

I'll do some more googling. Thanks Tyrell.

Swest - Definitely feel it with my finger nail. Looks like I'll be boring. Good call on the compression...hadn't really thought of that. The bike has 9900 miles, so i'm thinking they're the OEM pistons? I'll have to check the stock compression specs for my bike,

Nessism - Good info, thanks. I'm leaning towards the cheapo kit at this point. As long as they're the right compression...

Thanks guys

I was looking at them. Some aren't standard bores. As long as they are, you can slip in some high compression Wisecoe's later.
Steve

It is impossible to suggest anything looking at your pictures. Here is why:
Is it aluminum from pistons or deep scratches left by broken rings?
If this is aluminum, use razor blade to remove it.
If this is scratches, I need to know how deep they are.
To evaluate pistons you need to check them with a measuring caliper, they can still be reusable, except piston with hole, of course.

True but I wouldn't use the ones with the scratches in them. The last thing you need is to have one grenade on you.
Steve

The bores are done. At least one of the pistons seized in the bore. There is no going back from there.

You may be able to find a low mileage stock cylinder, but ebay seems kind of dry in that regard.

If you are in a tight budget then go for the Cruzin Image piston kit. Search the web for reviews, kits for kawasaki are new, the have only been around for a year. But piston kits for other brands like Honda, Yamaha and Suzuki have been around for more than five years and have great reviews in specialized forums.
Remember they are cast piston, not forged.

If the damage is limited to 1 cylinder, the individual sleeves can be replaced. I haven't checks specifically for the 550, but they're around $60 for the 900/1000. The sleeve will need to be bored to stock piston size and the block decked. You'll be in about $200 for the sleeve/machine work. Having all 4 cylinders over bored might be in a similar price range. You'll still need to find a single stock piston. Aftermarket pistons are typically sold as a set. Buying a single OEM piston may be more expensive then the complete aftermarket set. You'll have to do the math. This all assumes that the other 3 cylinders are good. If you're considering the single sleeve route, the FSM gives all the cylinder measurement specs. Copy those pages and take it to an automotive machine shop for measurement of the other 3 cylinders. The small cost may save you a lot in the long run.