hi ruckusman! here it is, straight from the service manual, tanks for getting involved! @Murdo don’t want to modify the pistons really ... my rings are thicker than what’s out there, 1.175-1.190 mm
the thing with these rings is they are thicker than the other ones i found, not sure what thickness are the honda cb/ca125 i messaged several people selling them if they don't mind measuring that for me. i also bought 4 sets of 2 stroke 49cc 44mm rings because they were preety cheap and from the pictures they might be what i need, not sure of the materials they're made off etc we'll see.
I don't think the two stroke rings will work because they have a locating pin in the pistons to prevent the rings from rotating, so the rings themselves will have scallops out or their ends to accommodate that locating pin
Regarding rings that are too thick but otherwise the correct size, you can get them ground down. A surface grinder with magnetic chuck will do the job. How about these https://www.aliexpress.com/item/400...earchweb0_0,searchweb201602_,searchweb201603_
I asked around on ebay for people to measure the thicknesses and i got one life changing reply. I finally found out that the Honda CB125T does the same , fingers crossed, piston rings, 44mm bore 1.2mm thickness so I went ahead and ordered 2 sets as the Honda only has 2 pistons. It's from the same era, even the piston thickness is the same , slimmer in the ring area. My piston groove is 1.21-1.23 and the original piston rings are 1.175-1.190 but by this time i'm willing to buy a lathe and modify the piston groves if i need to although i hope 1.2 was not a precise measurement by the ebay seller I'd rather do that than spend £420 on 3 sets of pistons.. i did see a clip on youtube with a guy making piston rings using a lathe... i'm future proofing myself here. Wish me luck, they were considerably cheaper than £420 for 3 sets of just the pressure rings (only the first 2) from a company called Cox Turner Engineering and was desperate enough to almost accept it. piston-rings I'm linking them here in case anyone is in the same situation.
I've still got 3 pistons and the cilinder from my previous engine, i'll try them on one of those first.
ok a bunch of good news ! 1) the rings came and they fit!!!!! 2) i did a leakdown test , despite that my tested was a bit leaky before connecting the cylinder hose for some reason... but quickly found a way to work around that, and the results are: Tatananatatatataaaaaa!!
this concludes that my initial pressure tester is ****.... and i actually did a pressure test one more time and felt the hose to the manometer expanding on the compression stroke...., found this guy on youtube with the same problem and tester as me... i further investigated this tester and directly linked it to my compressor and pushed 6 bar into it, the gauge was showing 5.6 bar but at constant pressure so at constant pressure it is somewhat accurate... the 3rd bit of good news is that now that i’ve ordered a set of rings and a new engine gasket set i future proofed myself for the next refurb! in conclusion don’t buy that compression tester ever! luckily i did another test before attempting to dismantle the engine again for no reason))
So you fitted the new rings? I cannot see anything in those images except a needle in the green for leakdown.
didn’t fit the rings to the engine, i don’t have to, nothing’s wrong with my engine, it was that cheap compression tester that was waaaay inaccurate. the leakdown test went really good for all four cylinder , that means i’ve got proper compression . as for the fitting of the rings , i tested them on a loose piston i had from my previous engine and they slide in the groove just fine