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Messages - Steve.S

#1
Pre War / Re: Sloper Barrels / Pistons
05 November, 2024, 18:20:39
Aha. That makes a difference. So in theory the barrel is 0.010" over, which is a little on the high side. It might smoke a bit. However, you need to measure your piston carefully at right angles to the gudgeon (wrist?) pin to get the actual clearance, but if you might want to give it a run or two at Bonneville, 0.010" might be OK to prevent it from seizing! LOL.
I get the impression you are in the good 'ole USA with your Wisconsin piston?
There is a company in the UK, F.W Thornton 01952 252892. Email ENQUIRIES@FWTHORNTON.CO.UK
I understand they have the 493cc OHV Sloper piston in stock. Hepolite Part No. 2687. Apparently these are newly made in Australia, and have 2 compression rings and 1 oil control ring. However I don't know if the control ring is at the top or bottom. If it's at the top, you're laughing, because all you'll need is a rebore.
They stock Std, +0.020 and + 0.060. The compression height is 1 1/2" and the gudgeon pin is 3/4" dia.
They also stock liners. The piston will be quite expensive, but what price Fun?
Hope this helps. Let us know how you get on.

 
#2
Pre War / Re: Sloper Barrels / Pistons
05 November, 2024, 02:22:12
It seems to me that there is something rather strange here.
The 1929, 1930 and 1931 Parts book show the same Part No. 24-6 for the barrel.
The 4.93 OHV Sloper barrels I'm aware of have 10 fins, so I don't know what your 9 fin barrel is off. Surely, If BSA had altered the number of fins, the Part No. would be different? Who knows?
My view is that the damage to the 1930  barrel will not cause a significant problem, because I don't think the rings will reach the damage. I think you could clean up the damaged edges and put a chamfer on the inside. However, if you fit a piston with an oil control ring at the bottom of the piston, it may well catch. (But see below, re fitting a liner).
I have been using a 2 compression ring piston for the last 30 years, and haven't had any problems. Yes, I sometimes have to adjust the oiling if it smokes too much. I find the adjuster is quite sensitive. Can't really see the damage to the 1931 flange. There seems to be a brass shim covering it?
Now, I failed my 11+ maths exam, but as far as I can see, 80mm is 3.149", so it is 0.008" larger than the figure you give of 3.141". In terms of bore measurement, this is quite a lot.
I wonder if you have been using a pair of callipers to measure the bore, because with a bore of nominal 80mm diameter, plus a clearance of say 0.005", the actual bore size will be larger than the 80mm you have measured. (unless BSA made some undersized barrels?)
In theory, 80mm + 0.020" oversize would mean a rebore to 3.169" plus clearance. Plus 0.040 would give 3.189" and plus 0.060" would give 3.209" + clearance. Are my calculations correct, or have I missed something?? However, a rebore should always be done to the actual piston size.
I think you will need to sleeve either of the 2 larger bores. I used a Hepworth liner, and it didn't break through, but other liners may have larger OD's and break through.
I hope I've got the above correct. If not perhaps some kind gent could put me right.
Your best bet is to take the piston and barrel to an Engineering shop and get their advice, but they won't like the damage.
#3
I think you could answer your own question regarding spitting back by fitting the choke slide, and see if it makes any difference.
You are quite correct in saying that a higher Octane Rating decreases the likelihood of Pinking.
It is a common belief that Pinking is caused by Pre-ignition. It's actually caused by Detonation (otherwise known as Knock). They are two different things, although linked.
The mixture is ignited by the spark plug, and as the Flame Front travels across the combustion chamber, the unburnt mixture in front of it spontaneously combusts, producing a high pressure wave, which, when it hits the cylinder wall, produces a 'Pink' sound. This is called Detonation, and is usually caused by over advanced ignition.
Pre-Ignition, on the other hand, is usually caused by a hot spot, and produces no sound. At it's worst, it will reduce engine power, or even cause the engine to stop.
Pre-ignition can cause Detonation, hence the link.
It was found that raising the Octane number of the fuel reduced the likelihood of detonation (as you say), allowing raised Compression Ratios and more timing advance, thus increasing power output.
Auto-ignition is not a word much used in the UK. (Perhaps in the USA?).
Auto-ignition is when the engine continues to run when the ignition is switched off. It's usually referred to as Running On in the UK. I have never seen a British single cylinder motorcycle engine 'run on'. It seemed to be more common with Motor Car engines in the '50's due to carbon build up and insufficient cooling.
Auto Ignition is also linked to Pre-ignition.
If you are interested in the combustion process, you can do no better than investing in a book by Sir Harry Ricardo "The High Speed Internal Combustion Engine", but it is a weighty tome.

Anyhow, enough of all this technical bo****ks, as long the thing starts, get out there and enjoy it while you can, but try not to let it pink.
#4
Pre War / Re: Crankcase bearings
02 November, 2024, 03:23:51
At the begining of the '30's BSA changed the bearing arrangement a few times.
For the last 30,000 miles, I have been using 2 roller bearings and 1 ball bearing. The ball bearing is fitted first, followed by the spacer ring and then the roller bearing. The other roller bearing is fitted to the other side. The roller bearing I used was an NSK NF305.
The bearings are 25mm bore, 62mm OD, 17mm wide.
However, the 'Motorcycling' article dated may 19th 1955 states 2 ball bearings and 1 roller bearing. If you search the Forum you should find it.
Then there is an article in 'The Motor Cycle' magazine dated September 1932 quoting a ball and roller on the drive side and a roller on the timing side, and this is the arrangement I have used, so it's up to you.
The crankshaft Main Shaft referred  to will be the drive side engine shaft.
Having 3 ball bearings will probably be OK, but a roller bearing is better able to take the drive thrust.
The bore of the shims will be 25mm to fit the mainshaft and the OD will be the OD of the inner race of the bearing. 
#5
Pre War / Re: Spanner nut removal scocket
31 October, 2024, 18:27:28
As you've shown me yours, I thought I'd show you mine. As you can see, it took but a few moments to make, and works well. But please bear in mind that I am both a Dullard and a Bodger.
It seems to me that the Peugeot item will have a metric hexagon, necessitating the purchase of a metric socket. But I suppose you could use a pair of Stilsons, like what I do.
#6
You definitely seem to be getting there. Keep at it.
I strongly advise fitting the choke, it may well solve your problem. I wouldn't spend any more time trying to diagnose the spit back until you have done this.
Closing the points will retard the ignition a tad, which is the direction you need to go, although, as far as I can gather, it no longer kicks back?
Yes indeed, the suggestion is a work-around, although it may be necessary even when you have fitted the choke.
Your head is correct in thinking that the highest revs adjusting the mixture screw, gives the correct mixture on tickover. To fine tune, lower the idle screw to get the lowest tickover, and adjust the air screw again.
It's just a question of fiddling about until you're satisfied.
Regarding ambient temperature, I've found this normally affects the older water cooled motor car engines, rather than ancient air cooled motorcycle engines.
In my view, the issue of ignition timing with E5 or E10 is more to do with Octane rating than burn characteristics. But what do I know?
Personally, I have so far never had a problem with E5, or found the need to retard the ignition on many different British motorcycles, but then I use an Octane booster, and can only speak for myself.
If the engine doesn't 'Pink' on E5, then the ignition doesn't need retarding.
I hope this is helpful.
#7
Yes, I would say you have retarded the ignition. You make no mention of using the choke. Does it have one?
It's good to give it a run, but you could easily warm it up in the garage.....depending on the neighbours.
Bear in mind the mixture screw is an air screw, so you might want to screw it in a tad more to richen the mixture if it still spits back.
If you're sure you have no air leaks, you might consider a richer slide.
#8
Singles / Re: How not to B33!
31 October, 2024, 00:41:53
Very glad to be of help. You're doing a fine job, made more difficult by having to source parts from overseas. I admire your perseverance.
Make sure there is a very small amount of clearance between the teeth of the inlet cam and the idler gear. If there is no movement, you need to investigate further.
Powodzenia.
#9
Correction. For Base Plate, substitute Cam.

For clarification, when you turn the cam by hand, it will only turn one way against the springs. That is advancing the timing.
#10
Very easy to get a muddled head. Happens to me all the time.
I wonder if the following might be helpful?
Viewed from the timing side, the engine rotates clockwise.
As far as I can see, the cam rotates anticlockwise.
So, moving the base plate clockwise will advance the ignition.
Moving the plate anticlockwise retards the ignition.
When everything is tightened up, you can easily confirm this is correct by trying to rotate the base plate anticlockwise, but it will not move. If you rotate the plate clockwise, it will move against the action of the return springs, i.e advancing the ignition.
Always rotate the engine clockwise when moving up to the timing mark.
If you use a wedge to keep the points advanced, don't forget to remove it after you have set the ignition.
If you find that you need to advance the timing from the original position, this may make the kick back even worse, and we will have to have a rethink.
Finally, bearing in mind you will be trying to start the engine on full retard (and this is when it kicks back), it might be worth checking where the timing is on full retard. It might give us a pointer. Or, indeed, is  the timing advancing when kick starting, perhaps due to worn springs. Just a thought.
#11
Twins / Re: '69 Firebird Scrambler
26 October, 2024, 18:49:45
Good man. You say screws 1 1/2 turns out. This is only a starting point. They should be quite sensitive to turning. Set each one to highest tickover speed and then reduce throttle screws as required. Apologies if you already know this, but I obviously don't know how much experience you have.
It's well worth checking the float heights. Bushman tells you how.
Assuming the slide is not worn, spray oil onto the flanges and spray grease onto the inlet valves, to check for air leaks.
If you are able to get it to tick over, place a hand behind each exhaust to be sure they're even.
Does your carb have removable pilot jets?
#12
Twins / Re: '69 Firebird Scrambler
26 October, 2024, 13:36:18
It might be worth searching the internet for "Bushmans Carb Tuning Secrets".
This will show you the idle passages, which may be blocked? After blowing out, I spray WD40 into them so I can see they are actually clear.
#13
The Star and Garter / Re: Posting photos
26 October, 2024, 01:49:47
Aha! I see the image is there.
This is how I did it.
Click "Drag files here"
Picture file comes up.
Right click on selected picture.
Click "Open".
Picture appears in another window.
Right click on window.
Select "Resize" and use bar to decrease size.
Click " Save".
I think you have to rename this picture, otherwise it will over write your or1ginal.
Go back to picture file, locate renamed picture.
 Double click on image and picture will appear in Reply.
I'm now going to try it again.....
Thanks Dave. I appreciate your help.
 
#14
The Star and Garter / Re: Posting photos
26 October, 2024, 01:31:16
Dave,
You ask if this is what is on my screen, but there is no image in your reply.
However, if this reply has an image on it, I've cracked it.
#15
The Star and Garter / Re: Posting photos
25 October, 2024, 19:56:47
Yes, I do now, but didn't before. Don't know why that is.
When I click on it now, it comes up with my pictures file folder, and I can click and drag pictures from there. However, in this folder, there is no option to reduce the file size, as there is with my other method (which won't drag the image to the reply box). Please bear in mind that I am a simpleton.