Piston ring order

[yellowdog]

Can someone please tell me if this piston ring which I think is called the oil scraper ring goes in the top groove or the middle one on the piston,this ring has the little lip on it as you can just make out in the pic.I just can't remember and obviously don't want to do it wrong ,Thanks

 

[5twins]

I'm pretty sure the top two rings are slightly different thicknesses. The thinner one would, of course, fit either groove, but the thicker one will only fit the groove it's intended for.

 

[TwoManyXS1Bs]

From the 70-74 service manual:

 

[yellowdog]

So it goes in the middle then ,I was going to put it on the top ! Thanks

 

[Airwolfie]

AFAIK and remember, yeas it does. I'll have a dig in my engine build thread, the order is in there I think!! Don't forget to put the letter on the ring facing up!!!

EDIT: I didn't write the order down , I put the rings on in the order I took them off! Sorry bud!

 

[yellowdog]

Cheers ,I got the facing up bit but I think I got them mixed up when taking them off ,these are new rings from cruzin image,£16 for two sets ,we will,see what happens !

 

[Airwolfie]

As far as I can remember, the oil ring is the thicker one, i THINK! lol

 

[TwoManyXS1Bs]

Yellowdog, the MikesXS oversize piston/ring offerings for the 256 engines indicate that they use the more modern 447 rings. Perhaps they're sourced from Cruzinimage? Assuming you haven't assembled yet, could you mic your ring thicknesses, then compare those values and the ring edge profiles with post #27 in this updated thread:

http://www.xs650.com/forum/showthread.php?t=133

If these Cruzinimage 256 pistons are indeed using 447 rings, well, that would be important to know...

 

[yellowdog]

Will do ,I've just read post # 27 and it seems top and middle rings are the same thickness
1.5 mm which explains why I couldn't determine which one went where, as reading 5 twins earlier post he thought they should be different thicknesses which they are on later models,no wonder I'm confused.
I will try and measure and check the profiles as well ,Thanks.

 

[yellowdog]

Duly measured top and middle rings at 1.5mm .the top ring is Not beveled it looks like a straight edge as is the old ones that I am replacing so I don't know what to make of that .
Hard to get a good photo but have a look ,this is the new top ring .

 

[TwoManyXS1Bs]

Thanx, Yellowdog. That sure does look like a straight, non-beveled edge. And, it looks like plain cast-iron, no edge coating. Factory OEM '256' rings might just fit in there.

If so, then these Cruzinimage '256' piston/ring combos match the originals.

Which makes the MikesXS '256' pistons, with their advertised '447' rings, another/new combo to watch out for.

A lot of our period Honda rings had a practically unnoticable 1/2° to 1-1/2° edge angle on the top ring, forcing the upper part of the compression ring to wear-in/seat first. You could see this upper half wear-in pattern on used rings. That's why they had to be installed with the stamped/marked side upward.

Hopefully, your top/compression rings have this same miniscule edge angle. How's your eyeballcrometers?