72 BSA Thunderbolt - does it need roller bearing conversion?

[Cornpop]

Hi there,
First time poster on this forum and hopefully plenty more to come.
I have had a lifelong fascination with British bikes through my father and am looking to get into it at the ripe old age of 30. I am interested in a 72 Thunderbolt for sale that looks pretty good and have been informed that it is reliable and starts first or second kick. Primary chain has been replaced and oil pressure gauge Installed. There are 30,000 kms on the clock and the seller has informed me that the roller bearing conversion has not been done. Offer is around 4500 pounds
Is the roller bearing something that will need doing at some point in time? Or is it a red flag that it hasn't?
Any helpful info would be greatly appreciated

[DAVE BRADY]

Hi Cornpop,

If the engine is in good order and the timing side bush is in good order then leave the needle roller conversion until the next rebuild.  It is worth doing if you intend doing a lot of miles and will ensure a very long life for the bottom end.  I personally find an oil pressure gauge a bit of distraction.  The price looks ok but can you post any pictures of it for a better idea of the condition.

Dave.

[LightningAndStarfire]

Hi, with the oil pressure gauge you can get some clues to whether the bush is in a good condition. If it is not oil pressure will be low. Let the engine reach working temperature and check the gauge. IMHO you should have at least 5 psi at idle and another 10 psi per 1000rpm up to 50-60 psi. Another cause for low oil pressure could be worn conrod big ends.

The -72 has the cast iron oil pump which is much preferred to the earlier mazak bodied.

[Cornpop]

Thanks for all your help fellas.
The owner says the bike starts on 95psi and then drops to about 40 odd once warm. He says it's fine but interested to hear others thoughts.

This is the best photo. I know the paint isn't correct on both the tank and frame but I'm not overly fussed on the accuracy of it. Comes with original pipes too.

[DAVE BRADY]

Hi Cornpop,

The oil pressure release valve should open at about 50psi so the initial 95psi seems a bit high but the gauge may not be very accurate but as it settles to 40 when warm seems OK.  The oil being used could also influence the initial start up pressure.  What id the pressure after a run and the engine is  and oil is hot?
Does the bike still have the oil pressure light?  This is set to go off if the pressure drops below 7psi (?) and as mentioned this is the minimum for oil pressure at idle.  This is useful when the engine is very hot after/during a long run as the oil will be at its hottest.
This light should never go off when the engine is running.  If your gauge is accurate enough at low pressures then rely on that or have both.
I suppose other questions when buying a bike could be do I know this bike or some who does.   A recommendation from an unbiased third party is always a good thing and at the end of the day if you like it and want it, buy it.

Dave.

Dave.

[Cornpop]

I will have to find out a bit more information from the seller as all that was said in the blurb is '.fitted an oil gauge .on start pressure is 95psi.after a good run drops to 40 odd. which is fine'
Does that make more sense?
Oil pressure light is still fitted and I suppose he uses this in conjunction with the pressure gauge.
Can't say I know the bike.. but have spoken to him on multiple occasions.. Seems like a genuine kind of bloke (we are both sparkies).
Again, I really appreciate the help.

[DAVE BRADY]

Hi,

Sounds like it should be OK.  Ask a few more questions about use etc. and listen to it running.  A65s can sound a bit rattly due to the cases being like and echo chamber but there should be no clunky noises.  If you can, take a second pair of eyes/ears who may now a bit so that brain and heart have an equal role in the decision.
Let us know how you get on.

Dave.