Honda-SOHC

SOHC.co.uk Forums => CB350/400 => Topic started by: watty51 on February 02, 2021, 07:29:50 PM

Title: Piston ring
Post by: watty51 on February 02, 2021, 07:29:50 PM

Hi all,
Was trying to find out some information about the top piston ring from a Cb350f.

The oil ring and the 2nd (middle ring) have a T stamped on them, but the top ring has no T stamped.

One thing I noticed was there is a slight raised edge on this ring.

Should there be this raised edge ?

If so does it matter which way the ring goes, when reinstalled. Did take photos but lost them on my phone.

Top 2 rings in photo 1 have a T stamped on them, but the ring on its own has no stamp.
Photo 2 showing the edge on top ring.

Thanks
Mark

Title: Re: Piston ring
Post by: K2-K6 on February 02, 2021, 08:02:40 PM

Look at the top of the piston,  the crown often has it's edge smaller diameter than the skirt (next "ledge" down) which accommodates the upturned ring cross section. 

Ordinarily the lip  then is oriented upwards as it promotes the ring sealing against the bore under compression to create a semi dynamic one way sealing effect with the compression acting directly onto the ring itself to push it outward.

Ooh,  that's a long sentence that I can't readily see how to punctuate  ;D

Title: Re: Piston ring
Post by: Nurse Julie on February 02, 2021, 08:35:05 PM

This is the orientation of the top ring. Top is facing upwards.

[attachimg=1]

Title: Re: Piston ring
Post by: Nurse Julie on February 02, 2021, 08:37:33 PM

And here is an exploded view of the end of the ring. Once again, facing upwards.

[attachimg=1]

Title: Re: Piston ring
Post by: Nurse Julie on February 02, 2021, 08:45:09 PM

If they are oversize rings, the size markings will be on the top ring and this should face upwards.

Title: Re: Piston ring
Post by: Bryanj on February 02, 2021, 11:55:57 PM

That top ring is showing typical wear and should not look like that, the pic Julie put up is what it should look like. No size marked means they should be standard and as others have said all markings face up

Title: Re: Piston ring
Post by: watty51 on February 03, 2021, 08:41:18 PM

Thanks for the info...

I think the best way forward is to buy some new std piston rings..

Genuine ones are about £40 per set from David Silver America + postage....

Cmsnl are showing after market ones at about £15 per set + postage (probably more than the parts )has anyone used any of these piston rings with success.

Noticed cruzin have some as well so that’s another option

Anyone recommend a particular supplier

Title: Re: Piston ring
Post by: Nurse Julie on February 03, 2021, 08:42:34 PM

Cruzinimage pistons / rings are great. We use them regularly.

Title: Re: Piston ring
Post by: watty51 on February 03, 2021, 10:22:52 PM

Thanks Julie, I’ll take your advice.