BSA Owners' Club Forum

The BSA Workshop => Singles => Topic started by: RED ALEXI on 30 April, 2017, 01:39:54

Title: 69' Starfire O ring for inner right hand cover.
Post by: RED ALEXI on 30 April, 2017, 01:39:54
Hello,

 I'm rebuilding my Starfire engine but can't find out where you can get the O ring that goes in the inner right cover, that seals the main oil passage to the crank. Pretty vital to get this right as otherwise the oil pressure to all my new (and expensive) internals will be zilch. Tried to order this from Draganfly, but nothing on their diagrams. Anyone know the nearest size nitrile ring that'll do the job ? Measures around 7.97 mm O/D, 3.9mm I/D & approx. 1.7 to 2mm thick. Thinking of getting one of those O ring kits with various sizes, but what type - metric or SAE ?
Title: Re: 69' Starfire O ring for inner right hand cover.
Post by: JulianS on 30 April, 2017, 10:02:20
Lots of other dealers to try for the o ring, not all have all their stock on websites, try phoning.

If memory serves me right, when I had a Starfire the o rings came in the gasket sets.

Try C and D Autos or Burton Bike Bits.

The part is 68 0289.

Or with the dimensions you have try "Simply Bearings"

http://simplybearings.co.uk/shop/
Title: Re: 69' Starfire O ring for inner right hand cover.
Post by: RED ALEXI on 30 April, 2017, 16:51:12
Cheers for that sport,

 That link also gives the measurements of 3/16" X 5/16" (4.76mm x 8mm) I take it that's I/D and O/D ? Superseded by BSA 70-9430 . I'll check my gasket set again, but I'm fairly sure that there weren't any in there.

 Regards Al
Title: Re: 69' Starfire O ring for inner right hand cover.
Post by: Bess on 30 April, 2017, 17:15:56
Hi Red,
            Curiously part number 68-0289 is also an o-ring fitted in an A65 oil pump on the oil feed driven gear shaft. I have the measurements as 3/16" ID x 5/16"OD.

p.s. Viton is far superior to Nitrile unless you are driving in extreme low temperatures or wish to save money.

Best wishes...
Title: Re: 69' Starfire O ring for inner right hand cover.
Post by: RED ALEXI on 30 April, 2017, 19:34:55
Thanks very much,

 Any ideas as to cross sectional thickness ? Common thickness for this size O ring is 1/16" (1.5875 mm). I haven't seen any values quoted for this yet. I agree Viton is superior for temperature extremes. Thickness though may well be important when considering the compression of a too thick ring could constrict the tiny oil way and hooray ! Back to square one, a totally stuffed engine.

Title: Re: 69' Starfire O ring for inner right hand cover.
Post by: Bess on 30 April, 2017, 20:38:00
Hi Red,
            If the ID is 3/16" and the OD 5/16" then the thickness is :- 3/16" minus 5/16" divided by 2 equals 1/16" thick....... for the mathematicians ID-OD/2=D  ;) ;)

Best wishes...
Title: Re: 69' Starfire O ring for inner right hand cover.
Post by: RED ALEXI on 30 April, 2017, 21:17:29
Hello,

 Thanks for doing the maths ! Assuming it's a regular section that would be right. I take it is a round cross sectional O ring, and not some weird BSA thickness.

 Cheers A.
Title: Re: 69' Starfire O ring for inner right hand cover.
Post by: Bess on 30 April, 2017, 22:37:16
Hi Red,
             With the info given from this thread you will be okay, part number 68-0289 is an O ring, O rings are round in every way.

As suggested there are other seals similar to O rings but with different cross sections such as quad rings and square rings etc., I haven't seen these in a Starfire or any other Bike I've played with.

Best wishes...
Title: Re: 69' Starfire O ring for inner right hand cover.
Post by: RED ALEXI on 07 May, 2017, 14:21:44
Thanks to Julian and Bess,

 Bought the metric equivalent from http://simplybearings.co.uk/shop/ . Really handy supplier. Got them in viton and quick delivery. Ace 
Title: Re: 69' Starfire O ring for inner right hand cover.
Post by: Bess on 07 May, 2017, 16:43:25
 :) :) :)