Modify ring end profile to suit location pin.

[kdx Geoff]

Can l modify the ring ends on the top set of rings to suit the piston that the bottom set of rings came off ?

[pokey]

 Flirting with disaster there geoff.  Pistons from one company dont usually like rings from another. You have, besides the end gap style, ring profile, side clearance and back clearance to consider. Compression needs to get behind the ring to push it out to the bore to seal. thats one of the reasons you have a top on those rings(R), to let the gasses get behind the rings. Alternatively the rings could get pushed to far and roll, grabbing the bore.

[jimg1au]

can you not just change the pin my pin in my cr250 honda has been changed (location) yamaha piston in a cr250 honda
jim

[kdx Geoff]

Flirting with disaster there geoff.  Pistons from one company dont usually like rings from another. You have, besides the end gap style, ring profile, side clearance and back clearance to consider. Compression needs to get behind the ring to push it out to the bore to seal. thats one of the reasons you have a top on those rings(R), to let the gasses get behind the rings. Alternatively the rings could get pushed to far and roll, grabbing the bore.

Sorry, more info...

The bottom set are '83-'86 kdx200 and the top set are '87-88 kdx200. All the rings measure within .01 mm of each other and the profile appears identical other than the ends. The used rings are within spec but the thought crossed my mind about modifying the new rings and using them on a new piston I'm fitting.

can you not just change the pin my pin in my cr250 honda has been changed (location) yamaha piston in a cr250 honda
jim

Moving the pins is beyond my skill level 

[Lozza]

There would be a chance it could work but there would not be much holding the ring in place. RPM would be the killer. Why not find the piston that matches the ring?

[OverTheHill]

just to stir things & Lozza can correct me no worries. Back in my RM125S days i found the 'new rings' had a hell of an end gap because that year they butted straight up to the ring peg [end on]. Peg totaly filled the groove. So it was then that i realised that ring wear past the ports was the important thing for performance. So--thinking along those lines with the kdx if you have 'new' rings [& you're desperate to use 'them'] could you just file them back flat till you can get them in the bore fitted to piston & be able to move the piston [turning] left to right enough to know it's got end on clearance. Ok i'm complicating a simple question--Lozza come in. I use desperation methods here mostly but do work. Now, back to changing the water pump on my "90--5 cylinder honda vigor, shoulda taken notice of the ballancer timing marks let alone the valve timing lol.

[Mike52]

Murphy's law says that the little bit left on each end of the ring will snap off and end up somewhere it shouldn't be.

[kdx Geoff]

Thanks for the input and advice.

I won't be modifying ring ends to suit a different piston 

Cheers

Geoff

[OverTheHill]

i should've also said i've modified the ends of ring with a small file more times than i can remember over the years but most would be say using oversize rings [1st into a std bore-yamaha] so would have been following the same peg end shape on the ring. Hate to say it but have used new std rings in a first over bore to get it going for the weekend. Worked good in desperation-just not recommended!!.