Smokin'

You don't know how true that is ;-)
I reckon I could cobble together a running / rolling bike with the "spare"
parts I have for both the B31
and my "project B33".
Anyroad - my nice shiny black B31 is off for MOT now - you just watch it
piss down with rain in about an hour's time.

 

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

Yebbut, has it stopped the smoking, that's what we're all waiting to hear.

 

OK, assuming the bore, piston and oil rings are good (and that's a big
assumption), the mention of the baffle plate on later engines makes me
think it needs one. It certainly wasn't the first or last engine to have
needed one.

Btw, that 'known good' piston, was it carefully mic'd up?

 

Wotcha.

Has it bollocks ;-)
I'm still awaiting a shiny, new oil pump. . . . . until then, I'll just stop
the engine when unlocking the garage doors.

 

Wotcha.

Hmm. Now that's an idea.
I'll have a play with the spare crankcases and see what can be rigged up.
Preferably something that can be "retro-fitted" without splitting the cases.
It's just that I've never come across a BSA pre-unit single that does this
smoking trick. I know *something* must be causing it, and it's annoying me
that I can't find it. How simple an engine can you get ? . . . . and I
still can't stop it smoking. The oil pump is the only thing that has not
been changed for new. I've fitted spare pumps. Pumps that have been taken
out of non-smoking engines, but that ain't the same as a new one. The new
oil pump is on the way, but I don't know when it will arrive.

Oh yes. Having been caught out by a rogue piston before, this one was given
a good going over. The company that did the re-bore are first rate too.
Having said that, I still measured the bore when I got it back ;-)

I've been out on the bike most of this morning, and it runs quite happily,
no smoking when it's being used. No smoking when ticking over at traffic
lights. It doesn't even smoke on the over-run ( which considering the bore
and piston are new, and the head's been re-conditioned, I wouldn't expect it
to ). But the moment you leave it for thirty seconds or so on the side
stand, the exhaust genie appears. Trouble is, this bloody genie doesn't
grant you three wishes.

Cheers.

 

Wotcha.

And arrive it did. All nice and brand new - even comes with a
"susstificate" to prove that it can deliver one pint of SAE 30 oil in just
over three minutes - and, more importantly, scavenge 1 pint of SAE 30 oil
in just over one minute. The poor unsuspecting B31 was laid over and the
new oil pump fitted - and guess what ? It still bloody smokes. The new
pump promptly came back out - it's going in my all singing, all dancing,
project B33, so it ain't been a waste of money.
The only other thing I've found out about this engine is that it's not as
old as it's supposed to be. According to the engine number, YB31 ****, it
was one of the last made, possibly around 1962 / 1963 - the bike is
registered as 1959. Maybe there was some kind of modification done to the
last engines ?

Anyroad - as far as I'm concerned, the thing can smoke as much as it likes.
I'm just going to use the bike, and should I ever find a way to stop it
smoking when on the sidestand, then all well and good - if not - then so be
it.


Bloody typical. National no-smoking day. Just to rub it in, the B31 smokes
like a chimney - I've packed in smoking - and, to add insult to injury, it's
my birthday as well. Might as well take the bike out for a smoke then ;-)

 

LOL.

 

LOL nice one



-

 

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

No!!!! Surely you can't leave us in smoking-B31-engine limbo misery like
this. <lie>I've been having sleepless nights thinking about it.</lie>

There has to be a reason, and there has to be a cure. You must tell your
wife to feed you only cold food and warm beer, and deny you all sexual
favours until you've sorted it. Don't forget you are doing a public
service here for the good of the B31-headscratching community.

 

<Barwick Green... >

Regards,

Simonm.

 

It's already been said somewhere earlier in the thread.

Try this, from Ken Young:

One other point, some British singles had baffles in the crankcase
throat to limit oil splash, don't know if A: that was the case with
the B31 and B: if so they have been removed. If the baffles were
originally fitted they should be on a BSA parts list for the model.

HTH