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1970 BSA A50 New motor smoking from one cylinder #458076
10/09/12 10:01 pm
10/09/12 10:01 pm
Joined: Jun 2012
Posts: 33
Seattle, Washington
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RStn7 Offline OP
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Seattle, Washington
After a lot of tinkering with clutch and electrical issues I finally got the bike ready. It started on the second kick - great feeling but even after riding it for about an hour or so total time (mainly test rides to adjust one thing or another) it is still smoking bad from the left cylinder.

There is oil dripping out of the exhaust pipe on that side.

Back story: New + 0.020 pistons and rings installed on a fresh bore. New valves, springs and guides. Resurfaced head. New shell bearings on resurfaced crankshaft. I adjusted the valve clearances twice before starting the motor.

I measured the compression and to my surprise I got higher readings on the "bad" cylinder. Appx 140 psi/six kicks (L), and 120 psi on the other cylinder. Does that mean the rings are good? Then, where is the oil coming from?

At the suggestion of my mechanic I'm using heavy duty diesel motor oil 15W 40 to break in the motor. When I pulled the spark plugs the one on the "bad" cylinder had a lot of carbon. The other one had some but not as much.

Again, the motor has been running for about one to two hours total.

Any ideas or suggestions would be very much appreciated.


Adrian
"If it's not broken, I don't want it."
1970 BSA A50 R
1960 Matchless G2CS
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Re: 1970 BSA A50 New motor smoking from one cylinder [Re: RStn7] #458077
10/09/12 10:06 pm
10/09/12 10:06 pm
Joined: Aug 2001
Posts: 2,610
Springfield Nebraska
Richrd Offline
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Springfield Nebraska
Broken ring? one or more rings upside down?


Rich (member ThreeMustGetBeers)
"It's not always about going fast. Sometimes it's nice to slow down" (Wendy E.2016)

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Re: 1970 BSA A50 New motor smoking from one cylinder [Re: RStn7] #458079
10/09/12 10:08 pm
10/09/12 10:08 pm
Joined: Aug 2001
Posts: 1,799
Christchurch, NZ
Kevin (NZ). Offline
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Christchurch, NZ
How long has the engine been sitting around with oil in it ?

It sounds like it may just be a simple case of wet sumping.
Did you drain the sump before starting the engine ?

It may be a very easy fix..


Why, Y, Dash Y..



Re: 1970 BSA A50 New motor smoking from one cylinder [Re: RStn7] #458080
10/09/12 10:11 pm
10/09/12 10:11 pm
Joined: Jul 2007
Posts: 529
Wollaston Northants
kelvin Offline
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Wollaston Northants
You will have to remove the cylinders to make sure you have not broke a ring. Do not use modern multigrade oils. get some classic straight 40w or 50w

Re: 1970 BSA A50 New motor smoking from one cylinder [Re: kelvin] #458119
10/10/12 4:15 am
10/10/12 4:15 am
Joined: Oct 2008
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Gnashville
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Gnashville
Originally Posted By: kelvin
get some classic straight 40w or 50w

The cheaper, the better. Use this only to seat the rings, then put in the good stuff.
BTW: Was the top end assembled dry?


Stepping on others doesn't make you stand tall.

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Re: 1970 BSA A50 New motor smoking from one cylinder [Re: RStn7] #458125
10/10/12 5:56 am
10/10/12 5:56 am
Joined: Jul 2009
Posts: 3,549
Vic. Australia
P
Pete R - R.I.P. Offline
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Vic. Australia
I'd suspect the new guides,before I suspect a ring problem.
Possible leakage between the guide and the head.Does it smoke more about a minute or two after start-up,but not immediately when you start it cold?

If yes,try sealant around the guides,under the lower spring collar.

Re: 1970 BSA A50 New motor smoking from one cylinder [Re: Pete R - R.I.P.] #458453
10/12/12 6:40 am
10/12/12 6:40 am
Joined: Jun 2012
Posts: 33
Seattle, Washington
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RStn7 Offline OP
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Seattle, Washington
You might be right. There's hardly any smoke when I start it and there's an equal amount of smoke on both cylinders, but after it runs for few minutes one starts smoking bad and I even get oil leaking through the exhaust.

Going to pull the heads cover off tmrw and have a look. What kind of sealant do you recomend?

Thanks,

Adrian


Adrian
"If it's not broken, I don't want it."
1970 BSA A50 R
1960 Matchless G2CS
Re: 1970 BSA A50 New motor smoking from one cylinder [Re: Richrd] #458456
10/12/12 7:13 am
10/12/12 7:13 am
Joined: Jun 2012
Posts: 33
Seattle, Washington
R
RStn7 Offline OP
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Posts: 33
Seattle, Washington
I hope it doesn't have a broken oil ring. As for upside down rings it's hard to say. I looked at the rings that came with the new pistons and there were no markings on them as to which way was up.

Just got another set of rings, UK made or so they were advertised, and they don't have any markings on them either.

How can you tell if they have a direction?

Thanks,

Adrian


Adrian
"If it's not broken, I don't want it."
1970 BSA A50 R
1960 Matchless G2CS
Re: 1970 BSA A50 New motor smoking from one cylinder [Re: RStn7] #458473
10/12/12 10:37 am
10/12/12 10:37 am
Joined: Jul 2009
Posts: 3,549
Vic. Australia
P
Pete R - R.I.P. Offline
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Joined: Jul 2009
Posts: 3,549
Vic. Australia
Originally Posted By: RStn7
,but after it runs for few minutes one starts smoking bad and I even get oil leaking through the exhaust.

It sounds like guide leakage;it could be either the intake or exhaust,or even both.
I first clean it up with brake cleaner or Loctite primer.After that dries up,soak some Loctite 290 Wick-In around the guide.Some might seep in and seal the score mark.Clean up the excess after it sets.I then use Loctite 567 teflon thread sealant around the guide under the lower spring collar.The 567 isn't meant for this,but it's good.It would seal anything anytime,and doesn't set rock-hard.

Some people just use a good silicone sealant around the guide.No reason why it shouldn't work.

If you sharpen the top of the guides like a pencil at about 120 degree included angle,it will reduce oil consumption down the guides.Any chamfer in the top of the guide bore will increase oil consumption.

Re: 1970 BSA A50 New motor smoking from one cylinder [Re: Pete R - R.I.P.] #461559
11/02/12 2:59 am
11/02/12 2:59 am
Joined: Jun 2012
Posts: 33
Seattle, Washington
R
RStn7 Offline OP
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Seattle, Washington
Pete,

I think you were right about the oil leaking around the guide. First of all I'm sorry it took so long to get back here but didn't have a lot of time to work on the old bike and we had a few weeks of constant rain in the Pacific Northwest. I took the engine top end off and this is what I found.

First, I adjusted the valve (tapet) clearance too tight .006 for intake and .008 for exhaust even though I remember checking it twice.

Then there were some slight abrasive particles (in the oil) I found on the rocker arms shaft. Especially on the exhaust shaft.

The exhaust valve on the cylinder that was smoking (and leaking oil) was pretty burned in the chamber and had significant carbon deposits on the guide and stem. I took the heads to a machine shop I've used (diferent than the one that did the job last time) and they said the it needs to be redone.

No broken or upside rings but ...I did find a lot of small scratches on the top of the piston's walls, right above the compression ring, that looked very strange. The cylinders are smooth and don't have a lip or anything that could make those scratches.


Adrian
"If it's not broken, I don't want it."
1970 BSA A50 R
1960 Matchless G2CS
Re: 1970 BSA A50 New motor smoking from one cylinder [Re: ] #461562
11/02/12 3:22 am
11/02/12 3:22 am
Joined: Jun 2012
Posts: 33
Seattle, Washington
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RStn7 Offline OP
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Seattle, Washington
Hello Allan,

I just got another set of piston rings that a supplier in California says they are made in England and these rings have no markings on them either. More than that I looked at the end of the compression rings for quite some time with a magnifying glass and they look square. There is no taper or camfer or sloping. The oil control ring (one piece) has taper on both upper and lower rings.

Have you seen or heard of any rings made in England that have no markings and no orientation or do you think these are Taiwan junk. The brand on the box is MCA - Aston Ltd from Birmingham.

I finally found some time to get the engine apart and this is what I found.

First, I adjusted the valve (tapet) clearance too tight .006 for intake and .008 for exhaust even though I remember checking it twice.

Then there were some slight abrasive particles (in the oil) I found on the rocker arms exhaust shaft.

The exhaust valve on the cylinder that was smoking (and leaking oil) had a pretty burned face in the chamber and significant carbon deposits on the guide and stem. I took the heads to a machine shop I've used in the past(diferent than the one that did the job originally) and they said the it needs to be redone.

No broken or upside rings but ...I did find a lot of small scratches on the top of the piston's walls, right above the compression ring, that looked very strange. The cylinders are smooth and don't have a lip or anything that could make those scratches.


Adrian
"If it's not broken, I don't want it."
1970 BSA A50 R
1960 Matchless G2CS
Re: 1970 BSA A50 New motor smoking from one cylinder [Re: RStn7] #461563
11/02/12 3:24 am
11/02/12 3:24 am
Joined: Sep 2002
Posts: 7,813
Seattle
Alex Offline

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Alex  Offline

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Seattle
Look at the oil rings. Are the lands where they are supposed to touch the cylinder uniformly shiny? I has some total crap rings supplied with one set of A50 pistons where you could see that the oil rings had only touched in three places around the bore. Same symptoms as yours.

Cheers


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Re: 1970 BSA A50 New motor smoking from one cylinder [Re: RStn7] #461595
11/02/12 2:18 pm
11/02/12 2:18 pm
Joined: Sep 2004
Posts: 836
Farnham, Surrey, UK
gunner Online content
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gunner  Online Content
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Farnham, Surrey, UK
The rings as supplied with GPM/JP pistons aren't much good IMHO.

I would try using a new set of rings which use a three piece oil control system. These are much better at controlling oil consumption than one piece rings.

Some manufacturers can supply suitable rings directly from their catalog if you supply the bore dimension and ring thickness, or can even make bespoke rings, see:-

Total Seal Rings
Hastings Rings
Cords Piston Rings



-


1968 A65 Firebird
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Re: 1970 BSA A50 New motor smoking from one cylinder [Re: RStn7] #461653
11/02/12 10:22 pm
11/02/12 10:22 pm
Joined: Feb 2010
Posts: 451
Au
M
markoz Offline
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Posts: 451
Au
There are many different profiles for piston rings. The new ones you have are rectangular profile, that does not mean that they are cheap Taiwan made. Some ring set ups are square top ring, tapered middle ring. I guess everyone has a preference/point of view on these.
Cheers mark.

Re: 1970 BSA A50 New motor smoking from one cylinder [Re: Alex] #461750
11/03/12 7:39 pm
11/03/12 7:39 pm
Joined: Jul 2001
Posts: 12,936
Central Virginia
Lannis Offline

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Lannis  Offline

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Central Virginia
Originally Posted By: Alex
Look at the oil rings. Are the lands where they are supposed to touch the cylinder uniformly shiny? I has some total crap rings supplied with one set of A50 pistons where you could see that the oil rings had only touched in three places around the bore. Same symptoms as yours.

Cheers


What a shame that people sell that sort of stuff to us ... you'd think there would be better ways to make money dishonestly than going to the trouble of selling crap piston rings ... ?

Lannis


I stopped believing for a little while this morning. Journey is really going to be upset.
Re: 1970 BSA A50 New motor smoking from one cylinder [Re: RStn7] #461861
11/04/12 3:15 pm
11/04/12 3:15 pm
Joined: Mar 2005
Posts: 10,205
Boston, Massachusetts
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John Healy Offline
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John Healy  Offline
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Posts: 10,205
Boston, Massachusetts
Quote:
When I removed my GPM pistons after 1000 miles the rings were badly bured ( cuts my hands to shreds ) and the ring faces were badly scored almost like ridges as though they weren't bedding in, which they weren't!


Some thoughts:
Although I can't comment on Alan's experience this sort of problem is typically caused by hard honing stone chips left embedded in the bore after the final honing of the cylinder. It is not the rings. It is the person who cleaned the cylinder before assembly.

Taper faced rings can be sorted by standing the ring on its edge and noting how it stands. The standing ring will reflect the angle of the face. There are also other features that should be noted as to how the rings should be installed on the piston. Refer to the ring makers information as similar features can be used in different ways. For example a lot of ring makers "step" the face of the middle compression ring. Some face the step at the top, and more typical of motorcycle manufactures, place the step at the bottom. Be careful of what your local automotive machine shop recommends - refer to the manufacturers first!

These engines were never manufactured in such a way as to allow them to be used with anything other than 20/50, or straight weight 30 or 40 depending upon the ambient temperature - (yes there are rare occasions where the temperature is above 100F o below 32F where one would use different oil). Refer to the manufacturers recommendations and use the weight oil they recommend. They weren't stupid!

API-SG has been brought back from the dead... While once considered an expensive boutique oil offered by the likes of Redline, Spectro, etc., you will now find nearly all oil companies offer it. it is Motorcycle oil with the JASO-MA (MA2) rating and is designed for engines where the clutch (and where applicable the transmission) shares oil with the engine (1970 and later Triumph twins). There is some evidence that it could be considered for initial assembly and break-in. It is pre "energy conserving" oils introduced in 1994 with API-SH. It has no energy conserving friction modifiers and more ZDDP.

As far as finding rings with several prominent contact/wear points experts typically trace this to the person installing the rings. Grey cast iron rings bend easily. In the effort to "spring the ring" over the piston during installation rings are pulled to far, or unevenly and bending results. Hepolite installed the rings at the factory and insisted that they not be removed by the person installing the piston. This is not the fault of the ring, or its manufacturer. It has been my experience is it is rarely the rings that caused the problem!

Just my opinions


Re: 1970 BSA A50 New motor smoking from one cylinder [Re: RStn7] #462362
11/08/12 1:05 am
11/08/12 1:05 am
Joined: Jun 2012
Posts: 33
Seattle, Washington
R
RStn7 Offline OP
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Seattle, Washington
This is my first project and also a learning opportunity ...some lessons a bit more expensive than others. In the end the sweet sound of the engine and the way this little bike rides makes up for all the trouble and headaches.

I got the heads back from the machine shop after a new valve job - apparently the first time it was done with new valves, guides, seats, springs, by a different shop, it wasn't right and it was leaking around the guide on the exhaust valve in the left cylinder.

When I looked at the rings (new along with new 20 over pistons) that I put in I realized I made few mistakes. The compression rings are totally square and there is no taper on the face whatsoever and that led me to bellieve that there was no orientation. But the oil control rings, upon closer examination, do have taper of the outer edges. One of them was upside down and the end gap on the other oil control ring was too big.

New rings in, heads on and I hope that by tomorrow to finish geting everything together for a short test ride. Right now I have 20/40 diesel engine oil in it I was going to keep to help with the breaking in. Any suggestions on how many miles? And if I won't be able to get that done before spring, should I change to a different oil for storage?


Adrian
"If it's not broken, I don't want it."
1970 BSA A50 R
1960 Matchless G2CS
Re: 1970 BSA A50 New motor smoking from one cylinder [Re: RStn7] #462396
11/08/12 11:25 am
11/08/12 11:25 am
Joined: Aug 2001
Posts: 4,081
argyll. scotland, uk
gavin eisler Offline
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argyll. scotland, uk
Its not just the water in the oil that does damage but other acid products caused by combustion/ burning. The water disappears as soon as the motor heats up exiting as vapour from the breather from the oil tank..


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Re: 1970 BSA A50 New motor smoking from one cylinder [Re: RStn7] #462501
11/09/12 6:51 am
11/09/12 6:51 am
Joined: Sep 2002
Posts: 7,813
Seattle
Alex Offline

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Seattle
FWIW I have never seen oil ring that have an orientation. I would be suspicious of such a thing.


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'67 Royal Star
'71 Rickman Metisse
'40 Silver Star
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Re: 1970 BSA A50 New motor smoking from one cylinder [Re: RStn7] #462536
11/09/12 1:14 pm
11/09/12 1:14 pm
Joined: Mar 2011
Posts: 836
derby england
wak Offline
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derby england
i think i would be more concerned about abrasive in the oil ?if it got around the engine cheap piston rings will be the least of your worries, have you had any parts blasted?


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Re: 1970 BSA A50 New motor smoking from one cylinder [Re: RStn7] #462540
11/09/12 1:51 pm
11/09/12 1:51 pm
Joined: Mar 2005
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Boston, Massachusetts
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John Healy Offline
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Boston, Massachusetts
Oil refined as an lubricant isn't by itself that good an anti-oxidant. To increase the engine oil's ability to prevent rusting during the refining process anti-oxidants are added. With time, oil enhanced with anti-oxidants, can be overwhelmed by the shear volume of water and wIth time and use the the anti-oxidants oil become less effective.

This is why most oil manufacturers recommended that you change the oil before storage.

Storage comes at a time of the year when trips are typically shorter. Shorter trips mean the engine doesn't get hot enough, or run long enough to naturally condense the water into vapor that then exits the engine through the breather. Draining the oil before storage time flushes all of the water collected from those short runs and gives the engine a fresh charge of anti-oxidants.

One key to storage is avoiding rapid changes in temperature. Things to avoid are storing a bike in a heated garage where the door is opened twice a day, next to a south facing window in an unheated garage, or next to the furnace in the cellar (basement). You are looking for a place that is as dry as possible, where the temperature changes little, and if it changes, that it takes place slowly.

Am I making any sense?
John Healy



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