Britbike forum Forums British Motorcycle specific Brands Bsa bulletin board A65 Timing Side Bush - Recommendations in QLD Aus?

Hi All,

Rebuilding an A65 and wondering if any Aussies can recommend any machine shops with experience doing
A65 Timing side bush's?

I'm on the Gold Coast, QLD closer the better.

Cheers

Check with the BSA Club up there, or Mike Reilly.

BJ's Bikes and Bits can probably help as well.

There are a few blokes from your area on the forum with unit twins as well, so they might have recent contacts.

BJ's haven't done mechanical for ages, He's looking to sell up.

These days it's no more expensive to do an end feed and needle setup.
However, if you need to do a re bush, you'll need to get the crank ground
so it's round and then find someone with a reasonable size mill and a
boring head that can size the bush for you once it's fitted.

Know anyone in Aus doing these conversions?

I can supply instructions but the guy i use is not interested in doing them commercially.
He's done a few for me but he's retired now and doesn't want to go back into business.
You just need someone with a lathe and a mill. Not rocket science. If you can find a tame
friend with the machines the job is straightforward.

There's a bit of alloy welding involved as well, isn't there?

I'd certainly be interested in your instructions on how to do the job, for one of my own engines. I have the gear, but not the expertise to take on anybody else's motor.

Yep most good motorcycle engineers seem to be getting out of it.

Keen on whatever instructions you want to share

This is so true about the cost. And the good thing is if you need to replace the bearing in the future, it can be done by the average DIY engine builder/home mechanic. Though whilst the work isn’t hard for anyone who is competent with a milling machine, I find many good engineers don’t want to take on the work with drilling the crank case and putting the aluminium snail (if you want the SRM look) one the inner timing case.

Do not weld the inner cover unless you have a spare! They always distort unless jigged.
There is no need to weld the inner cover anyway, you can still do a hidden version without
welding. You just need to bore the case and inner cover accurately, to do this you need a mill.
Years ago, back in the uk i had 3 very good welders try to get the covers done, they all distorted
by differing degrees, one was usable. I've since done around 10 or so conversions without welding.
If you turn up the seal holder block well, it's a tight fit in the cover and an o-ring will seal it, you need
a couple of small screws to retain it, there is little load on it.

https://imgur.com/a/U33nwox

There are a few points to confirm.

What bearing you have on the drive side. Ball or roller.
What bearing you use on the timing side. With a ball race drive side you just need a normal 30mm id needle race.
You can use the combination bearing if you have a roller on the drive side.
Bore the case for the selected bearing, pilot drill the inner cover fitted at the bearing centre and at the upper oil pump stud.
You continue the oil gallery drilling into the base of the oil pump stud and make a hollow stud to provide the feed.
Block off the original bush oil feed with a 6mm grub screw or a plug.
Turn the crank timing side journal and fit the needle inner race. This varies with the selected bearing. Normally 30mm.
Drill the end of the crank and press fit a 10mm od quill for the feed.
Ask questions if you need more info.

https://imgur.com/a/T51qCuw

Thanks, Nick. That's going straight to the pool room.

Great information Nick!

Out of curiosity, is there a reason you break into the oil pump feed instead of breaking though into the feed to the oprv like the Devimead/SRM way? Or is this to avoid welding the case?

Out of interest (and feel free to laugh) would something like lumiweld not work on the inner timing case? Whilst it can get hot enough to melt the parent metal, I don’t think I have ever distorted anything with it. Or would it be porous in this application?

Interestingly I have an inner timing cover SRM Type (which doesn’t leak) and came off a bike which had the conversion and a series of other bodges.

Making a hollow oil pump stud is just neat and avoids welding.
The non return ball/spring valve is also retained.
Both the turret it fits into and the oil seal holder could be soldered
using that lumiweld if you are confident/competent with it. I've not
used it so i'm not.........

The one in the picture is an A10 crank and just uses an NA5906 bearing
as the end float is controlled by the drive side ball race.
It has an 8mm/5/16 oil pump top hollow stud. An 8mm seal was used on
the crank end feed but normally a 10x18x7 is easier to get. The seal does
have a circlip retaining it but you can just use a couple of washers on the
quill as shown in the photo.
I like to have a 4mm diameter min oil feed size all through the fittings.
I suppose you could paint the assembly and make it look a lot more
presentable than it is but it's not seen so who worries?

Actually Alllan, you could make the turret and the seal block from alley if you
were using that Lumiwed, i use brass and copper as it's silver soldered together.

A few points on the machining......

To bore the case for the bearing you must set the cases up on the mill as a pair.
Use the drive side bearing outer to clock from. The joint flange of the cases is
the level datum NOT the timing side face, they are seldom parallel.
Once the bearing hole is sized the inner timing cover can be fitted and the centre
for the seal holder block can be marked and pilot drilled. The upper oil pump stud
comes all the way into the case so after it's removal a small grub screw will need
to be fitted to plug it. The new stud need only tap into the case by 10mm or so,
this varies from case to case. 8mm or 5/16unc is fine for the stud thread.
A long series 4.5mm drill can be used to extend the gallery up to the oil pump
stud base by removing the plug by the base of the relief valve. The oil pump
upper stud hole will need drilling out to accept the 8mm hollow stud.
Due to the fact that the cases and covers are 'all sorts of shapes and sizes'! a
drawing of drilling the cover can't be done. The cases must be converted as a
set really. When doing the job you will realise what total and utter [***] is spoken
about line boring the standard bush assembly, it's impossible to take them apart
and re-assemble them better than within a couple of thou. One dowel and half a
dozen bolts just won't do it.
When boring the bearing hole to size a 2mm or so lip can be left on the case to retain
the bearing and a thin bronze thrust washer can be used to set the crank central,
this will also prevent the drive side bearing from being pulled over when hot.
If using the combination bearing NK1B5906 end float is controlled by the new bearing.

Yes....And because of that I've taken to doing my bearing sizing and final crankcase button up with the cylinder bolted on snugly believing it will encourage the cases to align where they naturally want to be. It must cut down on flexing and it really seems to reduce those stray oil weeps here and there.

But I'm not sure this idea would really help on the mill table because of all the possible bumping and clunking around that could move your setup. Anyhow, that's my 2c worth.

BTW, I really like that idea of the hollow oil pump stud. Simple and elegant.