Hello good guys,

Here is a long story, many photos, (Just cause we like them ) and one question at the end:

I have a NOS cases, Ian says it is from the 50's.
It had a NOS bearings in it, but there was bit of oxidation at the contact points
Between the rollers or balls with the outer race, so again, I followed Mr Write's advice, and decided to replace them all with a NNS. (New New Stock)

The first part went well- the drive side:

I boiled the cases, hit the old bearings out, and punched in a new sealed bearing-


Took off the inner seal-


I took the advice of filling a circlip to replace the original-


And locked it-




I was happy to finish with the drive side-



OK,
Now I boiled the timing side of the cases,



Hit the original bearings out,
And prepared the Timing side ball bearing, as for the thech' section: RLS7
But it did not look anything like the bearing I took out…





(I did not take it out of the bag, cause I want to try exchange it at the store)

But the new one is smaller, clearly…





Any thoughts?..

Cheers,
Noam.

email (option): noam10@gmail.com

It seems the information in the tech section is incorrect...

I think it should be an RMS7 bearing, not an RLS7 bearing...

An RMS7 is 2 1/4"o.d. x 7/8"i.d. x 11/16" wide..The RLS7 is only 2"o.d....I'll double check the RMS7 to confirm...

Don't worry though Noam...You only have one...I have 15 at the moment... ...I'm not really sure how that happened.. ...Ian

email (option): ian@wright52.plus.com

Ignore the last post...That's not right either...(apart from me having 15 of the wrong bearing )...

An MRJ 3/4J (RHP) or equivalent is what's needed...

My bearing equivalents info. is in the workshop so I won't be able to come up with any other numbers till tomorrow....Ian

email (option): ian@wright52.plus.com

Thanks a lot Ian.

So you have 15 of them, ha?..
Did you use the tech' section?..

I found that the bearing should be
( 7/8 x 2 1/4 x 11/16” ) MJ7/8

And then I found that:

" MJ7/8 Imperial Open Deep Groove Ball Bearing 7/8x2-1/4x11/16 inch
Also Known As: RMS7"
And also "SKF RMS7, FAG MS-9"

So I think your first reply was correct: RMS7, not RLS7,

But I will wait for your confirmation.

Cheers,
Noam.

email (option): noam10@gmail.com

Could that be the RHP MJ7/8J ?

Henk

email (option): ahum@quicknet.nl

Hi Henk,

I edited my last post, after finding

"RHP MJ 7/8", Single Row Radial Bearing ( see SKF RMS7, FAG MS-9)"
But with no second "J" at the end (MJ7/8)...
I don't know what the last J stands for.. (MJ7/8J)

Noam.

email (option): noam10@gmail.com

Thanks Noam,

I have made put these numbers on the bearing page.

Henk

email (option): ahum@quicknet.nl

email (option): noam10@gmail.com

The last 'J' is the cage type...

I think I'm loosing it...first I put the wrong info. on the 'tech section'..Then (much later) I bought 15 of the wrong bearing...and finally I got the wrong answer in reply to Noams post...

Other than that it was all 'spot on'...

I obviously haven't worked on these engines before... ...Ian

email (option): ian@wright52.plus.com

Mmmm boiled crankcase, no doubt with roast greased chain and simmered piston followed by frozen gudgeon pin. Yummy!

It sounds delicious Keith !

Its OK Ian, you know so much, that even forgetting, you still know
More than most of us will ever learn on the bikes..

I took the wrong bearings to the shop where I bought it,
Thinking to try my luck getting a refund for it, and buy the correct ones. (I had 2)
When I started to explain my mistake, (Don't worry Ian, I did not mention your name...)
The guy, to my surprise, just said-"Hey, you don't have to give excuses.
Where are the wrong bearings? give them to me !"

He took the old ones, gave me 2 of the correct ones,
And after a full refund, I had to add about 6.5 Pounds / 8 Euro for the exchange.

The new bearings are Japanese (Sorry.. ) Seiko,
So at least the engine would keep the time correctly..

THANKS FOR THE HELP !

Noam.

By the way,
Just as you said Ian, I asked the seller at the shop regarding the "J"
At the end, and he explained that it stands for the outer race material-
Metal, bronze et cetera.

email (option): noam10@gmail.com

Sorry guys, only just seen this one.
Ian is spot on that the suffix 'J' refers to the twin ribbon cage which surrounds the balls in the bearing.
Quite right Noam on the new bearing, it can be called allsorts of references, but is basically an MJ 7/8 ( originally Medium Journal, as opposed to light LJ, extra light XLJ, but goodness knows who thought of KLNJ ??)

The brand that you have there, KSM is a decent quality bearing. I have supplied them for over twenty years and never had a fault, so no worries there either.

You can get them in a sealed version too, which you could take out the inner seal again, so I assume that is what you will do.
Darren

email (option): dwrudd at lineone.net

Hi Darren,

Thanks for the info !

Regarding the last part:

"You can get them in a sealed version too, which you could take out the inner seal again, so I assume that is what you will do."

Do you recommend to use a 2RS sealed bearing also where I put in new one
(Timing side ball bearing) with the inner seal (the one close to the timing) off?...

Thanks,
Noam.

email (option): noam10@gmail.com

No need to fit a sealed bearing in that location as leakage past the bearing has no effect...

On the drive side a sealed bearing reduces oil leakage into the primary cases should the engine 'drop' its oil into the crankcase...Ian

email (option): ian@wright52.plus.com

Wot he said
Darren

email (option): dwrudd at lineone.net

Thanks you both!

That's what I thought, or even that having the 2 T/S bearings vented
Would even be better for oiling the bearings, rather than if sealed.

That's why I asked..

Cheers,
Noam.

email (option): noam10@gmail.com