BSA Owners' Club Forum

The BSA Workshop => Twins => Topic started by: Ken Oaff on 06 May, 2017, 08:00:03

Title: A65 Engine rebuild
Post by: Ken Oaff on 06 May, 2017, 08:00:03
Doing a complete ground up bare metal rebuild of my 71 lightning

Bike has been sitting unused and unloved for 20 plus years

Bodywork wise it was 100% correct but had been repainted the wrong colours at somepoint

Numbers don't match, it has a feb 71 engine and a nov 71 frame ?????

Rebuild will not be to original specs, decided to go down the café racer route, however all original parts will be retained and no original pars will be butchered

Bike was taken off road when a knocking noises started in bottom end , motor still turns over

Anyway getting SRM oil pump and bearing conversion done, balancing crank gas flowing head 3 angle valve grings and fitting mikunis because the amals never ever worked properly when it was running

Bile will have oil filter / cooler / electronic iginition

any suggestions  o any other improvements that can be made to engine whilst its apart, ie lightened flywheel  / drilling gears give any real world improvement
Title: Re: A65 Engine rebuild
Post by: Bess on 06 May, 2017, 10:24:37
Hi Ken,
            I find my rebuilds are finance driven. What I did wasn't whats listed below but if I re mortgaged my house, then:

What you've done +

Change all the bushes
New rocker spindles
Alloy valve guides
High lift cam, new cam followers
New head bolts
Big bore kit
New oil PRV
High strengh push rods
Sump filter kit
New gearbox bearings
Replace worn gearbox parts
New final drive sprocket
Clutch plate conversion and belt drive
Best wishes...
Title: Re: A65 Engine rebuild
Post by: JulianS on 06 May, 2017, 11:58:04
These would be a must for me;

Billet conrods

New flywheel bolts (dont ask - had one let go and smash crankcase on A10, cost a small fortune to put right)

Hex sludge trap plug

I would consider;

Dural valve top collars and the best valve springs I could find and shim to correct fitted length (dont think some of the commonly sold ones are as good as they could be)

Tappet adjusters for allen key.

Good luck
Title: Re: A65 Engine rebuild
Post by: DEAN SOUTHALL on 06 May, 2017, 15:01:38
Electronic ignition....less maintenance
Motobatt battery...stays up forever
Title: Re: A65 Engine rebuild
Post by: Ken Oaff on 06 May, 2017, 17:43:29
Thanks for all the great advice

Except the motobatt battery, wife has one of these on her ducati, even with trickle charger on it lost power over winter ?????

Title: Re: A65 Engine rebuild
Post by: Caulky on 12 May, 2017, 15:12:40
Well my '71 was in a bit of a state.
l sent the head off to be completely overhauled with new valves, seats, etc, to The Cylinderhead Shop.
It needed a re-bore. new pistons, rings etc.
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