Need Piston bore sizes of Robin Eng. ; EX17

Question edited for clarity.

AI Chat GPT4 answer by Shwet Kashyap deleted.

When the vehicle standard size rings are used and this will be mentioned in the Service Manual. If the cylinders are rebored, oversize rings are used and there is normally 2 larger sizes. If you are replacing rings, you should always use an internal micrometer to measure the bores because the bores can wear oval across the bore. This is caused by the lateral force of the connecting rods. If the bore is within limits they should be honed. This removes the glaze and makes the bore slightly rough so that the new rings and bore polish themselves together to make a good fit.

Pistons, piston rings, circlips and gudgeon pins in this link.

https://www.google.com/search?q=1999+Daewoo+Lanos+1.4+piston+rings

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When you remove the cylinder, you should have the bore checked by a machine shop. The bore wears on the front and rear of the bore and can wear slightly oval. In which case it should be rebored and an oversize piston and rings used. The cylinder should also be honed so that the new rings and the bore wear in together and make a good seal. The standard is 56mm.

https://www.google.com/search?q=2004+DT125re.+What+are+piston+and+ring+sizes

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Whenever a motor is taken apart so that you can install piston rings, it is rather common to replace many other parts at that time.
Commonly, all of the replaceable bearings ( crank & cam) are changed.
Also commonly, the engine block is bored so that new pistons can be fitted, because of wear on the cylinder walls.
Commonly, an inside micrometer will tell the technician how much to bore the block.
The block is usually bored from .010 up to .040.
If the block is so bad that a .040 will not be big enough, the block is scrapped out.
Then, "oversized" pistons and rings are fitted to the new size hole.
You would measure the size of the bore to tell which size rings to buy.
God bless your efforts.

No, You need to get the specs on that bike,and see what the standard bore is on it. It may be that your standard bore is 45,and the cylinder needs to be bored out to accept a new oversize piston.

ASE SX 2200 6.0 hp Robin EH17, EX17 NGK SPARK PLUG

The bore has to be measured at a number of places to see if it is out of round 0.01mm or tapered 0.05mm
You will need to take it to an engineering shop that can do the boring, they can measure the piston and bore to determine what oversize it will need.
with only light scratches probably 1 oversize 0.25mm, if it has been bored before the oversize is stamped on the top of the piston. 0.25, 0.50, 0.75
A rough measurement can be done with a feeler gauge, between the piston skirt and bore.
piston clearance for a 125 is about 0.055-0.060mm with a limit of 0.1mm

well, there is no surgery i know of to fix your problem. you could hang a brick off a string tied to it for awhile,but that will just make it long and skinny.what i am thinking is a combo vacuum chamber with a suspended wieght on it. hell, it might work! but the most common cause of your problem is that the "piston" is to small for the "bore" big blocks are not your cup of tea. i suggest mabee a old 265 chevy or 260 ford.if still no fit well then briggs and stratton/teachumsa/wisconsin might be the right direction, or perhaps a fine japaneses model such as robin/honda/suburu, also dont forget china, they have many small bore engine blocks.

It depends on how deep the gouge is. Having it bored and a new oversized piston may set you back more than a new stock piston and cylinder.

The cylinder bore is just that > the bore size of the cylinder. The piston clearance should be 0.0015 to 0.003. Anything more than .005 and the piston is too loose.

First, be sure they actually do fit the bore. Take a ring and insert it in the bore. push the ring halfway into the bore using the piston. There should be about a 1/32" gap in the ring. Anything more than 1/16" and you need rings the next size up. If the ring won't go into the cylinder because the gap fully closes, the rings need to be a smaller size.

With the correct size rings, put them on the piston. Some pistons have an index pin in the ring groove Fit the gap to the pin. Put the piston mid-stroke and place the cylinder over the top of the piston. Squeeze the rings closed as you gently tap the cylinder downward and over the rings.

Please rate this solution. Thanks garethholleb!