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Messages - Mike40M

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46
Singles / Re: need help to buy a small new lathe
« on: 02 January, 2021, 02:05:42 »
One thing I've noticed is that many small chinese lathes can't make single point 26tpi threads. Worth checking before buying. Though most times you can make BSC threads with taps and dies.


47
Twins / Re: Popping on over-run.
« on: 18 November, 2020, 12:36:01 »
I've used a high temperature silicone for head to downpipe on a B40WD and a RG250, worked ok. Also used it on downpipe to silencer joint on a Manx, a Vincent and a Ninja.

48
Singles / Re: First restoration project advice
« on: 13 November, 2020, 13:57:03 »
In my limited experience from having half a dozen old british bikes, mostly running ones, I'd say that even so called restored bikes need a lot of work to run well. A basket case usually miss some almost impossible to find parts. So I think you should consider going for a running one. Life is too short for not enjoying riding them. Yes, I'm a M.Sc. Mech. Eng. too.
At present almost finished work on a Victor Special  which I bought to replace the one I bought new and melted down in a barn fire in -83.

49
Singles / Re: b25ss not starting after rebuild
« on: 10 November, 2020, 09:03:19 »
I think that your problem is carburettor related. A number of people have been complaining of problems with new carbs. Inspection and cleaning seems necessary.
Just to get a bike running, ignition timing is not that important. My Manx starts happily with any timing between 40 degrees BTDC to 12 AfterTDC.

50
Singles / Re: Rigid B33 Primary Chain?
« on: 13 October, 2020, 10:42:29 »
Oops! Made an error. Last sentence should be:
A 1/2x5/16 chain is equal to a 425 chain.
Sorry

51
Singles / Re: Rigid B33 Primary Chain?
« on: 13 October, 2020, 06:53:15 »
Your not the first to be confused. Motorcycle chains was earlier measured by pitch and width in inches. Since most people in the world are unfamiliar with thinking in fractions of an inch, a decimal looking system was introduced.
The first digit tells the pitch in eights of an inch. A 1/2" is now a 4xx and a 5/8" is now a 5xx chain.
The second and third digit tells width, also in eights of an inch. 1/4" becomes 2 eights, so x20. 5/16" becomes 2.5 eights, so a x25. A3/8" width becomes a x30.
So you are correct that your 1/2x5/16 chain is equal to a 525 chain.

52
Singles / B44 VS needs new rear chain
« on: 08 October, 2020, 20:11:21 »
I found the rear chain on my Victor Special was uneven stretched. Worst I've ever seen.
What do you suggest is the best replacement?
Go for an unsealed (open) chain as per original. Most efficient transmitting power to the rear wheel, but quite a lot of maintenance. Uses it on my Norton, Honda and Yamaha race bikes.
Or a modern O-ring or X-ring chain. Easier maintenance. But some are wider, problem on the roadgoing Norton, grinding on inside of the primary chaincase. Don't know if it's more space on the BSA, anybody knows?

53
Singles / Re: Gear oil leak (1965 B40F)
« on: 06 September, 2020, 18:25:49 »
Of course it can leak anywhere. Usually seals. not mating surfaces, bypassing screws and even through bad castings. Are you certain that it's gearbox oil? Had a hard to find leak on my B40 from a faulty inlet oil rubber pipe. Dripping from footrest bracket.
Two of my eight British bikes don't leak. A Norton twin not finished restoring, no oil in it to leak and a Manx with a Molnar engine. Just lying, after a full race season one drop of oil from the rev counter drive.
Wife don't understand why oven trays disappear.

54
Singles / Re: Alternator wiring
« on: 25 August, 2020, 10:36:43 »
I've never fully understood how the Lucas light switch works, so I only guess that the third alternator wire (GY) goes to #17 on the switch. By magic it's connected to #7 when headlamp switched on and then is wired (GB)  to the rectifier.
If I'm barking under the right tree, the additional third wire is also rectified to DC. So no AC to the lamp.
The original design is made to give the right supply to ignition and charging (without overcharging) the battery. With headlamp on, additional power was switched in.
The B40 WD which has a 12V two wire alternator (always full power) uses a zener diode to dump excessive power, not to overcharge the battery or blow lamps.
A common way of improving the charging system is to fit a regulator/rectifier unit (both 6V and 12V available) replacing rectifier, zener and the detour via the light switch. Then two of the alternators three wires are joined, making it work as a two wire alternator.
I've not made that mod on a 3-wire stator, so i suggest you get advice from a more knowledgeable person.
Both Paul Goff, http://www.norbsa02.freeuk.com/ and Alan Osborn, http://www.aoservices.co.uk/ are known for giving good advice.

56
Singles / Re: Fuse question
« on: 18 August, 2020, 07:00:30 »
It's a common practice to fit an in-line blade fuse holder fitted directly to the battery. Primary function is to protect when shorts occur. So if your ammeter goes to 10 Amps, a 10A fuse will be fine.
But since the horn and brake lamp is connected prior to the ammeter, more current might occasionally be drawn. So a 15 Amps might be needed (probably not). In case of a short, a 15 Amps fuse will blow as well.
The secondary function of a fuse is to protect wiring from overheating. The original wire gauge was selected to keep voltage loss low. Which makes wire heating low. But if you have fitted heated grips, extra lamps etc. it could be a problem. Fitting indicators don't affect wire heating much as current is intermittent and only for short times.
So if you are a belt and braces type, an additional smaller fuse could be fitted on the outgoing side of the ammeter. But as a fuse have a resistance so that excessive current melts it, it gives a small voltage loss to the lamps.
My advice is that you fit a 10 A fuse and have a 15 A fuse in your pocket. If it works you could try with a smaller one.
Keep in mind that that if your battery is almost flat, the charging system will push as much current as it can into the battery. Probably enough to blow a 5 Amps fuse.

57
Singles / Re: B40 nut size
« on: 27 July, 2020, 08:01:35 »
What year is it? During their production years, BSA made a lot of changes on them. Could even affect nut sizes.

58
Singles / Re: Spark plug cap... good vs bad ?
« on: 20 July, 2020, 04:34:52 »
It all started when car radios became more frequent. RFI (Radio Frequency Interference) emanating from ignition systems, became a problem. Later when electronics became more common in vehicles, RFI problems got worse.
The solution was to put an resistor in series with the spark plug. Usually about 5000 Ohms. Three ways came into use. Resistor spark plug cables, where copper wire was replaced with graphite. Quite unreliable. Resistor spark plug caps. Last came resistor spark plugs. You shall not combine resistor spark plugs with resistor caps or resistor cables.
Different types of ignition systems should either have resistors or not. I've read that Magnetos don't work well with resistors. Coil and breaker systems can work with or without resistors. Different opinions on which is best. Some electronic ignition manufacturers say that they should be used.
I've read that NGK recently discontinued at least one type of nonresistor plugs common for classic motorcycles.

59
Singles / Re: Clutch oil seal and sleeve gear bush
« on: 16 July, 2020, 17:16:28 »
"And I imagine you're running out of things to suggest?  Phil"
Not a chance, this is an internet forum. Stupid suggestions will never end. Especially during lock down, with nothing else to do.
It could be that the oil close to the leak is not yet contaminated by the dye. A long ride might show.
Had a bad leaking Burman gearbox. Solved it with filling it with the correct semifluid grease. Now almost oil tight.

60
Singles / Re: Primary chaincase plug screw - breather hole?
« on: 15 July, 2020, 19:36:42 »
As said by AJWDThumper, "To avoid oil leaks, it needs any breather to vent into an expansion chamber with a drain hole back to the sump or to vent back to the oil tank "
The 69 and -70 B44 breathed plug does exactly that. The three holes on the inside venting into the small chamber in the plug. The lowest of the three acts as a return for oil. And the hole to the outside releases any internal pressure. Normally there is very little if any overpressure in the primary.
I don't remember noticing any oil coming out there on my first B44VS. But that was a long time ago.

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