.025 rings in std bore

[haroldpo6]

I have a 84 125m that needs rings but i can't find any std size rings to fit it. However i have a .025 piston .025 rings. Can i use them if i file the end gap to correct size? I don't want to have the cycle bored to use the new piston if i don't have to. Around here they charge $75 just to bore it.

[haroldpo6]

I have a 84 125m that needs rings but i can't find any std size rings to fit it. However i have a .025 piston .025 rings. Can i use them if i file the end gap to correct size? I don't want to have the cycle bored to use the new piston if i don't have to. Around here they charge $75 just to bore it.
Thats .25 not .025mm

[shortline10]

75.00 to over bore is well spent in my opinion but to answer your question yes the rings can be filed to fit , make sure you at least hone the cylinder .

[haroldpo6]

They use to be 2 machine shops here and either one would do it for $30, one closed/retired, soooo the one left went thru the roof on prices, greed. Alot of people drive 50 miles to another shop to have there work done because of this.

[shortline10]

I wish it was only 75.00 in my area .

[ATC200X4716]

I would suggest boring it. The clearance with the old piston will never be right, and it does need a hone at least so the rings seat, but it will probably use oil. How does the surface of the cylinder look? Find a reputable shop as some just open it up a bunch to get the piston to fit. it was so bad in my area, that 20 years ago I bought a sunnen hone to do the cylinders properly. I bought supposed kits ready to go and the piston clearance was double what it should be, which is a waste of time. If you were in CT I would say bring it over and bring a case of beer and we'll bore it....

[haroldpo6]

The cylinder bore is stock and looks great and the old piston fits good also. I just could not find any std rings, so i went with .25mm ones.

[Rick1956]

I just got back from picking up a cylinder bore... $137.

A huge amount of shops are gone. Maybe COVID-related, maybe not. I think it reflects the culture shift of people being less interested in the car itself than the creature comforts it's equipped with.

[207wheelin]

Getting hard to find a shop that does good work near me. Hav ed you guys ever shipped one to G&H for boring? I have brought parts to shops near me and the results were not what I expected at all. I had parts damaged beyond repair and parts that were way out of spec. It's a shame. Nobody cares about the quality of their work anymore.
Take care
207

[haroldpo6]

Got all the rings filed and
cylinder deglazed and head installed

[haroldpo6]

OK guys i need some help setting the timing on the 125m after installing new rings. I looked on u tube for a video but found none for a atc125m or trx125. I've build quit a few ct70 and z50 engines but not a 125 w/ CDI Thanks Harold

[haroldpo6]

I found a atc110 video should work.

[ATC200X4716]

If anyone gets stuck and needs a cylinder bored or honed, shoot me an IM. I do them for $45 a hole plus return shipping. I can hold them usually within +/- .0001 which most shops can't even do. Don't be fooled by a cylinder that looks good. I've seen plenty of people run a stock piston in a .25mm overbored cylinder and it looked fine until you wobble the piston. In a properly sized cylinder the piston usually will not rock at all.

[haroldpo6]

Stock bore w/ stock piston +.025mm rings filed to fit.

[DAM shop]

If anyone gets stuck and needs a cylinder bored or honed, shoot me an IM. I do them for $45 a hole plus return shipping. I can hold them usually within +/- .0001 which most shops can't even do. Don't be fooled by a cylinder that looks good. I've seen plenty of people run a stock piston in a .25mm overbored cylinder and it looked fine until you wobble the piston. In a properly sized cylinder the piston usually will not rock at all.
Same price if you are going big bore or is that 45 for a standard 1/4-1/2 over bore?

[ATC200X4716]

If it's big bore in the existing sleeve maybe $50 just due to the extra material removal having to set it up on the mill to bore it first, but then the honing is easy cause it's just a few thousandths. For anything .25 or .5mm over I just hone them to size because by the time I get them straight I'm already half way there. I hone them to size, and then finish them the following day because as they cool the actually close up measurably. I like to have the piston to check the fit, but will fit them to a number if you are using a Wiseco as those are the only ones i have seen that are spot on diameter. I can't do anything with Nikasil I don't have diamond tooling.