The BSA A7-A10 Forum
Technical (Descriptive Topic Titles - Stay on Topic) => A7 & A10 Engine => Topic started by: RDfella on 21.07. 2018 17:40
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How you guys put up with these A series bikes baffles me. Had many bikes - including several BSA's - during over 50 yrs riding, but never had as much trouble as I'm getting with this '58 G.F.
Bike has been completely rebuilt. Almost concours (except TLS and s/s rims). Engine completely rebuilt - rebore, new bearings, cam, valves, valve seats etc. Had trouble with the oil pump - which you guys kindly pointed me to the oil pump gasket having too-small holes. It then ran fine with substantial oil return flow. Ran it in all for perhaps 20 minutes. No smoke, all OK.
Fast forward. Today, thought I'd take it for its first ride. Drained sump (not much from standing) pumped tyres, add petrol. Started 2nd kick. But the smoke. Jeez, unbelievable. Worse than a smoke bomb. And oil pouring out from, it seems, behind the primary case. I mean pouring out - an egg cup full every two or three seconds. Return to tank is a strong flow and it didn't do this before. I've know wet sumping from bikes being left a while. Either drain the sump or rev it a bit, but this is ten times worse.
As I said, never had so much trouble with any bike. And I haven't even ridden it yet. I'm so pyssed of with it that if this isn't an easy two-minute fix, I'm going to part it out. BTW, I'm an experienced engine designer and rebuilder.
Any ideas, folks?
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Here's a thought: After I'd not ridden my bike for some months I topped up the oil tank and drove 40 miles. Oil PEED out of the breather pipe, (behind the primary case) and converted my left boot into lovely shiny patent leather! Why? Because I'd forgotten that the reason the oil was low in the tank was that it was in the sump. Running the engine, the pump was doing what it is supposed to do. The oil tank overflowed pouring oil out of the breather. It's one of those schoolboy errors that one never forgets, (I hope).
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Flow and return oil pipes reversed. Broken oil control ring or rings upside down.
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Broken oil control ring
had this recently and boy did it smoke
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I'm an experienced engine designer and rebuilder.
Good job you told us.
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Just a check... Pop the sump plate off again and check that the ball in the pick up is not stuck down. I have seen this to pump the oil out the breather (behind the primary).
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i have not been to the pub, did you just undo a drain plug? I did that once some years ago and got a cup full. I started the engine and it poured out of the breather and filled the mag because it was still full, pulled a vacuum I think, the next time I took the plug out I let it drain then kicked it over and got a bucket full.or as above the ball is stoooook
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Gawd, I've got an A10 and with the mag fixed it's been so reliable it's almost boring.
No, I take that back, no bad karma please,not bored at all, reliable is good
Glen
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It's the total rebuild that bothers me. The A series engine is a good, solid, reliable lump. This needs careful investigation. Compression check for starters. Could the oil control rings have broken on replacing the barrels? Is the breather assembled properly? Clearly something was not put together properly.
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Thanks to all who have replied so far. It's not piston rings - even if they were left out it wouldn't be this bad. In fact I'm amazed it didn't foul the plugs. Not oil pipes reversed - they are right and haven't been touched since it ran OK previously. Indeed, nothing has been touched at all, save draining sump to check for wet sumping. Checked oil level in tank and it seemed about right.
Will drop the plate this time and see what gives (it has an alloy sump plate with magnetic drain bung). I've had engines run when wet-sumped many times over the years - usually a bit smokey and sluggish, but this is ridiculous. If you ran it for three seconds you wouldn't see a car behind you. Are these engines prone to this? As stated, have owned many bikes over the years - and still have a few - but never had this much grief with one bike. And do these bikes have a tall first gear? The gearbox and mainshaft sprokets are std. but first is higher than first in my racing B31 with its CR gearbox.
Used to ride a rigid A7 in the early 60's but otherwise my twins have either been vee or Triumph (6t Triton) so am not impressed with this A10.
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G'day RDfella.
Smoking both sides or one? If it didn't foul the plugs with that much smoke I'd say ex valve guides. Were they replaced? And bronze or cast iron?
Cheers
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....... Are these engines prone to this?.......
Generally not, but maybe sometimes... My first thought is as BlackSheep suggests- maybe the breather is not sealing properly.
When I change the oil, I have about 170ml after I drop the sump plate (immediately after a ridearound), I guess that'd be about standard.
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Hi RD,
Ran it in all for perhaps 20 minutes. No smoke, all OK.
Fast forward. Today, thought I'd take it for its first ride
Does that mean you ran the engine for 20 minutes stationary?
Thats well long enough to glaze the bores *eek*
You do not say what oil you used ? the wrong oil can make problems with a "new" engine
+1 on the other replies,
The magnetic drain plug can make the return ball stick if the plate is fitted with the plug near the pickup
Been there and had that happen *problem* *problem*
John
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I can leave the A10 or A7 standing for weeks, months even, and they start without smoking or widdling oil everywhere. These bikes are bog standard and well used. It does sound like you are pressurising the crankcase somehow. As I alluded to previously, once put together properly these engines run and run indefinitely with minimal maintenance. An old bike is only as good as its last rebuild.
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hi R.D, probably a simple fix really these machines are not `Rocket Science` as black sheep says(Clearly something was not put together properly) but patience is required and you being (an experienced engine designer and re builder) should have no problems, good luck, cheers
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How you guys put up with these A series bikes baffles me. Had many bikes - including several BSA's - during over 50 yrs riding, but never had as much trouble as I'm getting with this '58 G.F.
Bike has been completely rebuilt. Almost concours (except TLS and s/s rims). Engine completely rebuilt - rebore, new bearings, cam, valves, valve seats etc. Had trouble with the oil pump - which you guys kindly pointed me to the oil pump gasket having too-small holes. It then ran fine with substantial oil return flow. Ran it in all for perhaps 20 minutes. No smoke, all OK.
Fast forward. Today, thought I'd take it for its first ride. Drained sump (not much from standing) pumped tyres, add petrol. Started 2nd kick. But the smoke. Jeez, unbelievable. Worse than a smoke bomb. And oil pouring out from, it seems, behind the primary case. I mean pouring out - an egg cup full every two or three seconds. Return to tank is a strong flow and it didn't do this before. I've know wet sumping from bikes being left a while. Either drain the sump or rev it a bit, but this is ten times worse.
As I said, never had so much trouble with any bike. And I haven't even ridden it yet. I'm so pyssed of with it that if this isn't an easy two-minute fix, I'm going to part it out. BTW, I'm an experienced engine designer and rebuilder.
Any ideas, folks?
Possibly there is too much oil going to the rocker box? Causes include blocked return pipe in tank, incorrect parts (eg banjo) in the rocker box feed pipe. This could cause the engine to fill with oil.
Blown head gasket? There is gravity fed oil drain hole sealed by the gasket, albeit I don’t a lot of oil would get in the bores from that.
Incorrectly set up timed breather, it’s easy to stuff these up.
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Pressure relief valve ??
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What colour is the smoke?
Here's a story about unexplained white smoke from the exhaust:-
In mid 60s, when young and carefree, my wife and I (then my girlfriend) set off on a newly aquired but 3 year old Golden Flash from Plymouth to Southampton for a holiday. A trip of 160 miles. We got as far as Exeter (45 miles) and we were held up in a traffic jam and when stopped I noticed white smoke billowing past us from behind. So much that I could hardly see the car in front of us. I turned and said 'Somebody's burning oil', then I could see it was billowing out of my A10s twin exhaust. They were both literally belching white or light grey smoke at an alarming rate. Then the traffic queue started moving and so did I. My bike sounded and felt ok so I kept going. After a few miles the smoke suddenly stopped and we carried on for the remaider of the journey (another 100 miles). We tripped around visiting places during the week covering about another 150 miles before returning to Plymouth (another 160 miles), all without a problem. How long my GF had been billowing smoke after we left Plymouth I'll never know.
My guess/assessment of the mysterious white billowing smoke was that the cylinder head was badly coked up by the previous owner with short runs around Plymouth and it was a build up of coke in the head that caught fire causing all the smoke.
I never did get around to investigating it and had that GF for a further 10 years and it ran perfectly all that time without any problems and it covered the journey from Portsmouth on a Friday evening to Plymouth (175 miles) and back again over Sunday night for most weekends for over a year when I was serving in the Marines. I sold it for £75.00 to buy my first car.
(Edit): It was the GF in my profile picture (with big suitcase on carrier) and it was taken on that same journey after we reached Dorchester.
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Thanks guys.
It is often the quirky things that catch us out, which is why these forums are invaluable. Like when after the rebuild I had very little oil flow. Until someone on this site suggested I enlarged the gasket holes. Why? The pump was in great order, and the new gasket lined up with c’case and pump. I followed the advice, enlarged the holes and eureka – oil flow was superb. Weird.
Same with this latest problem. Bike had been standing for months and so I drained the sump before starting. About a cupful. Started up and had to get out of the garage pdq. Never seen smoke like it. Better than a smoke grenade. And the oil leakage!!! An egg cupful every couple of seconds. Spent half an hour mopping up the mess. I have other bikes (B31 & M21 with vee twin engine) which wet-sump if left standing. However, if I run them without draining they smoke, but no more than a two-stroke. And they don’t chuck out oil. So what was going on here? Another A series quirk.
Berger’s reply was the answer. I took the drain plug out again and got about a quart. Why didn’t it come out the first time? And why such chaos just because it’s wet-sumped? These A series certainly have some idiosyncrasies. Now runs without smoke or oil loss once more.
I have over 50yrs experience in engine rebuilding, modification and design, but this bike has been hassle all the way, so guess I start out in a bad frame of mind. Bought it for the frame about 30 yrs ago, but decided not to break it as it was complete. Then last year thought I’d better get around to rebuilding it before I was too old to do so. Frame downtube was cracked so I repaired that and fitted new lugs for the centre stand. Mudguard brackets were all butchered to fit a mis-aligned mudguard. Engine cases weren’t a pair so I had to machine them and line-bore the cam bushes. Crankshaft drive-side bearing had been staked to create a press fit. Arrggh. I rebored the cylinders only to find the bores weren’t perpendicular to the face and had to bore another .020” to clean up. Head needed valve seat inserts, but no-one seemed to know valve seat depth, so I had to calculate that from valve stem protrusion. Gearbox: layshaft was bent and worn. I straightened the shaft and ground the bearing, making an U/S bush to suit. Re-assembled with selector marks in line but couldn’t get gears. Re-assembled selector with marks out of line and all is fine. Then there’s the exhaust pipes. If they were 2” longer (and silencers 2” shorter) then the bend would clear the footrest instead of being jammed against it. A bundle of aggro all the way.
I’ve had James ML, BSA A7, Velocette Mac, Triton, Hagon japanese and others. I currently have a BSA B31 hill-climb bike, Weslake speedway engined sprint bike, DOT scrambles with Villiers 6E, dog-ear japanese in a B31 frame, Honda Firestorm, my own 800cc vee-twin in a BSA M21 frame and this A10 GF. Which has been more trouble than all the other bikes. Am currently fitting an own 1,000cc vee-twin in an A10 frame.
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Hi RD,
Glad to hear that you found the problem
Surely 2 pints would be very noticable drop in level in the tank?
Your tale of woe with the state of the bike and the work involved in repairing it just about compares with my own experiences *eek*
Every project I seem to take on has been through the butchers shop *sad2*
, my own 800cc vee-twin in a BSA M21 frame
C'mon, Tell us more and post pictures *????*
John
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I had a similar thing occur with a Vincent that had been sitting for about six months.
I opened the sump drain and very little oil came out.
That bike takes a long time to wet sump but when it does, it leaks oil onto the floor
So with some oil on the floor, none in the sump and the oil tank showing down about 2 litres, I topped the oil tank up.
On starting the bike poured out blue smoke then quickly overfilled the oil tank, making an awful mess.
What must have happened was, I think, the same thing that happened to you.
When the drain plug was first pulled a bit of oil came out then an airlock ( timed breather) prevented further oil from draining, even though there clearly was a lot of oil in the sump.
Sort of like a Jerry can with air vent closed-it can be tipped into the pour position but very little comes out of the spout until the vent is opened and the container gets a gulp of air to replace the escaping fluid.
What I learned is not to be in a rush when draining the sump. And maybe roll the engine over with kickstart so that the timed breather can do its job.
Or better yet, in the case of the Vincent, just fire it up and go for a run now and then. It takes at least two months to wet sump to the point that the sump requires draining.
This A 10 is similar, the wet sumping is not an issue if the bike is ridden every couple of months or so. I was quite surprised at how well it keeps the oil where it ought to be.
Glen
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i ve just come across this one.
was it a test?
was it the magnet on the drain bolt holding the sump ball shut? not sure about the answer.
i was well wide of the mark. i thought it was the oil. and another oil debate.
if the oils too thick it cant be sucked up that tiny pipe hole with a ball bearing in the way?
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I will get to the pub, edboy if you are confused read my reply about the oil on the first page of this topic CHEERS *smile* mine never wet sumps now it has the srm pump and has no problem sucking up straight 50 oil when its cold weather,,, just a bit of a bugger to kick over but I don't do many winter miles so I don't change it *beer*
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another medal lost.
yes i m confused alright. and its getting worse with age.
isnt a sticking ball bearing and wet sumping in the bsa owners rocket science handbook ?
i dont know, what day is it?
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The point is I suspected it might have wet-sumped (as do many bikes) and therefore drained the sump before starting. I was then faced with clouds of smoke and substantail oil loss. My other bikes, if started when wet sumped, only smoke a little - and don't chuck out ANY oil. So what gives here? And why did the oil fail to come out, when clearly there was a pint or two still in the sump despite my original oil drain only producing half a cupful before reducing to a drip? Appears these bikes have a habit of forming a vacuum when trying to drain the sump. Very strange.
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G'day RD.
My A7 wet dreams like a 14 year old but never had that problem. Could the gauze plate be covered in gasket/silicon or anything else used to seal things?
Cheers
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Highly unlikely - have only ever use a smear of grease or blue hylomar to retain gaskets, and then on one side only. Because my bikes get ridden only occasionally, I'm used to draining sumps before riding, which is why I fitted an aftermarket 'sump' on this bike with a drain plug so I didn't have to drop the sump plate every time. My other bikes have a sump plug as standard (eg B31). Can only presume, as any oil in the crankcases has - on this bike - to drain through the gauze, that somehow a partial vacuum prevented flow to the plughole. On the other bikes, the drain plug goes to the crankcase direct, bypassing the gauze.
As stated previously, the fact the bike made so much of a crisis about oil in the crankcases when my other bikes simply carry on with very little smoke if started in such a condition puzzled me. Anyway, now I'm running it regularly as I'm shaking it down from the rebuild, oil situation is fine. No more smoke or oil POURING out and a strong return flow to tank. Just got to sort out the front brake (see other posts) and find out why the LH slider leaks oil - sometimes.
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As old bikes go, the A7 and A10 are not very quirky.
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Pressure relief valve ??
I second this one bsa Bill, had trouble with mine.
TTJohn
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a7 and a10 s are easy to maintain. check the oil returns with the oil cap off when you start up and your ready to go. my old manual says clean the p.r.v. every 1000 miles and use sae 40 in sumer sae 30 in winter. i fit anti drain valves and norton commando cartridge oil filters to all my a10s. the main problem i encounter is blocking petrol tap filters because the fuel is rubbish.