Author Topic: Smoking  (Read 901 times)

Offline Swarfcut

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Re: Smoking
« Reply #15 on: 09.10. 2018 08:37 »
 Just a thought to add to the mix. Have you checked the width of the piston ring grooves with the thickness of the rings? In case I am stating the obvious, as the piston descends, the ring rises to the top of the groove. Piston rising, ring moves to bottom of the groove. Too much gap here means you will have a very effective oil pump transferring oil from the bore to the combustion chamber.  This is one aspect we take for granted with new precision parts....you reckon they are made correctly. But either component is on the wrong side of accepted tolerance you will get problems. As the radial seal of the ring to the bore is reasonably OK, you have pretty good if unbalance compression. There should be the barest minimum of clearance between the sides of the ring groove and the ring. On a worn engine the rings can be worn to a "T" on its side profile , burn oil but still have good compression.  After the frustration and hassle  I would be inclined to nail it back together and get some miles in before the weather turns.

Offline Colsbeeza

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Re: Smoking
« Reply #16 on: 10.11. 2018 08:10 »
Thanks Swarfcut,
I measured the grooves and rings on both pistons. They are both identical and within spec for new gear. So why does one cylinder always blow smoke on startup and the other never has.
I have been away for a few weeks, so didn't do much anything on the bike. But I got into it over the last two days. I checked the breather, fitted a new cork but there wasn't anything wrong with the old one. Checked the breather passage, re-tensioned the head bolts, stripped the oil pump and detailed a few minor issues with it, checked the sump suction tube and ball, etc etc. There is nothing more I can do. And yes the left cylinder smokes exactly as it has been doing for the past 12 months.
I think that leaves me with just putting some miles on it in the hope that the problem will go away. If it is still smoking after 100 miles or so, then the only thing left is pistons.!! I could not see anything wrong with them, but that is all that is left to do.
Cheers
Colin
Colsbeeza
Australia

Online Ted_Flash

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Re: Smoking
« Reply #17 on: 10.11. 2018 09:42 »
Colin,

Have you considered the possibility of a warped head/cylinder joint.  I had a smoking problem and ruled the head/cylinder joint out as I thought cast iron can't bend.  However they certainly had, and a skim sorted the problem.
Ted Wilkinson, Ramsbottom, Lancashire
1950 Golden Flash

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Re: Smoking
« Reply #18 on: 10.11. 2018 09:48 »

 Mine periodically does a bit of that, but stops fairly soon- the other week it did it at the lights, but stopped same...... *dunno*

 only thing I can think of is don't look back ..... *bright idea*
Started building in about 1977/8 a on average '52 A10 -built from bits 'n pieces never resto intended -maybe 'personalised'
Have a '74 850T Moto Guzzi since '92-best thing I ever bought doesn't need a kickstart 'cos it bump starts sooooooooo(mostly) easy
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Online bsa-bill

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Re: Smoking
« Reply #19 on: 10.11. 2018 10:28 »
Quote
Mine periodically does a bit of that, but stops fairly soon-

Mine did too, almost every time it started it would smoke until maybe quarter of a mile then it would clear, then one day  through the winter when I started it and ran it for a while I noticed the smoke did not clear, turned out to be a broken oil ring.
Question is was it broken all the time or just when the smoke would not clear, (edit) well on reflection it does not smoke at all now since the rings were replaced
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 Swarfcut

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Re: Smoking
« Reply #20 on: 10.11. 2018 11:12 »
 Colsbeeza...Reckon you have done more than enough to fix the smoke. It is certainly frustrating when through a combination of unrelated circumstances this is what you get.

   On the other hand it may be the only working example of that pesky li'l 'old oil hole in the drive side rod, doing its job of oiling that left hand bore on cold start until the oil pressure drops as the motor warms and the oil thins out.

  This gives you the bragging rights to demonstrate  it at every suitable moment..  Meanwhile, nail it back together and enjoy riding while you can.  Good chance it will settle down OK with use, as long as it smokes you know you still have some oil in the tank.

   Cheers, Swarfy



Offline berger

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Re: Smoking
« Reply #21 on: 10.11. 2018 11:39 »
I did not go to the pub! first Friday missed in months, anyway I will go today *beer* *countdown* back to some nonsense, colsbeeza at this stage in your fettling I would be inclined to stop the oil reaching the rocker box even though you say it has new bits , I don't know weather yours has cast valve guides or bronze BUT my top end was starved for 80odd miles with bronze guides and no damage done, I personaly would risk a mile or two up the road  . you never know it could tell you a story and help pinpoint the problem, good luck *beer*

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Re: Smoking
« Reply #22 on: 10.11. 2018 17:55 »
Colin - after your earlier post I was going to bet you wouldn't find a broken ring, but I got in too late to make the prediction. Like yourself, I've done many engines over the years, but have to say the A10 never ceases to surprise me. Quirky as hell. BTW, my right cylinder smokes for a few minutes after start up, but clears soon after. About 100 miles since rebuild now and it's improving. My pistons are JP. Looked cheap and in a cheap box (price wasn't) but I guess, as others have said, we should consider ourselves lucky we can at least get parts for our bikes.
'49 B31, '49 M21, '53 DOT, '58 Flash, '00 Firestorm, Weslake sprint bike.

Offline Colsbeeza

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Re: Smoking
« Reply #23 on: 11.11. 2018 11:23 »
Hi Ted Flash,
During my recent head rebuild, I got the guys to reface the gasket surface and I fitted a solid copper head gasket. I have had no indications of a leak, so I think that is OK. Berger, that idea crossed my mind today. I will cut off the rocker oil supply. If that fixes it, I'll know in 2 minutes without riding it. I suspect it won't, as I have the original banjo orifices (orifi?) of 1.14mm (3/64"). The guides are cast iron, so some inherent lubrication should avoid any troubles.
Today, I rode it 42 miles to get it inspected for Club Rego. I rode it down the driveway, and I looked back after 50 metres and a huge pall of white smoke would mean that any cars following would have to creep through it slowly. Thereafter I saw no sign of smoke. The missus said that it was white with a bluish tinge. No sign of oil from breather outlet either. Upon returning, I wiped my finger in the mufflers. The RHS was quite dry, but the LHS was oily and black with carbon (very dense like carbon-black) but the oiliness was quite thin, like the oil had been diluted with fuel. Any chance that I have a pinhole between the float chamber (LHS) and the inlet duct.?? Any fuel leakage would favour the LHS cylinder. Grasping at straws now I know and the smoke would not be white!! The left exhaust is showing a blue tinge, whereas the RHS is a light straw, so maybe a bit advanced on the LHS.
It ran well above 1/4 throttle, but the pilot circuit needs some tuning - a bit of spitting when hot.
The old rings were not broken but have been replaced with Hepolite rings purchased from SRM, so definitely not a broken ring.
Dutch for the next few rides I'll take your advice and not look back. Swarfcut, I'll forgo the bragging rights if I can stop the smoke.
Colin
Colsbeeza
Australia

Offline mugwump

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Re: Smoking
« Reply #24 on: 11.11. 2018 14:04 »
The moistness in the lefthand silencer is probably condensation, are both cylinders getting equally as hot during the first few minutes of running from cold. Can I suggest that the lefthand cylinder is not firing cleanly, for some reason.

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Re: Smoking
« Reply #25 on: 11.11. 2018 20:52 »
Hi Col,
Although I have not come across a problem like this on BSA's , I once worked on a Tri**ph that smoked like a bastard
no matter how many pistons/ sets of rings I fitted to it *problem*
Eventually I spoke to an "old hand" about it, his answer went like this.....
"All them fkn cylinders go porus once they get the first rebore"
I found a new cylinder for it and fitting that cured the problem

Something else to try before ripping it all apart again
Try draining the sump before the next start up  *????*
If there is no (less) smoke after starting, the problem maybe oil draining into the crankcase
If there is excess oil in the sump this may point you towards a solution  *????*

It takes quite a long time/trip to burn off all the oil  that has stuck to the inside of the exhaust and silencer

John
1961 Super Rocket
1963 RGS (ongoing)

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Re: Smoking
« Reply #26 on: 12.11. 2018 07:24 »
G'day Col.
I agree with John. The sump will hold about a cup full (250ml) after a run. Drain it, there will be enough in the cam trough to lube at start up. The pump will/should supply oil to the crank straight away so no fear there.
See if that makes a difference.
Cheers
.
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Online Bsareg

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Re: Smoking
« Reply #27 on: 12.11. 2018 11:01 »
Years ago my 1960 mini engine became a real smoker so dropped in an exchange engine only to find it smoked worse than the original. I had a go at the supplier who assured me there was nothing wrong with the engine but to try it for a week. Sure enough the more efficient engine eventually cleared out the oil soaked exhaust and the smoke cleared. Its still going well........
C11,B40,B44 Victor,A10,RGS,M21,Rocket3,REBSA

Offline Colsbeeza

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Re: Smoking
« Reply #28 on: 16.11. 2018 05:03 »
Hi Mugwump,
  I don't think it could be moisture condensation, and both cylinders seem to warm up equally. She seems to have heaps of power, and I have tried new plugs (recommended Champion L82C ). This has been going on since first startup in 2015. Why moisture would favour one cylinder so extremely is beyond me. Thanks for suggesting it so will have to think further about that. John CL, I have drained and measured the sump many times, usually get about 150 mls even after several weeks, so I am happy it is not wet-sumping (surprising since I didn't know to check the crankcase non-return ball when I had it apart). I still drain the sump each time to make bl-- sure it is not the source of smoke. I have never got 250 mls as Muskrat has experienced. I haven't started it since my run last Sunday, so will be hoping the pipes don't hold much oil, although the LHS tail pipe was still wet with a black carbony oiliness when I got home. I am homing in on a basic flaw in the Left side piston, but your experience with the Triumphs is interesting. I honed both bores recently, and there does not appear to be any obvious pores, but if they are there, then probably too small to be visible. Given the amount of smoke, I think I would be looking for a fairly visible problem.?? It might be a good idea to find a set of cylinders in case I have to pull it apart again.
The bike has done about 85 miles on the reconditioned engine, so maybe I should not panic just yet.
 Think I'll retire to the shed and give it a kick in the guts and see how it smokes. I'll get a few photos.
Cheers Col
Colsbeeza
Australia

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Re: Smoking
« Reply #29 on: 16.11. 2018 16:50 »
Hi Col,
There was nothing visible in/on the Triumph bore
A dye penetrant test might show up porosity? or maybe just heat the cylinder up after degreasing it and see does oil appear on the bore surface  *????*

If you start it with the sump drained and it still smokes,
I would remove the offending side exhaust pipe, shine a light into the port and look for evidence of oil
Maybe there's a score in the head in the guide bore and oil is weeping down there  *????*
(I have found that too *sad2*)
Look for the same on the inlet side, but this might show up as an oily plug??

It might be worth starting the bike with the oily side exhaust removed  *????* to see if there's "fresh" oil/smoke
coming from the engine *????*

John
1961 Super Rocket
1963 RGS (ongoing)