Smokin'

Sounds like excess oil is accumulating in the case instead of being pumped
back into the oil tank. If so that implies a weak oil pump which cannot
keep up at tickover. Or maybe an internal oil leak putting excess oil
into the crankcase.

 

Wotcha.

Yep - it would seem there is too much oil in there. I can rule out the
internal leak - I've left the bottom off the crankcase for a good few hours
and nothing gets past the pump. I've pulled the pump apart, and even fitted
another one, but still no joy. It's looking like this is just a quirk of
this particular engine. The more I try to cure it, the more puzzled I get.
I've tried just about everything I can think of.

Ah, the pleasures of owing a SOB ;-)

 

Thus spake ^..^ Lone Wolf () unto the assembled multitudes:

Seems odd that your other B31 with a supposedly identical engine doesn't do
this. What about comparing the positioning, shape or design of the oil
pickup in both engines?

 

Thus spake ^..^ Lone Wolf () unto the assembled multitudes:

Have you compared the 'behaviour' and appearance of the oil return with
that of your other B31? i.e. does the oil return on your non-smoking B31
also splutter when the bike is on its sidestand or is it a steady flow?

Do the bikes lean on their sidestands at different angles? Perhaps you
should try swapping the sidestands to see if that makes a difference

 

Will you have to get a £10 smoking licence for this SOB?

 

Wotcha.

One of the first things I tried was the rings. There are some Italian ones
around that are next to useless. I managed to find some genuine Hepolite
ones and promptly fitted 'em. No different at all. Thinking the bore
itself may be suspect ( although nothing measured up as worn, and it already
had a fairly new piston ) I ordered a new piston and had the barrel bored to
suit - .004" clearance. It still smokes.

Cheers.

 

Wotcha.

I've swapped the oil pump from one to the other - it makes no difference.
I've even wondered if the flywheels in the smokey one are of a larger
diameter, but short of pulling the engine apart there ain't an easy way of
measuring 'em.

 

Wotcha.

They both do what they are supposed to. Full flow as the oil is cleared
initially, then plenty of air bubbles as it scavenges correctly.

Hmm - now there's an idea.
The one just might be leaning that little bit too far, thus allowing the
flywheel to dip into the accumulated oil.
<<goes out to the garage>>

Watch this space ;-)

 

Wotcha.

I rather hope it will work similar to the VED - being old and decrepit[1],
they will not levy a tax on it






[1] A bit like the rider, really.

 

Wotcha.

Oh dear - replying to myself now.

I've just been playing at motorbikes ;-)
The smokey one does lean a tad further than the non smokey one.
http://www.lonewolf.me.uk/LWMEimages/angleofdangle.jpg
The yellow one is the smoking machine.

I dragged the thing down to the river, I must admit the temptation to lob
the bugger in was great, but I resisted and performed a little experiment.
With the bike almost vertical, it does smoke a little, but that could be
residual oil in the down pipe.
When on the side stand, smoke starts within less than a minute.
http://www.lonewolf.me.uk/LWMEvideo/smokeyb31.wmv

My next plan of attack is to remove the "sump plate" and see if I can modify
both it and the oil pump pick up.

Once again - watch this space ;-)

 

Wotcha.

Believe me, this has crossed my mind, but short of pulling the engine apart,
there ain't an easy way to measure 'em.

Ah well - back to the garage with it.

 

While I think of it, what did you do about 4-star fuel? Did you get the
head done and if so where did you go?

 

One last thought on differences, do you use the same oil on both?

 

Wotcha.

There's a Texaco garage by me that still sells leaded four star - hell of a
price though.
I don't bother with it, although my mate bungs a few quids worth in his
Starfire every now and again.
I'll get the head done when the valve seats start packing up - same on the
Guzzi, and that's been running for about five or six years now with no ill
effects ( famous last words - you just watch the exhaust valve seat drop out
now ).

 

Wotcha.

Yep - same oil in just about everything I run.

I just happen to have a spare B33 bottom end - which is the same as the B31.
This spare bottom end was sat, upside down on the bench, and used to compare
clearances with the smokey engine. It seems the flywheels are the same
size. Bugger ! I removed the oil pump and made an extension so that it now
reaches to the bottom of the sump plate. The whole plot was put back
together - and the result was a resounding failure Thinking that the
oil may have somehow been getting down the valve guides when the bike was
leaned over, the next move was taking the oil feed from the head and routing
it directly back to the oil tank. No difference at all. I then removed the
sidestand and modified it so that the bike sits more upright. OK - this
hasn't stopped it smoking, but it take a bit longer before it starts now.
I've sourced a new oil pump - so that will be going in as soon as I get it.
My 'project B33' needs a new pump anyway, so it's a win-win situation.

Anyroad - it's getting too chilly to be playing at motorbikes, so I'm
grabbing my tea, then hitting the pub.

 

Thus spake ^..^ Lone Wolf () unto the assembled multitudes:

I notice from your video clip that the idle speed is a lot faster when the
bike is on its side stand. Might that be significant? What if you up the
revs to match the leaning idle speed when the bike is upright?

 

Thus spake Ross () unto the assembled multitudes:

It's 33 years since I touched a BSA but I don't recall any particular
problem removing and refitting a rear wheel.

I think the only problem you need be wary of is the back wheel covered in
oily muck, mostly originating from the engine. That's what used to happen
with my C15 and I have no reason to think a Starfire will behave any
differently

The usual warning about making sure your tyre levers don't repuncture the
tube applies, of course... but I'm sure you already know that.

 

Wotcha.

I deliberately turned the engine speed up - it moves the oil quicker ( to no
avail ) and also lets the bike run for a few minutes longer before the
amount of oil fouls the plug and the whole plot splutters to a halt. It
smokes just as bad if you turn the tickover back to normal when on the
sidestand.

Cheers.

 

Wotcha,

No serious problems. It should be a "quick detach" wheel. Just remove the
spindle and spacer, from the right hand side, and the wheel will pull out.
It's on splines - the sprocket and brake drum remain where they are. Same
back wheel ( more or less ) as early B31 - B33.

 

Wotcha.

No such luxury on BSA pre-unit singles, I'm afraid.

Cheers.