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Well, I set the timing, and then reset the timing, and then re reset the timing, and then as I was kneeling down next to the motor applying some throttle to see if the carburetor was andjusted, as it was still running poorly, I noticed there was smoke coming out from between the head and the barrel, so now I think I've got a blown head gasket, & I need to fix that before I will probably have to retime it yet again. At this point, I'm seriously getting fed up with this bike. It was sold to me as running and drivable from someone who seemed knowledgable and reputable and is even a member on this forum, but I've found nothing but serious problems with it. Every time I fix one thing, I find two other things wrong and without stripping it completely down and starting from scratch, I doubt that I'll ever get it running well enough to ride. Frankly, I didn't pay what I did for a total rebuild. Sorry for venting my frustrations here, but I've invested months and a lot of money and feel like I'm getting no where.

Last edited by SpencerAZ; 01/21/16 8:40 pm.

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After checking my spares catalogue, it doesn't show a head gasket for the B33. Is that really the case? If so, why is smoke and fluid being spat it from the joint? Yes, fluid. Hard to tell if it's fuel or oil, or probably both, but the fin at the joint is wet, and there's spatter on the head pipe.

Is it possible that this is the source of my problems? I'm still getting sharp popping ignition and combinations of black and grey smoke.

Last edited by SpencerAZ; 01/21/16 8:37 pm. Reason: grammar correction and additional information

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Spencer,
you are having a bad run with this bike but anyway I will try to help, this is long winded but read on as I feel some advice you have been given is not correct but you have also been given good advice too.

Be very careful setting the ignition timeing. Make absolutely sure you know what way you advance or retard the timing with the cable as from reading the previous posts you have been told correctly and incorrectly or else I have read it wrong. On your magneto the cable enters the battery side of the end housing, that means you have to pull the cable (which you have been told) to advance the timing, end of story. It does not matter what way you push or pull the handle bar lever, as long as you tighten the cable by either pushing the lever or pulling the lever you will advance the ignition timing. People get mixed up in this because they fit levers from the right hand side to the left hand side of the handle bars. You have to know if its cable tight advance or cable slack advance and lever toward you advance or lever away from you advance.

Another thing, setting the main needle clip in the bottem hole produces a richer setting, not a leaner one. Think about it, you are raising the needle and letting more fuel out for the same throttle setting. If you think any engine is running rich, turn the fuel tap off while it is running and watch closely what happens, does it start to run better or run worse, that will tell you for sure if its rich or lean.
Watching your bike run on your video it looks like the timeing is maybe retarded but its not actually running that bad, that could explain the smoke you seen coming from the engine because it will start to run hotter like that, these bikes leak oil from nearly every joint, a bit of oil on the fins under the cylinder head will soon start to smoke, 5 or 6 seconds of retarded ignition and a couple of revs on my bike produces a wisp of smoke from the engine and exhaust pipe, you would think the engine is pulling a load up a hill as it does not want to rev with the ignition retarded.

Now, here is how I ignition time my B31, its not 100% accurate but it gets the engine running very very close to correct. Set the advance / retard lever and cable to the full advance position. Kick the bike over slowly until you feel the compression stroke. Remove the spark plug. Bring the piston up slowly to the top so you can see it and set it at T.D.C (top dead centre) taking into account there is a dead spot in the crank at the point where the crank rotates but the piston doesn't move, you have to feel for it. Get a vernier caliper and measure the distance from the edge of the spark plug hole to the piston and whatever it is in Millimetres, add on 13 millimetres. I know the vernier will be pointing at a bit of an angle at the piston but is accurate enough for now. Now rock the engine back and take the piston back down and place a piece of thin cigarette paper between the points, rock the engine forward again and bring the piston up slowly until the piston is the distance you measured plus the 13 mm from T.D.C. That means your piston is now 13 mm from T.D.C. At that point your points should just be starting to open which you can confirm if the paper has been released from between the points. If not you can move the points slightly or if it is completely wrong you will have to remove the right hand side engine timing cover and remove the magneto drive pulley from the taper on the magneto shaft with the special puller that threads into the gear wheel.

You will know when you have the ignition timing set right if you have the ignition timing fully advanced with the lever and you kick the bike over compression after priming it without actually trying to start it and the engine kicks back at you, retarding the ignition with the lever will soon show you where it doesn't kick back and that is the sweet spot where my bike starts first kick every time. Retarding it further produces a engine which is impossible to get to fire never name start.

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Originally Posted by B31 Ally
Spencer,
you are having a bad run with this bike but anyway I will try to help, this is long winded but read on as I feel some advice you have been given is not correct but you have also been given good advice too.

Be very careful setting the ignition timeing. Make absolutely sure you know what way you advance or retard the timing with the cable as from reading the previous posts you have been told correctly and incorrectly or else I have read it wrong. On your magneto the cable enters the battery side of the end housing, that means you have to pull the cable (which you have been told) to advance the timing, end of story. It does not matter what way you push or pull the handle bar lever, as long as you tighten the cable by either pushing the lever or pulling the lever you will advance the ignition timing. People get mixed up in this because they fit levers from the right hand side to the left hand side of the handle bars. You have to know if its cable tight advance or cable slack advance and lever toward you advance or lever away from you advance.

Another thing, setting the main needle clip in the bottem hole produces a richer setting, not a leaner one. Think about it, you are raising the needle and letting more fuel out for the same throttle setting. If you think any engine is running rich, turn the fuel tap off while it is running and watch closely what happens, does it start to run better or run worse, that will tell you for sure if its rich or lean.
Watching your bike run on your video it looks like the timeing is maybe retarded but its not actually running that bad, that could explain the smoke you seen coming from the engine because it will start to run hotter like that, these bikes leak oil from nearly every joint, a bit of oil on the fins under the cylinder head will soon start to smoke, 5 or 6 seconds of retarded ignition and a couple of revs on my bike produces a wisp of smoke from the engine and exhaust pipe, you would think the engine is pulling a load up a hill as it does not want to rev with the ignition retarded.

Now, here is how I ignition time my B31, its not 100% accurate but it gets the engine running very very close to correct. Set the advance / retard lever and cable to the full advance position. Kick the bike over slowly until you feel the compression stroke. Remove the spark plug. Bring the piston up slowly to the top so you can see it and set it at T.D.C (top dead centre) taking into account there is a dead spot in the crank at the point where the crank rotates but the piston doesn't move, you have to feel for it. Get a vernier caliper and measure the distance from the edge of the spark plug hole to the piston and whatever it is in Millimetres, add on 13 millimetres. I know the vernier will be pointing at a bit of an angle at the piston but is accurate enough for now. Now rock the engine back and take the piston back down and place a piece of thin cigarette paper between the points, rock the engine forward again and bring the piston up slowly until the piston is the distance you measured plus the 13 mm from T.D.C. That means your piston is now 13 mm from T.D.C. At that point your points should just be starting to open which you can confirm if the paper has been released from between the points. If not you can move the points slightly or if it is completely wrong you will have to remove the right hand side engine timing cover and remove the magneto drive pulley from the taper on the magneto shaft with the special puller that threads into the gear wheel.

You will know when you have the ignition timing set right if you have the ignition timing fully advanced with the lever and you kick the bike over compression after priming it without actually trying to start it and the engine kicks back at you, retarding the ignition with the lever will soon show you where it doesn't kick back and that is the sweet spot where my bike starts first kick every time. Retarding it further produces a engine which is impossible to get to fire never name start.


You clarified some of my confusion. On the magneto, I've been timing it with the cable slack for advance, assuming that tightening it was retarding the timing. If I tighten the cable fully, having timed it as such, the kickstarter kicks back on me when trying to find TDC (on compression stroke, I think, but only one time), but kicks over relatively easily with the cable about midway to fully slack. From the sound of it, I've timed it backwards and should time it instead with the cable tightened fully for advance.

The smoke from the head I'm certain is from a leak and not burn off. At idle there is no smoke, but application of the throttle creates a sudden, but slight puff. Also, there is an oily, black residue being spattered onto the exhaust down pipe directly across from where the head and barrel meet. However, if I've timed it poorly, and since there is no gasket, then perhaps this is just a symptom of my error.

I also understand that raising the needle, selecting a lower notch, enriches the mixture. The confusion there probably lies with me not being clear enough in my description, but I appreciate the clarification. Currently, the needle is set on the second notch from the top with a 106 needle jet, 210 main, and 25 pilot. The pilot screw is two turns out from being fully seated. This was suggested for use with an air filter. Today, I was able to get the motor idling without constant throttle, but needed to back the pilot screw out almost completely. However again I think this was probably due more to my error in setting the timing.

If it's helpful to know, the spark plug was black, sooty, dry at the electrode, but wet around the threads. When I first purchased the bike, the plug would be soaking wet, and between running the motor I had to burn off the fuel with a lighter or outright replace it between tests.

For setting the timing, other than having the advance set wrong, I think I've done everything else correctly:

I set the points when fully open to between .010 and .012. I put a .002 feeler in the point where it closes at about 7 o'clock, and rotate clockwise, pulling slightly on the feeler until it slips free at roughly 11 o'clock. I use a socket wrench to turn the motor forward and with the tappet cover removed, find the compression stroke. I turn the motor back to the beginning of the stroke and put a square wooden dowel in the plug hole, perfectly upright, and rotate the engine forward until I feel the point where the piston is at TDC, but not yet turned into the power stroke. I then put a pen knife flat on the head and press a mark into it, remove it, measure a point 7/16 above it, mark that with the knife, rotate the engine back to the beginning of the compression stroke, and forward until the notch in the wood meets the edge of my knife. I then put the mag pinion onto the shaft and tap it home with a socket and a mallet, and tighten the nut back on the shaft with slow even pressure until the gear train shows signs of movement, check my settings again and button everything up.

If I'm missing a step, please point it out to me. I'm going to try my hand at this again tomorrow morning.

Last edited by SpencerAZ; 01/22/16 3:04 am.

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I made a boo boo with the previous posting which I have modified.

You have a pull for advance ( slack retarded ) so you should be setting the timing with the table tight


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Well, I retimed the engine with cable tight for full advance and it's running with a more even sound, but still putting out a lot of smoke and loud, thudding ignition. Also, where the head and barrel meet, I can see bubbles forming, so there's definitely a leak which I'm not sure how to correct. I'm uploading a video of the bike running and I'll put the link here when it finishes.

Addendum:

Video link: https://youtu.be/qeZJByaO5g0

Second video with head removed: https://youtu.be/12VmgMHYL0I

Last edited by SpencerAZ; 01/22/16 4:59 pm.

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Spencer,
I read how you are timing your engine and you have it done 100% as good as you can do it. You understand it better than I thought, especially measuring the distance from T.D.C with the dowel rod and using a pen knife to mark the wood for measurement.

After listing what you say about the wisp of smoke from the joint between the head and barrel it is possible you have a leak there, its also possible the four head bolts are not tightened enough, they are not tightened squarely or they could be seized where they are meant to turn so they wont pull the head down tight enough. Its a daft system where you have to tighten the head down to hold the barrel on at the same time with an open ended spanner. In saying that it works actually quite well with no cylinder head gasket.

If you can see something being spattered onto the exhaust in line with the head jiont then it most likely is coming from the head joint. Also the black sooty plug indicates running rich as well as the four stroking sound or it sometimes is as bad as 8 stroking. Wet spark plug threads in my experience is a sign of excessive oil in the combustion chamber from either cylinder bore or valve stems. I did notice you can kick it over relatively easy, on all my B31's I can actually stand on the kick starter and practically jump on it before it will go over compression, I use the decompressor lever all the time to get the engine to where I want it for starting. You can see the oil smoke from the exhaust when its running.
Did you try turning the petrol tap off an running the bike until it stops and see what it does? In your video its sounding more like what a British single should sound like but its still running rich.

Lastly this is for BSA_WM20,it takes an honest man to admit he made a boo boo, even a slight one, I take my hat off to you as there are very few honest men left in this world.

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I added a second video just now. I removed the head from the motor to inspect the cylinder piston and valves hopefully that will help shed some light on the situation. I also think that at this point as far as the rich mixture issue is concerned I'm better off just purchasing a brand new carburetor outright and eliminating any fault in the carburetor as a possibility.


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Also I just noticed upon inspection of the cylinder head that the intake valve is larger than the exhaust valve which seems backwards but neither of them are marked.

Correction the exhaust valve is marked g2 with ex on the opposing side

Last edited by SpencerAZ; 01/22/16 5:23 pm.

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Intake valves are generally equal to or larger than exhaust vales in most engines.

The reasons are the intake charge is more dense than the exhaust charge, therefore taking up more physical space, and the exhaust charge is under pressure so that helps it evacuate the cylinder vs the intake charge being under vacuum to get into the cylinder.

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While the head is off, block off the spark plug hole and fill it with fuel.
If the valves are making a good seal the fuel should not leak out.

A shot of the top of the piston would be good.

The bolting system is called through bolting and was considered superiour at the time and is a good argueing topic at the pub ( bar to some ).
Please get some gaskets and replace all the goo, yuck.
The only good thing is, it tells that the last person who put it together was a moron mechanic with little idea of old BSA singles, or just plane bone lazy.
The BSA spannar for those through bolts is wider than an normal open ender and there is a flare nut spanner that will fit.


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Originally Posted by Zombie
Intake valves are generally equal to or larger than exhaust vales in most engines.

The reasons are the intake charge is more dense than the exhaust charge, therefore taking up more physical space, and the exhaust charge is under pressure so that helps it evacuate the cylinder vs the intake charge being under vacuum to get into the cylinder.


More dense means the same mass takes up less volume.


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Hi,
B31 has covered most of the issues, and like him I think that your engine is very easy to kick over !!
So poor valve seating, poor bore sealing and or a bad head joint??

The method of sealing the head to the cylinder goes like this,,
providing that theres no damage or distortion to the inner and outer joint faces

Remove head and cylinder, clean joint faces as much as possible
Put a little fine grinding paste around the inner joint face (spigot) and some coarse on the outer face,
rotate the head and cylinder against eash other back and forward
(same as lapping in a valve)
wipe off and replace the paste often until the faces show an even surface all round
The coarse paste will remove a minute amount more than the fine
The inner faces provide the seal, and the minute gap allows the clamping force to be applied to the inner

HTH
John

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I think lazy is probably right. Or they just wanted to slap it together quickly. I think they also had an aversion to oil leaks, but why they thought a 60 year old BSA shouldn't leak is beyond me.

I'll try that trick with the petrol tomorrow morning.

I'll also get a shot of the piston put up. It was remarkably clean, despite the fluid in the exhaust valve recess. The valves had much more carbon buildup.


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Originally Posted by triton thrasher
Originally Posted by Zombie
Intake valves are generally equal to or larger than exhaust vales in most engines.

The reasons are the intake charge is more dense than the exhaust charge, therefore taking up more physical space, and the exhaust charge is under pressure so that helps it evacuate the cylinder vs the intake charge being under vacuum to get into the cylinder.


More dense means the same mass takes up less volume.



Well then...
Water/steam.
Water is more dense, and the steam from that water does indeed take up more space.

You are correct.

However to move them both the same amount of space in the same amount of time using the same amount of force, the water needs a larger opening to move thru.

Irregardless of the form of the matter, the mass is the same. So I guess it comes down to drag coefficients??

It's easier (I guess) to say that intake valves are supposed to be more bigger.

I forgot to take my vitamins today.

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Spencer , your motor is clapped, when you were sold a running motor , the seller left out the fact that BSAs will keep running past the point of normal death, one of the great but inconvenient things about them.

Given the extreme richness, leaking head joint and such you have a couple of options. You are 1 minute away from pulling the barrel, do it , with feeler gauges measure the piston skirt clearance at north South east and West, at the lower unworn section and at the top just below the ring travel lip. Wear will be obvious if you can get more feelers in the top than the bottom by 3 thou or so its done.
Check the rings are there in one piece and installed correctly, check the big end for vertical play, dont fret about lateral.
With the barrel off , and a bare head lap the barrel onto the head with coarse paste, ( Valve grinding paste will do, apply the paste to the inner section and let it work out to the outer, lapping involves placing the head on the barrel and oscillating the rub about 45 degrees , give it 30 cycles and check, an uneven finish means more lapping and a warped head.

Option 2 requires a bucket of hope, believe everything is OK and box it up and try again.
This seldom works.

Worry and ask about refitting the barrel later. I suspect the previous owner seldom used the bike , trailer show queen, all show no go. If you want to ride it and feel good , look at the guts and make some tough decisions. its the battle of entropy and enthalpy.


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Is that ring that I found between the head and barrel supposed to be there? Upon closer inspection it isn't perfectly round on the outside edge, and the Book of BSA and the spares catalog don't show it. It's at least 1/16 thick, so in addition to creating a leak, could it also be affecting the timing?

Last edited by SpencerAZ; 01/22/16 8:40 pm.

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As requested. Piston is marked "020":

[Linked Image]

[Linked Image]

Last edited by SpencerAZ; 01/22/16 8:57 pm.

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Spencer,
before you lift the barrel off get a cloth rag and put the piston to T.D.C. Ease the barrel up enough to get the rag stuffed in under the barrel in around the mouth of the crank case and the con rod. When you lift the barrel on up if there is any broken compression rings or oil control ring, they now wont fall into the crankcase and cause you more hassle getting them out.
Follow Chaterlea25's advice about sealing the head to the barrel, he knows what he is doing. Also intake valves on most engines are bigger than exhaust valves, that's just the way it is. Also your barrel should now be slack the way yours is since you have the head off, like I said in my previous post the head has to be tightened down to hold the barrel on.

With regards your piston its in my opinion the top two ring groove widths are more important than anything, they should be 1 or 2 thou bigger than the piston ring thickness, top groove always wears more than the second groove and the second groove always wears more than the third groove. If the ring isn't a snug fit in the groove then it slaps up and down when the engine is running which wears the aluminium piston groove even more which can lead to broken rings. If you take a compression ring off the piston and place it into the barrel and push the piston against it to square it in the bore you will see what the ring gap is depending on how much the bore is wore and how much the ring is wore, the two ends of the ring should be almost touching each other on a new bore with a new ring, in a worn engine they will open up and allow compression to escape.

In theory no part of the piston should ever touch the bore, its the piston rings only that should touch the bore, in practise there is the odd engine that something goes wrong with and the piston touches the bore, you see the scuff marks on the piston skirt when you pull it apart for a rebuild and you wonder how it didn't seize itself. I have rebuilt Komatsu loading shovel engines with 24,000 hours on them that the pistons looked to the naked eye as shiny and brand new as the first day the engine was built. Apart from some soot on the piston crown and combustion chamber, the only thing wrong with them was the ring grooves were 10 to 15 thou wider than the new rings so they were scraped.

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Just seen you new post and pictures, to answer you question, no there should not be a ring between the head and barrel, if the piston was hitting the head for whatever reason you place a shim under the barrel to rise both barrel and head up. This would be a common thing when putting a Triumph T120 piston into a B31 engine to give you 400 cc as opposed to the standard 349 cc. It takes a 2mm thick shim to do it in the case of the B31.

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I'll be pulling the barrel off tomorrow and I appreciate the tip about the rag. Additional photos and perhaps a video will be provided. Also, I did that petrol test on the head and nothing leaked past the valves.

I know this is just wishful thinking, but is it a possibility, however remote, that the ring in the head is the source of my problem? It would certainly affect timing, compression, and interfere with a clean seal at the head; a combination that would almost certainly prevent an engine from running properly. The condition of piston crown, valve seating and the mild carbon buildup seem to indicate otherwise normal operation. I'm just trying to find my silver lining, haha!

Last edited by SpencerAZ; 01/22/16 10:40 pm.

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Could you be more specific about inner and outer face? Am I applying this to the head, the barrel or both? Is the fine applied to the flat face and the course to the perpendicular edge? I'm trying to be clear because I'll be taking a crack at this in the morning.

Last edited by SpencerAZ; 01/23/16 2:27 am.

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I had one of these as my first bike about 50 years ago when I replaced rings with out a ring compressor I would individually compress each ring into the cylinder and then position the cylinder and piston on the rod and slide the pin in then fit the remaining circlip ,after you bin that ring between the head and cylinder be sure to reset your tappets from memory they had 3 thou clearance .

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I'm sure this doesn't make much difference, but my motor is stamped "HC" above the serial number. High compression I assume? By how much, I'd like to know, but also wonder if there is anything specific to these engines I should look for in the way of faults or parts.


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Here's a link to a photo album for this thread. The piston, rings, and barrel all look good. I measured the barrel N, S, E, & W, top and bottom, with a caliper and the gap is the same. Retested the valve seat with petrol and still does not leak. Found the barrel to case gasket was only partially complete and filled with Permatex. I've ordered a proper gasket set from the UK before I put anything back together. What else do you gents think I should be checking for. Besides that ring that shouldn't be there, I'm not seeing any obvious flaws.

http://s1318.photobucket.com/user/SpencerAZBSAbucket/library/Mobile%20Uploads


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