Forgot to mention, burnt piston and the others are 050 -thats 50 thou bore already right?  Can it be bored again?  There is a small scratch in the cylinder that had the burnt piston.  Wondering if I do not bore it and put a new piston in-will it just happen again.

Thanks for the help folks,
Jesse

It's not really how many times you can bore the cylinders - it's more a matter of where it's at and how large a piston can you get.

Presumably we are discussing a Suzuki of some sort, or perhaps a Chevy or Geo, a rebadged Suzuki - the first oversize is generally 0.25mm, and the second 0.5mm or roughly 10 & 20 thou oversized - Suzuki doesn't sell anything larger than that.

If you were standard, you could bore twice using SGP parts - once to 1st oversize and the second time to 2nd oversize - or - you could bore once and go 2nd oversized - or if you were using third party pistons, you might be able to get pistons in 30 & 40 thou - in which case you could theoretically rebore as many as four times - or bore once to 40 thou.

You're talking about 50 thou oversized - rougly 1.25mm overbored - can you get a larger piston which will leave enough "meat" inbetween the bores? That might be a question to ask your machinist.  Is sleeving the block and boring it an option where you are (it is here) - if that's the case, you can bore it four times, then resleeve and bore another four times - rinse, lather, repeat.

50 thou oversized sounds odd - are you sure you don't mean 0.5mm?

And for what it's worth - it's so much easier to discuss an engine when we know which engine it is - what do you have - a Samurai with a 970cc engine?  a 1.3?  a 1.6?

Oh - how deep is the scratch?  Again ask your machinist - you may able to get away with just honing the bores - and the scratch is probably not the cause of the piston having a hole - it could cause some amount of blowby and oil burning though.

Sorry-
This is a 1988 JX with a stock 1.3 8 valve engine.  I dont know how to tell if it is an 1988 or 88 1/2.   Guy I got it from said it needed a weber carb-I have heard that story before on another post...Buyer Beware right.

It had spark, and was running fairly well surprisingly-just ran poorly going down the road-especially up a hill.  And it smoked more than I could live with.  Bought a compression tester to see where I was and they were all low (100-25-105-120) not exactly sure if I did it perfectly right-I was hoping to find them all about the same, but low.  The ~20 pointed me to the #2 cylinder.

Looks like someone has bored it already, pistons have 050 stamped on the top of them.  The bad one actually has a hole in it.
I know you cant tell but I tried to attach picture of burn piston and scratch-I know you cant tell how deep it is. I can feel it barely, with my thumb nail.  I would like to put it back together with new piston(s)-did not want to sleeve/bore again etc unless the new piston will rapidly burn a hole in it again.

Just trying to get this so I can drive it to work-not rock climb or race.  I really appreciate you taking time to help me.  This was definitely more involved that I thought-replace some seats, fix dents, etc. 
Thanks again for the help,
Jesse

The pictures don't open for me.

Compression tests need to be done both dry & wet to really be able to diagnose the location of your problem - I was posting the sequence to do it in, then I realised you already have the engine apart.

Those compression numbers say the engine is in poor shape - very poor shape - you want to see numbers above 170 - from personal experience those engines will run surprisingly well even when worn, I had one that was down around 90 dry and over 180 wet - started and ran smooth, no smoke and burned very little oil - it was just way down on power.

I really cannot recommend just sticking a set of pistons & rings in there - how would you even know what size pistons to get?  You need to get the bores miked to determine what size they are bored to as the first step - and at the same time let them advise you on the condition of the bores.

An 050 marking could mean 0.50mm which is what Suzuki considers second oversize (0.020") - Low Range Off Road (www.lowrangeoffroad.com) can get you 0.030" oversize if it needs to be bored - I don't have much experience with them, but that's where I got my pistons & rings from - flat topped high compression pistons in 0.020" - I've since put about 4000 miles or so on that engine, and I'm very happy with it.

fordem: thank you for your help.  There is a guy with a race car shop down the street-I need someone to look at this that knows more about this than I do.  Thanks again,
Jesse

You're welcome buddy, and it's always better if you can have someone close by take an actual "look see".

If you don't mind my sharing a little story.

Years back, when I was a young father and money was kind of tight, I pulled the engine out of my daily driver (had a friends car for a week whilst he was away), and took the block to a machine shop and had it checked - I was told it need to be bored +0.040" and when I questioned the shop, which I did because I couldn't see would should have been a standard block would need to go that large, they got very upset and told me to take it somewhere else.

I mentioned it to another friend, who also ran a race car shop and he stopped by later that day - ran a fingernail over the ridge at the top of the cylinder bore and said - you don't have 0.005" wear here - he then looked at the rings and squeezed one and said - these rings have no tension, this engine has been overheated - he picked up a piston and examined it, and showed me where there had been a partial seizure due to overheating (I had lent the car to someone else, who had experienced problems with it).

He told to put new standard rings in - and that if I couldn't get standard rings get +0.010" and file them - and that is exactly what happened - I had that engine back together & running a few days later, and ran it for many years after - the block wasn't bored, not even honed - and the cost of the repairs was a set of rings, the gasket set and my time.

This is the sort of thing that can happen - if you have someone knowledgeable to look over your shoulder and guide you