750J O Ring

Post your Kettle problems here and cures
Post Reply
klektermaniac
Posts: 92
Joined: Sat Oct 25, 2014 8:54 am
Location: Lincolnshire

750J O Ring

Post by klektermaniac »

Hello All,
I am just ready to fit top & bottom crankcase halves together and have a question. My Haynes manual - Section 35 paragraph 2 states - "...….fit the small O ring into the recess to the rear of the mainshaft assembly".

My question is what O-ring???

The manual does not show it in any of the pictures or give any more details, and I have re-read my strip down notes and I did not make any reference to an O ring in my log or photos.

Can anyone please help before I put the crancase halves together?

RogerH.
bod750
Posts: 292
Joined: Mon Feb 01, 2010 1:08 pm
Location: Isle of Sheppey, Kent
Contact:

Re: 750J O Ring

Post by bod750 »

Hi Roger, is it the water bypass 'O' ring?

when I rebuilt my engine put the crankcase
halves together then could not remember
if i put it in, took it apart again to find
I had put it in.

Steve
summer0123
Posts: 52
Joined: Tue Nov 17, 2015 2:58 pm
Location: Neath, South Wales

Re: 750J O Ring

Post by summer0123 »

That will be the o ring which seals the cooling water jacket between the top and bottom casings. If you look on page 56 (Hayes Manual) you will see a photo of it.
Barry sells them on E bay.
Paul
klektermaniac
Posts: 92
Joined: Sat Oct 25, 2014 8:54 am
Location: Lincolnshire

Re: 750J O Ring

Post by klektermaniac »

Hello Guys,
Thanks for the quick replies - I should have the O ring as I have a full gasket and O ring set.
Back to the shed and onwards.
Thanks,
RogerH.
User avatar
BATTS
Posts: 441
Joined: Sun Jul 15, 2012 6:47 pm
Location: Lancashire

Re: 750J O Ring

Post by BATTS »

I didn’t think the J had the sealing O ring was it not introduced at some point in the K production?
Chris
76 GT750, 78 GT550, BMW K1600gtl
klektermaniac
Posts: 92
Joined: Sat Oct 25, 2014 8:54 am
Location: Lincolnshire

Re: 750J O Ring

Post by klektermaniac »

Hello,
I think you may be correct BATTS as my engine does not look the same as the picture on page 56 of the Haynes manual.
On my J engine the hole is an oval shape with NO recess, so the O ring would not fit anyway.
I think a little bit more Bond 4 around this area may be the answer.
RogerH.
teazer
Posts: 1035
Joined: Mon Mar 07, 2011 8:10 pm
Location: Chicago

Re: 750J O Ring

Post by teazer »

J and most K models did not have the O ring. It was changed at engine number 36198. As far as I can determine, at that same change the engine number changed from the raised boss above the clutch to the left side above the chain run.

It may be possible to machine the lower case to take an O ring to prevent water ingress into the transmission. Later models had a slightly different casting in that area, so you may have to use a different O ring.

Or use more 3 bond and keep your fingers crossed.
Post Reply