BSA A65 engine noises - a closer look at the crank and possible solutions.

I hopefully have a plan forming, as discussed here after I successfully removed the sludge trap plug and found other wear and suspected damage might be easier to put right than first expected.

[@jjrider6758]

You're lucky to have access to such a competent (and accommodating..) engineer that you can trust to carry out the necessary major surgery Paul ! - It will definitely be more interesting from an engineering point of view but for a mere mortal like me with no decent engineering firms nearby any longer, trying to source a decent crank would definitely be more expedient ! - Of course nowadays it's important to show how motorcycle parts can be refurbished and put back into use. you don't get greener than that !..

[@MegaTubescreamer]

its been neglected badly where it needed some proper work that could have prevented all that eccentric wear, but where theres no will or funds its no way ! a shame to see paul, but this is where you come in hey 👍, i look forward to these mission impossible episodes 😊

[@AllSortsOfStuff58]

Carry on Dr Henshaw. We're all eager to see you cure this one...

[@dwansbo]

Originally the timing side bush was lined with white metal they have not been available for many years.Phosphor bronze as a replacement, in use since the 1980s is a compromise not entirely suitable for a pressure fed bearing. The narrow width of the timing side journal adds to the problem. After fitting the bearings into the crankcase they should be assembled without the shaft using the drive side bearing to align a reamer as the inside diameter of the timing bush will get smaller after it is pressed in. If reliable high mileage is desired consider an SRM/Devimede roller bearing conversion to the timing side. It makes a huge difference to BSA /Triumph parallel twins.

[@paulhenshaw4514]

I have rebuilt an engine with SRM conversion which had failed big ends, so it is not a fix everything solution. I have located a NOS timing side bush of the correct materials and, once fitted, the crank journal will be ground to suit it, for the best possible fit.

[@dwansbo]

@@paulhenshaw4514 If the bush is not reamed after it is fitted to the crankcase there is no guarantee it is parallel to the drive side main. An SRM high output oil pump will help maintain oil pressure, it is good practice to fit a new pump during an engine overhaul, an original one is probably not available today. It would also be worth considering drilling the oil gallery close to the relief valve, tapped 3/8th NPT to allow an oil pressure gauge to be fitted. This can be removed during use or for fun I fitted the gauge in the toolbox on my A10, no body noticed the pipe, I wanted to keep original appearance.

[@paulhenshaw4514]

Thanks. This engine already has a pretty new looking SRM oil pump fitted, as for oil pressure gauges, they only add a scare factor - my own A65 has no oil light or gauge, a plain bush as far as I know and it seems to be happy with life.

[@stephencroft6481]

Wow what a head scratcher !

[@hermangibbs8163]

I feel confident all will be well.

[@samjoentess9168]

Great stuff...hooked on this one

[@mikejurcisek3541]

Paul metal spray the low journals and regrind.

[@neilmcintosh1200]

Alternator rotors have a lot to answer for. Particularly with pre-unit Triumphs a small collar welded to the engine sprocket can then be drilled to accept very short pegs to drive an alternator rotor, thus enabling a crank with a shagged keyway to be used. That is providing the movement of the rotor hadn't already caused excessive spline wear.

[@davidmarkwort9711]

Spraywelding might be a solution for the journals, then the bearing would fit perfectly again, the same goes for the end of the shaft. Would mean some mechining, but better than throwing it in the bin.

[@bananabrooks3836]

The latest solution sounds like a more accurate method given a competent machinist. DId Bsa quote a clearance range between a fitted timing bush and the crank for your engineer to measure and work to? I suppose if it was the last savable A65 crank in the world you'd just have to machine it to suit the inner race of the bearing who's outer fits the crankcase aperture.

[@lesmontgomery6498]

Just drill punch marks. Did a65 and a50 work always measure end float on crank. Bsa did have shims to correct . One quarter inch fillet radius is correct for rod journals

[@waiheke109]

Anyone in New Zealand can do this for my 69 t100c with 5k original miles?

[@MrLukealbanese]

I'd have thought some metal spraying would be the way to go. Adam Booth style.

[@Headwind-1]

could you float some braze on it and turn back down maybe . . .

[@delukxy]

Can you use a Speedisleeve on the alternator end? One for a bearing spacer and the other to correct the rotor fit?

[@richardcross7633]

Spiral welding on the primary side?

[@chrislee7817]

Is there a centre drilling in the end of the crank in the chuck?

[@paulhenshaw4514]

Yes there is, but I din't need to use it for what I wanted to find out here.