A65 barrels

[Tjwood]

Hi. I'm still looking for a set of barrels for my 1968 A65 engine. The parts book says that the part number starts with '68' but the only A65 barrels I can find (on eBay or elsewhere) have a part number that starts with '71'. I'm guessing that the barrels with a '71' number are for engines made after 1970 . I've been told (rightly or wrongly) that two of the bolt holes were spaced differently on barrels made after 1970 so they won't fit my engine. Any confirmation or denial of that would be useful to know.
Thanks
Regards
Tony

[chaz]

do you mean the part numbers on the castings?

this will be the casting number, the complete painted and machined barrels will be a different number.

[Tjwood]

Hi. Thanks for your reply. What I'm trying to establish is whether a barrel that has the number 71-1033 stamped into it will fit onto a 1968 crankcase and cylinder head, given the differences in bolt diameters (5/16 vs 3/8) and bolt spacing. I'm new to BSAs so getting the correct barrel is proving challenging as my knowledge is limited to what I can glean from the internet.
Thanks
Tony

[chaz]

my Roy Bacon twins book is at my unit.
maybe someone has one to hand that can look in the back to check part numbers, might possibly help.

the only other check would be checking individual parts books to see if any differences.
1968 68-886  Lightning Spitfire Thunderbolt Firebird  or 68-888 Royal Star  (500)
1967 68-43 L S T H 68-48 for R W (500)
1966     same
1964     same
1969     as 1968
1970    71-1195  L T F   71-1196  R (500)

seems to suggest 68 and 69 the same, 64-67 same and 70-71 same, but its not unknown for changes to part numbers , im finding it with 69 parts at the moment, some Triumph numbering.
maybe just bolt hole diameters, unlike the Triumphs where they went from 8 stud to 9 stud barrels and heads.

[JulianS]

71 1033 is a later barrel.

This one is from a 1971 OIF Lightning.

[Tjwood]

Thanks Julian.
Regards
Tony

[DerekAnderson8]

The later barrels have bigger crankcase stud mounting holes, later barrels will fit earlier crankcases but earlier barrels would need to be drilled to fit later crankcases.

In other words the later barrels will fit but you might have to put the later studs on your crankcases which is a mod that can be done.



derek

[Mike Farmer]

 

I seem to recall that there were collars available to pet on the earlier studs instead of needing to 're stud' with the later size. ?

Mike

[Tjwood]

Thanks guys. I was worried about using a later barrel for three reasons:
1. Would the earlier (1968) cam followers that I've already bought work in the later barrel?
2. Making sure that the later barrel with 3/8 holes wouldn't move around on the 5/16 studs during engine use. If sleeves are available they'll only have a 1/32 wall thickness but I guess they'll be supported by the barrel stud hole walls so should be ok. The only problem now is where to get them - I'll get onto Google.
3. I've read that the two front stud holes in the barrels are in a slightly different pattern on the later barrels and that to use a later barrel on an early crankcase, you have to get the front two holes  elongated - if that's true, it sounds like a major engine job and might not give a good fixing for the nut as it won't be supported by the barrel over its whole circumference.
Thanks again
Tony

[chaz]

the "spacers" hollow dowels are a standard feature on many Japanese bikes, I would not worry about fitting them, I have made some on a lathe where damaged on removal.

[Gup holland]

My engine is from 63, barrel 68-44. 5/16 studs and the 2 backbolts also 5/16.
The head is a lightning 70 head with all 3/8 headbolts. The 2 back are 3/8 bolts with altered thread 5/16.

Gr gup

[Allan G]

If you try and fit a late barrel to an earlier bike, the 2x studs front and centre are spaced differently.

There seems to be a bit of a glut of OIF barrels on eBay at the moment, but they are quite rare compared to an earlier type. 68-44 is quite common, though often need the rear studs for the head changing to 3/8" which isn't difficult.

Be patient. There will be a few early types on the market before you know it.

[Tjwood]

Hi Allan (and everyone who replied). Thanks for your thoughts and comments. Allan, I wish I shared your optimism about the correct barrels turning up on eBay soon. I've been looking for about four months and not seen anything apart from barrels with badly broken fins and/or wrecked bore skirts. However, I'll keep looking!
Regards
Tony

[DerekAnderson8]

I think its very doable to use later barrels on earlier cases, here is an earlier post that explains

https://www.bsaownersclub.co.uk/bsaoc_forum/index.php?topic=11263.0

If you cant get earlier barrels its certainly a route i would go down.



or get a Triumph i have been working on a nice 1965 TR6 and you can get all the parts you need.

[Allan G]

Try these.

It does have one broken fin. But it will be hidden by the down tube or you could have it replaced.