Wrong size piston rings for my T500?

[Stan]

I am working on my '72 T500 and pulled the cylinders. I thus thought it wold be worthwhile to put in new rings. I ordered 'standard size rings', but have had no luck getting the pistons back into the cylinders. This morning, I pulled the rings off the pistons and took a close look: the rings are marked for left and right, but also have a "5 O" mark. Does this mean that these are .5MM oversize rings? If so, that would explain a great deal!

Any help or insight would be appreciated. Thanks.

STAN

[Pete O'Dell]

never seen rings marked left and right as it makes no difference, the size markings would "usually" be .05

firstly as I dont know your history or ability lets as simple questions, have you lined rings up with pegs and are the rings up the correct way ie markings upper most, if not they won't fit in the piston properly as they are tapered

[Stan]

Thanks for the response, Pete.

I understand your need to learn my level of awareness. Yes, I did align the rings with the pegs and was certain to have the rings right side up. I have done rebuilds of this sort a few times over the years, most recently with a Honda CX500. This is the first time I cannot get the piston back into the cylinder. That's why I wonder if its the wrong size ring.

I did not bore out the cylinders, so I need standard size rings. Again, I wonder if that "5 O" mark on the rings means they are oversize by .5mm. Of course, I no longer have the old rings, so I cannot compare them.

Again, thanks for your help thus far.

STAN

[Zunspec4]

Hi Stan,

The way to check if your new rings are the correct/in-correct size is to insert them in the cylinder bore (not fitted to the piston obviously) and measure the gap between the ends. You will need to check with the workshop manual what the gap should be, although if they are + 0.5 oversize it would be pretty evident.

Cheers Geoff

[Stan]

Great idea! Thank you, Geoff!

I did as instructed and found that the ring overlapped itself!! It is painfully clear now that these rings are too big. I think I will contact Paul Miller and order some new standard size rings.

Any other piston ring issue I need to watch for?

Once again, thanks for the counsel.

Stan

[Pete O'Dell]

beat me too it Geoff