Oil tank filter

[Bill ss]

I need to give my bike an oil change but i don't have a socket to fit the drain bolt,doe's anyone know the size,i assume its whitworth.

[duTch]

 'day Bill, what kind of bike is it....? A10/7 Sump stud nuts are 3/8 WW - 7/16 A/F....unless it has Allen heads?

[wilko]

Actually a 7/16th socket wont fit the whitworth. A fraction too small unless the nut is well worn.

[Billybream]

Hi Bill.
If you are talking about a swinging arm oil tank filter the size is 3/4W (7/8 BS), its the same size as the fork top nuts.

[Bill ss]

Hi Bill.
If you are talking about a swinging arm oil tank filter the size is 3/4W (7/8 BS), its the same size as the fork top nuts.

Yes thats the one swinging arm a7 the oil in it is about 30 years old and i don't want to use the bike until the oil is changed.


Allso will i need to take the sump plate off for the oil change?

[Billybream]

The sump plate needs to come off as well.
I would be concerned if the oli is 30 years old, has the engine been run during this time, or just left standing idle.
You will expect to find a lot of sludge to be present in the bottom of the oil tank, and its not easy to flush out.. Main worry will be the sludge trap in the middle of the crank, if its any thing like mine after years of standing it will be completly blocked and prevent oil flow throughout the engine. Worst case would be engine strip down and inspection check up and clean.

[Bill ss]

The sump plate needs to come off as well.
I would be concerned if the oli is 30 years old, has the engine been run during this time, or just left standing idle.
You will expect to find a lot of sludge to be present in the bottom of the oil tank, and its not easy to flush out.. Main worry will be the sludge trap in the middle of the crank, if its any thing like mine after years of standing it will be completly blocked and prevent oil flow throughout the engine. Worst case would be engine strip down and inspection check up and clean.

I was told the engine was a rebuild with 19 miles on it,it has been run recently and the oil is returning to the tank,i think it has mainly stood for the last 30 years.

The last owner died and the family asked the local bike shop to sell it on for them.

[muskrat]

G'day Bill.
Yes remove the sump plate and clean it out. It would also be a good idea to remove the oil tank and give it a GOOD cleanout. Not knowing what has been done it's better to err on the safe side. The sludge trap "should" have been done in the rebuild.
Cheers

[Jules]

I think this is a really good case for using a "flushing" oil - not recognised so much these days but in the old days it was always a good recommendation to clear out the sludge. Get it hot running at no load with a few revs for a while then flush it all out before filling with the good stuff ...

[muskrat]

You come anywhere near my bikes with flushing oil and I'll sic the dog onya. Just kidding mate but.
It will pick up the sludge (grinding paste) in the trap and feed it to the big ends then hone the oil pump. The good "stuff" might need to be 90/140 gearbox oil  No I'm afraid it's the old manual labor to clean it out.
Cheers

[Jules]

Hmmm, very interesting Muskrat, why would "sludge" do that, its "only" emulsefied oil after all, yeah it will have exhaust by products in it to create the mess, but if it has "grinding paste" then the ends are probably well gone anyway, plus if its blocked the oilway kiss goodbye to the bearings anyway  . or are you suggesting that the "flushing oil" would have that kind of stuff in it??
I understand what you are saying though that the only way to be thorough is to pull it all down, but thats not what Bill is really looking to do here, if the bike has only done 19 miles of running then surely just a flush (maybe with good oil  ) then drain and refill??

[bsa-bill]

Hi Jules and Bill
 it's because the bike has only done 19 miles that I would be worried about flushing oil too.
It's the first few miles that will create the small particles of metal from the running in process that the sludge trap will catch, also other than what was said somewhere what  proof is there that the bike has only done 19 miles, has had the engine worked on at all or been stored unused for whatever time.

If it were mine I'd be for putting the cash for flushing oil towards a tear down but know how it is to want to get on the road, suggest you buy some cheap non or low detergent oil, change the oil, give it a short fire up or small run and change the oil again, if it sounds good then enjoy it.
oil that's stood still for 30 years will have gone through many many temp and humidity changes (even in the engine) so will be full of water, water = rust on steel bits (bearing cages, gears, cams and so on)

best of luck with it though - enjoy

[muskrat]

G'day Jules, it also has lots of steel, cast iron, brass and aluminium particles. So after it's washed out of the sludge trap and into the bigends, it's splashed around and into all the bushes. Then it's pumped back to the tank. It's fine enough to pass straight through the tank filter (fly wire) and pumped around again.
I'm all for putting proper oil in and changing it after a good ride (50-100 miles).
I would thoroughly clean the tank first before anything else.
Cheers

Just saw Bill's post. Dito

[Jules]

Good perspective, thanks Bill/Muskie....

[BSA_54A10]

Since becoming a mower mechanic I have inherited an oil suction pump and I would strongly suggest you consider doing the same.
When I think of all the years I have been cutting sections out of a plastic funnel trying to get it to fit under the tank, let alone all of the pans of oil I have put my fat foot into I really can not believe I have been doing it that way for so long.
So do yourself a favour & get a pump it will only cost about 3 times the spannar's price and will turn the second messiest job into a five minutes in your Sunday bests one.