BSA Owners' Club Forum

The BSA Workshop => Twins => Topic started by: bobandbec on 21 March, 2017, 23:08:11

Title: Engine tear down
Post by: bobandbec on 21 March, 2017, 23:08:11
I have an early 1962 A65 Star (amongst others) and have owned it for about 2 years. It has very good oil return, does not wet sump and, for its age, goes pretty well on the road, in fact good in third and fourth gears.
I fitted an external oil filter when I first got the bike.
Over the Winter I took oil pipes, oil tank off and cleaned thoroughly. There was quite a lot of sludge in the oil tank.
I don't have history on the bike but it is the original engine as per the BSA records.
What do people think about checking of the sludge trap, big ends, crank,, etc. for a bike which runs OK? What are the criteria that would make someone decide to have a tear down and rebuild of the engine? or is it leave well enough alone?
Thanks
Title: Re: Engine tear down
Post by: STAR TWIN on 22 March, 2017, 06:34:06
In my younger days I stripped and rebuilt engines far too often and pretty much invariably pointlessly. Oil tanks are prone to collect sludge - in fact it could be argued that they are designed to do it. The manuals state that the oil tank should be cleaned out at regular intervals. So clean out the tank, change the oil reasonably regularly - particularly if you do a lot of short runs - and keep on riding. 
Title: Re: Engine tear down
Post by: Mike Farmer on 22 March, 2017, 09:29:23
Hi. 

Essentially  I agree with previous assessment unless you have reason to be concerned. If that's the case then my first course of action would be to run it for a few?? miles (or just run the engine) with Flushing Oil. But I would have to be seriously concerned.

Mike
Title: Re: Engine tear down
Post by: Bess on 22 March, 2017, 09:48:05
Hi,
     My criteria for a rebuild is obvious engine noise related to the crank bearings, main and big ends. If so, I fit a pressure gauge and if am happy with the oil pressure when the oil is warm I continue riding. The engines I've stripped have had about 50% of the sludge trap filled with muck which did not impede the oil flow.

From memory the oil pressure switch operates above 5 psi and the oil pressure relief valve is set at 50 psi.

Best wishes....
Title: Re: Engine tear down
Post by: bobandbec on 22 March, 2017, 11:56:36
Thank you for these replies.

I only do about 750 miles a year on each of my BSA's and the oil and external filters are changed before putting them to bed for the darker months.
Seems the consensus is to keep riding unless there are any unusual sounds coming from the engine. One benefit of having three bikes is that it is possible to compare between them.
The A65 Star is my favourite and probably gets a bit more riding and care than the A10 and A50.
Thanks again.
Title: Re: Engine tear down
Post by: EDDIE SIMPSON on 22 March, 2017, 12:00:38
sorry mike, i dont think flushing oil would be a good idea as the sludge trap is designed to collect debris and if that was disturbed the next port of call would be the big end journals. every sludge trap i ve had apart has always had something in it and the biggest threat is non use when the oil turns solid and powdery but personally i would chance that a previous owners already cleaned it out and use the bike. i am sure its been cleaned out sometime between now and 1962 .at least use it for this summer if it arrives.
Title: Re: Engine tear down
Post by: STAR TWIN on 22 March, 2017, 14:08:40
As Eddie says, avoid the flushing oil. I once wrecked an Enfield by flushing it. It loosened a bit of debris which then cunningly blocked an oilway. I would recommend just using a reputable multigrade. 
Title: Re: Engine tear down
Post by: Mike Farmer on 22 March, 2017, 17:14:35
Hi gents.

I bow to your experience. Must say that, maybe luckily, I.ve never had a problem with it. But with serious after thought I would probably agree.

Mike
Title: Re: Engine tear down
Post by: bobandbec on 22 March, 2017, 23:18:33
I use the Morris Classic 20/50 in all three bikes with the Champion H101 filter in the return. The Morris is used for the gearbox as well, rightly or wrongly? Even filled the forks with it when I did the front forks and head bearing on the Star over the Winter.
Title: Re: Engine tear down
Post by: STAR TWIN on 23 March, 2017, 07:24:54
One oil for everything - I am almost as bad. Tractor universal 10-30 is in my primary chaincases and forks. The lighter weight oil seems to make the fork action a bit more supple.
20-50 is probably fine in the gearbox but I use Morris's classic gear oil. Gearboxes are sturdy things and generally behave as long as there is oil in them. It's not as though we are putting massive torque through them.