Topic: 61mm three piece oil rings

[Tretnine]

There has been a lot of talk lately in the 550 project circle about the benefits of using three piece oil rings on a 61mm overbore. Well, a lot of off handed, vague references, anyway.

For those of us new to the overbore game would one (or many) of our resident experts clear up what the difference between a one-piece oil ring and a three-piece oil ring is, what needs to be done to a piston to accept a three piece oil ring, and is there a source for these magic rings outside of full ring kits.

For example, my current project is a 550 overbore to 61mm using new (unused) yoshimura pistons. The gentleman's express article is all I know of yosh pistons and there is a fear of oil burning. What would need to be done to fit different (hopefully better) oil rings. What about henry ABE kits, other overbore kits?

[fastbroshi]

  Hey Tretnine, the stock bore 750 pistons are 61mm, they might work here.  Someone with more knowledge about them should be able to give you info wether they work or not.   Just a heads up to search with in the meantime.

[srook]

The 3 piece oil rings will fit in the earlier pistons designed for the 1 piece oil ring.  The oil ring lands are the same size on the CB750 pistons between the early 1 piece and the later 3 piece.  In fact I just installed the newer 3 piece rings on my NOS Honda .25 oversize piston kit designed for the 1 piece rings.  I don't know where to get them by themselves other than in the piston ring kits from Honda.  I don't know if the Yosh rings were different than the Honda rings.  That is going to be the question.  If they are the same troll ebay for some OEM CB750 standard size rings.  That should be cheaper than getting them from Honda.

You can see the 3 piece rings on these pistons designed for the 1 piece rings


Scott

[bwaller]

In the picture of the Yosh pistons you bought it shows four sets of rings including a three piece oil ring, are you not planning to use these?

[Tretnine]

In the picture of the Yosh pistons you bought it shows four sets of rings including a three piece oil ring, are you not planning to use these?

I will use that three piece oil if it's three pieces. Honestly, right now I'm at roughly two knowledge of a possible ten on oil rings. That being said, I don't know what a three piece looks like vs a one piece. (Sounds like a swimming suit or tux discussion all the sudden.) Using the search function I haven't been able to hammer out any details on the differences.

Just trying to put some details together for myself and anyone who uses the search function in the future.

[srook]

Here's a pic of the piston rings for the CB750.  The 3 rings on the bottom make up the 3 piece oil ring.  It is made up of 2 thin rings that sandwich the bronze colored springy ring.



Scott

[fastbroshi]

Tret I'm sorry if I led you astray, maybe I need to look at the pics better if what Bwaller said is true.

[Tretnine]

it's alright broshi. I still love you.

[fastbroshi]

   Sinner.

[MRieck]

In the picture of the Yosh pistons you bought it shows four sets of rings including a three piece oil ring, are you not planning to use these?

My thought earlier. I never had problems with Yosh 3 piece oil rings

[fastbroshi]

Mike I just saw you updated your sig.  That makes me think of Dr. Evil saying it.  "Yes my CB cost me....(dramatic music)....One Billion Dollars!!"

[MRieck]

Mike I just saw you updated your sig.  That makes me think of Dr. Evil saying it.  "Yes my CB cost me....(dramatic music)....One Billion Dollars!!"

Exactly. I have to speak with you about your project. PM me a phone#. Thanks!
 Mike

[Hannibal Smith]

Look, I 'aint gonna lie-

CrazyPj is undoubtedly right about us not knowing crap, and converting to 3 piece is for chumps, but..................I totally understand the 3 piece oil ring, and know how the system works. The 1 piece is foreign territory to me, and I don't know crap about 'em.

I just can't win.

[Tretnine]

Speaking of projects mike, I PMed you the other day... you didn't forget me, did you?  Since we're all off topic anyway, have you got an idea of what kind of compression numbers yosh racing pistons are going to give me?

[lordwhimsey]

I took my Henry Abe 61mm pistons into the local machine shop yesterday to have the oil ring groove enlarged to take the stock CB750 3-piece oil rings. The fact that I immediately snapped one of the one-peice rings hastened this decision!

I got some Riken rings from David Silver for £14 a set. I compared them with some NOS Honda and to my completely untrained eye the quality seems the same. I can't believe that Yoshi rings would be any worse quality.

Bear in mind that the groves on the Yoshi pistons may already be the right width for Honda rings if you wanted to use them instead.