Author Topic: More wetsumping  (Read 5257 times)

Online bsa-bill

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Re: More wetsumping
« Reply #30 on: 22.11. 2009 18:19 »
it might go around at half crankshaft speed but how many holes does it have in it ????
enquiring minds need to know ;)

All the best - Bill
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Online Triton Thrasher

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Re: More wetsumping
« Reply #31 on: 22.11. 2009 20:30 »
If that's the case why run at half crankshaft speed not full?

Because it's easier to fit somewhere around the camshaft.  Do the holes line up once every crank rev, as the pistons come down?

Online chaterlea25

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Re: More wetsumping
« Reply #32 on: 22.11. 2009 20:43 »
HI Bill And rustynuts
Bill, I dont think less than 20 ml will make much differ between US ans us over here in a 1/4 pint!! LOL

Rusty,
The breather objective is to have a negative crankcase pressure overall, so "timed" are open as pistons are decending
closed on the upstroke (assending)
on a lot of other engines they use a simple flap valve to do the same thing!!!!
Cheers
John O R
1961 Super Rocket
1963 RGS (ongoing)

Offline Rusty nuts

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Re: More wetsumping
« Reply #33 on: 22.11. 2009 20:52 »
Bill there's one hole & I think John O R answers TT's?
1949 A7 Plunger
1947 A7 Rigid Star Twin
1969 Triumph T120R
1972 Triumph T120V

Online bsa-bill

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Re: More wetsumping
« Reply #34 on: 22.11. 2009 21:18 »
Well it's been a while since I built my timing side up ( this project has taken 5 years so far - hangs head in shame ) but I rather thought there where two holes in it so that one of them lined up every crank revolution with the breather exit gallery,  could be wrong though I know I'm often wrong SWMBO tells me so.
Now here's a thought, I remember when fitting up the breather that if the thickest cork gasket was used the dowel on the camshaft pinion has not a lot of contact with the breather, has it ever been known for the cam pinion to lose contact with the breather ????.
This would put the timing of the breather out with what consequences ??

All the best - Bill
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Offline blackbikemike

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Re: More wetsumping
« Reply #35 on: 23.11. 2009 11:05 »
Once again thanks for all your input. I haven't done any more since my last post (no time *sad2*), but two more points: The very first time I started it, got lots of smoke from crankcase breather, so obviously clear, but since then minor smoke but good chuffing pressure. My compression tester says 150 psi after a couple of strokes (on both cylinders) so could it still be sticking/incorrect/incorrectly fitted rings? Re amounts of oil, my initial "pint" theory may have been an inadvertent fishermans tale, looking at whats in the tray after three attempts is more like a pint. Also, on removing the exhaust pipe quite a lot of oil is visible in the head, in the pipe, in fact all the way down to the silencer. Any way, I don't think I'm going to get anywhere without stripping down further, so I'll post again once I have *smile*

Offline olev

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Re: More wetsumping
« Reply #36 on: 23.11. 2009 12:10 »
Bill,
I don't think you are right when you reckon you could be wrong.
and I think its just not right for SWMBO to say you are always wrong when some of the time you're right. Its just ... wrong.

The breather is 4" in circumference and has 2 off 3/8" holes opposite each other.
so a point on the breather circumference travels 2" in a full revolution and 1" on the down stroke.
This means breathing occurs for only 3/8 of the down stroke, ranging from a crack to a fully open 3/8" hole.
I also remember reading somewhere (could be on this forum) that there are camshaft pinions with the pins in different locations wrt the timing dots. So some machines may have their crankcase breathing timed different to others.
I still strongly suspect some top end oil leaks are caused by a pressurised crankcase preventing oil returning to the sump so causing it to collect in the rocker covers.
but ... I'm probably wrong.

Online bsa-bill

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Re: More wetsumping
« Reply #37 on: 23.11. 2009 15:06 »
Thank you so much olev, I thought I was right but had no intention of removing a timing cover to prove it.
As for TheyWMBO I recall a mail I once had from one of you countrymen when I was bemoaning how my wife came down to the shed and took my mind off what I was doing resulting in a cracked rocker box ( left the comb in and tightened it down - DOH )
His remark was "If your wife can get in your shed her chains to long" not very PC but I do love Ausie humour.

Yes I also recall the mail re the pin on the breather

All the best - Bill
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Online chaterlea25

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Re: More wetsumping
« Reply #38 on: 23.11. 2009 18:55 »
Olev,
What about the breather sleeve going from fully open to the closed position??
3/8 + 3/8 = 3/4 in.
One inch travel for half  revolution of the crank,
since the volume changes most at mid stroke it makes sence for the holes to be lined up at this position
Or am I losing the plot???
Cheers
John
1961 Super Rocket
1963 RGS (ongoing)

Offline Rusty nuts

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Re: More wetsumping
« Reply #39 on: 23.11. 2009 20:45 »
Bill there's one hole

I looked at the breather I intend(ed) to use in the new project, it has one hole, it also, I have discovered today doesn't exactly fit the inner timer cover it's mean't to unless you're willing to the use a soft drift! Came in several boxes of bits with the plunger & I assumed! Oh look, a breather may come in handy one day!
God knows what it's from, can't remember what went in the plunger but that did at least did fit & it runs fine so I'm in no hurry to go look.
Until my memory improves I shall stick to less technical posts.
Still think 1/2 a pint is acceptable though!!!
1949 A7 Plunger
1947 A7 Rigid Star Twin
1969 Triumph T120R
1972 Triumph T120V

Offline blackbikemike

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Re: More wetsumping
« Reply #40 on: 24.11. 2009 14:36 »
Ok, got the pump off today, a little too easily I think! I took off the stud nuts, and one came happily out with the stud attached. attempting to undo the locknut (LH thread) I could feel the pump moving, not just in and out, but very fractionally up and down. Further inspection showed that the studs were only finger tight, (though the locknuts WERE tight) so I'm wondering if this could be part of the problem? Gave the non return valve ball bearing a bit of a poke while I was in there, and that seems to be free and moving on it's spring. The pump looks OK (I think) I have included a photo. Another slight puzzle, I rotated the drive easily with my finger, then took off the end cover to inpect the cogs (fine), I didn't remove the screws, left them in the cover, so they'd go back in same holes, but once I'd tightened it up again, I couldn't spin the drive with my finger! I'm assuming once the drive is being driven by the crank it will turn easily, but maybe if the pump WAS loose, it will surely have worn the pump drive and crank drive.If the pump was loose, could this be causing the problem, but if so, how? Also removed union bolts from rocker boxes, apertures look the same size to me (see photo). Leaving it apart for the time being whilst back at drawing board! PS, should I loctite the pump studs?

Online bsa-bill

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Re: More wetsumping
« Reply #41 on: 24.11. 2009 18:01 »
Rocker feed bolts are different lengths? I think they should be the same and although the holes look about right size ( I think they should be 3/64 ") because they are different one or both may be wrong.

Pump being loose could be causing problems, if you could move your timing case cover up and down a bit you would expect it to leak, however as your engine did not seize that suggests that the feed side was at least getting enough oil to all the important bits, the return side leaking is a different matter though, for all it has more capacity than the feed side any oil escaping is defeating this and this escaped oil might well slowly build up in quantity.

Other members might like to comment on the rocker feed bolt holes as I'm not certain about the size.

All the best - Bill
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Offline Rusty nuts

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Re: More wetsumping
« Reply #42 on: 24.11. 2009 20:25 »
Rocker feed bolts are different lengths?
Doubt that makes any difference as oil is fed through those holes into the centre of bolts & into rocker spindles
Is there oil pooling inside the rocker boxes if not it must be rings.
1949 A7 Plunger
1947 A7 Rigid Star Twin
1969 Triumph T120R
1972 Triumph T120V

Offline A10Boy

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Re: More wetsumping
« Reply #43 on: 24.11. 2009 20:29 »
Quote
Sorry Bill I have to disagree, If the sump is almost empty except clinging oil you'd have a serious problem, more than likely a seized engine, it is not only the big ends etc that require oil, the camshaft (certainy long stroke engines as they do not have a trough) & more importantly cylinder bores rely on oil throw/pressurised mist from the crank, without it they'd seize.
Also acts as a coolant.

Rusty, sorry but the premise of your "theory" is wrong. You seem to think that an [almost] empty sump will cause bad oil flow and result in a seized engine - incorrect. Oil to lubricate the engine is fed via the pump from the oil tank, - not the sump.

Cars store their oil in the sump, a "Wetsump System", and if this was empty, seizure would be certain. Our BSAs have a seperate oiltank, this is known as a "Drysump System", called that as no oil is stored in the sump, - in fact that is why when it goes wrong and oil fills the sump its known as "Wetsumping"

The oil system is designed intentionally so that the scavenge side of the pump has a higher output than the supply side to ensure that the minimum amount of oil is retained in the sump,- its pumped back to the oiltank where it belongs, this is the reason why the end of the scavenge pipe is so low in the sump plate. If "used" oil wasn't cleared, it would be blown out of the breather etc.

Bill is entirely correct when he says that the only oil [which should remain] in the sump is that which drains down from the wet engine when its stopped.
Regards

Andy

1960 A10 - Black Golden Flash
Plus
1974 Kawasaki Z1a
Yam XJR 1300

Offline Rusty nuts

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Re: More wetsumping
« Reply #44 on: 24.11. 2009 20:47 »
Thank you, I understand all principles involved.
I never said anything about" bad oil flow"
 I did not imply that oil should be stored merely that there is inevitably some residual oil to be found in the sump at any given time & that 1 pint is abnormal  
half to a quarter is acceptable & a dribble is IMHO not.
If you've go a bike that doesn't blow oil out of the breather ever, that is one exceptional bike.
1949 A7 Plunger
1947 A7 Rigid Star Twin
1969 Triumph T120R
1972 Triumph T120V