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Messages - Jim S

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Singles / Re: M33 Magneto points gap
« on: 14 June, 2020, 13:37:11 »
Hi Rog1
My Service Sheet 604 indicates on the first page that it was revised in 1958, so it should be applicable to your bike. If you have the face cam configuration, you should use the non G.B. method (the first one listed in 604).
One point not mentioned in 604 is when turning the engine back to get the 7/16 btdc, I turn the engine back beyond 7/16 then turn it forward to 7/16. This takes up the backlash in the timing gears.
I use Service Sheet 604 to set the timing on my 1949 B33 and it starts usually first kick with the timing set at about half advance. I ride it fully advanced.
Good luck.

Singles / Re: M33 Magneto points gap
« on: 10 June, 2020, 12:54:46 »
Hi Rog1
I'm not sure if it is at 12 o'clock but it is easy to figure it out. Just determine where the high spot is on the face cam. That is where the points are fully open.
Have you checked the magneto timing? If this is not set properly you can overheat the engine. For my B33 I use service sheet 604.

Singles / Re: ZB 32 gearbox
« on: 27 May, 2020, 04:16:45 »
Hi Dennis
Have you separated the 3 shafts? You should look for wear on the fork faces and wear in the groove of the 1st/2nd dogged wheel. I had to replace a dogged wheel on my gearbox and weld repair and machine the corresponding fork because of excessive galling caused by poor alignment and rubbing of the fork and dogged wheel.
Also ensure the fork bodies slide smoothly along the gear selector shaft and there is no binding of the pins in the fork body grooves. If you feel any binding you can do some filing or very light blending to remove any raised areas that may be causing hang up of the pins in the grooves. Look for wear on the pins and grooves also. If you see any issues you may need to drive out the pins on the gear selector shaft to remove the forks.
Check that the dogs on the dogged wheel engage nicely with those on the face of the 2nd gear. The dogged wheel should also slide freely on the shaft.
See Service Sheet 608. I think it says the assembly should be in 4th gear when you stuff the 3 assembled shafts into the gearbox housing.In 4th gear the 1st/2nd shifter fork and dogged wheel should be mid way between the 1st and 2nd gear. If not you may need to add or remove a shim.
Push the inner cover into place including the gasket and install a couple of bolts. Try shifting gears while spinning the rear wheel or output sprocket. Everything should turn freely with no binding or resistance in all gears and in neutral. Spin the main shaft in neutral to feel for binding. If you feel binding, you may have a bent fork or slight misalignment. I had slight binding on my repaired fork which I corrected by light blending of the fork face. This took about 6 iterations of removing and reinstalling the gear train/shifter assembly.
Check that the shifter shaft doesn't have excessive axial movement. I don't know what the limit is but my gearbox had 0.015 in. axial movement and it works fine.
My gearbox also had a chipped tooth on the ratchet lever which I believe caused the ratchet mechanism to skew and jam. I had the tooth built up with weld and refiled the profile.
After you install the outer cover, ensure you install a c clip on the gear selector splined shaft. Otherwise you can have ratchet misalignment.
These are the points I can remember when working on the gearbox in 2018. I hope it helps.
Let us know how you get along.

Singles / Re: Petrol tap repair
« on: 26 May, 2020, 03:41:09 »
A similar o ring solution was covered in another britbike forum. Here is the link.
The problem is the o rings get cut or nicked when they pass the small hole in the barrel of the tap.

Singles / Re: Rocker oil feed pipe (again)
« on: 16 May, 2020, 13:17:01 »
Yes, melt the joint and turn the T so it is pointing straight down. A simple propane torch will hopefully do it.

Or, with the T as it is now oriented and if you have the space, put a 90 degree bend in the pipe so it is pointing straight back, then curve it down and cross over under the inlet manifold.

Singles / Re: Rocker oil feed pipe (again)
« on: 16 May, 2020, 12:10:51 »
Hi Phil
Maybe if you heated the T so it pointed downwards, then bend the pipe towards the back and cross over to the right side under the inlet manifold. See the attached. This is an A7 but it may work for you also.

Singles / Re: BSA M21 1953 skipping gear
« on: 12 May, 2020, 14:11:30 »
Hi P J
Your M20 gearbox has a different shifter mechanism from your A10. On the M20 gearbox there is an adjustable length link arm, but you need to remove the outer gearbox cover to get access. Service Sheet 306 fig B12 is a view with the outer cover removed showing the link arm.
However, I had a similar problem getting into 3rd gear on my B33 which has the same gearbox. Adjusting the link arm was not successful. I had to replace the 3rd/4th gear dogged wheel and the associated shifter fork had to have a weld repair and remachining on the faces.
Service Sheet 608 covers the disassembly and assembly. I didn't remove the gearbox from the frame to do this work.

Singles / Re: Gearbox oil leak
« on: 06 May, 2020, 02:04:47 »
Here is an update on oil levels after obtaining access to my A7:

The 1957 A7 has a later model pre unit gearbox distinguished by the oval oil filler cover retained by 2 screws. Later model B33s with swing arm frames also have this gearbox. I have owners manuals for 1963 B31-B33, 1963 B32-34 and 1959 A7 which all say fill to 400 ml. With 400 ml in the A7 gearbox, I measured the distance from the centre line of the gearbox main shaft down to the top of the oil level. 2.25 inches.

On the early model B33 gearboxes the oil fill cover is round and is screwed directly into the gearbox. I believe this gearbox is on plunger frame models. Any documents issued by BSA that I can find say to fill with 1 pint or 570 ml which results in excessive leaks.

Combining Bles31's measurements with 370 ml in the gearbox (say 400 ml to round it off) and adding the distance from the bottom of the oil fill hole to the main shaft centre line results in 1.06 inches from the main shaft centre line down to the top of the oil level.

So using the main shaft as a reference between the 2 gearbox types, by putting 400 ml of oil in the earlier configuration gearbox (oil level 1.06 inches from the main shaft centre) it will result in having more gearbox components submerged in oil compared to the later gearbox with the BSA recommended 400 ml. (oil level 2.25 inches from the main shaft centre). 400 ml also places the oil level close to or at the bottom of the lip seal at the gearbox output sprocket.

This justifies to me that 400 ml is a sufficient volume to replenish the earlier configuration (plunger frame?) gearboxes and the level can be monitored by measuring 1.00 to say 1.2 from the centre of the main shaft down to the oil level.

Any comments on the above?

Singles / Re: B32 - Heavyweight Gearbox Speedo Drive
« on: 30 April, 2020, 16:52:14 »
I had a similar problem on my 1949 B33. I my case the speedometer was very erratic due to the poor engagement of the cable into the drive at the gearbox.
I cut a sliver of about 0.005 in thick brass shimstock, folded it in half and jammed it between one flat of the square cable and the gearbox drive. I think I also put a bend at the top of the shim to help to hold it in place, sort of hung on the top ridge of the gearbox drive untill I could slide the cable in place. Anyway, not too eligant but it worked for me.

Singles / Re: Gearbox oil leak
« on: 29 April, 2020, 12:51:00 »
Responding to John's message, as far as I can tell, there are 2 types of pre unit gearboxes:
Up to about the early 1950's the gearboxes had a round screw on cap on the right hand side for the oil fill. This is what I have on my 1949 B33. Any documents I can find indicate the gearbox is to be filled with 1 pint of oil.
Around 1952 or so the gearbox changed. The oil fill port on these later gearboxes have an oval cover retained by 2 screws. Internally, the shifter mechanism is different. I have found conflicting documents on the volume of oil for these gearboxes. Some documents say 1 pint and some say 14oz or 400ml. My 1957 A7 has this type of gearbox and I put in 400ml and it doesn't leak (much).
I don't know how the internal volumes are related between the 2 gearbox types. If 400 ml gives the same oil level relative to the main shaft for both gearbox types, then for me that would justify putting 400ml in the older gearbox.
Unfortunately I don't have access to the A7 currently due to covoid 19 travel restrictions in Quebec, Canada.

Singles / Re: Gearbox oil leak
« on: 27 April, 2020, 19:07:14 »
To reply to part of Dave's questions, the problem with the B33 gearbox is there is no level plug, at least not in mine.
I think a big contributor to Bles31's oil leak is he is putting in far too much oil. In the original post at the top he indicates filling the gearbox to the bottom of the fill port. That results in the bottom of the lip seal and the gap between the mainshaft and output shaft are submerged in oil in the static horizontal condition. Of course oil will flow out.
However, he has included some important information. When he removed the drive sprocket, exposing the lip seal, oil drained out over the lip seal. When the oil level reached the bottom of the lip, he measured the oil level to be 12 mm below the filler port with the bike horizontal on the centre stand.
In my opinion, I do not think any part of the ID of a lip seal should be submerged in oil in a static condition otherwise oil will seep out between the shaft and the lip. So 12 mm below the bottom edge of the filler port would be a good place to start for oil level provided that this does not exceed 570 ml. The next time I change gearbox oil I'll measure what volume this gives.
However, all this assumes the bike is horizontal on the centre stand. When the bike is put on the side stand, oil will submerge the lip and will put a mess on the floor again.

Singles / Re: Gearbox oil leak
« on: 24 April, 2020, 14:19:55 »
I have a 1949 B33 and a 1957 A7.
All documents that I can find for the B33 indicate that the gearbox capacity is 1 pint or about 570ml. If I fill my gearbox with 1 pint I get significant oil on the ground and your measurements demonstrate why. Your measurements are probably with the gearbox sitting horizontal with the bike on the centre stand. They would be even worse with the bike on the side stand.

For the A7 there is conflicting information. Some manuals and service sheets say 1 pint and some say 400ml. In the Haynes manual for example on page 10 for gearbox lubrication it says "1 pint (570 cc) (actual capacity 398 cc)" which implies that if you put in 1 pint, you can expect to have 170 cc leak out. I put 400 ml in the A7.

In summary, I think 570 ml is too much oil for the B33. I overfill it with 500 ml of oil, let it find its level by running the bike and check the level frequently using a tie wrap as a dipstick in the filler hole to ensure the level has stabilized.

Since you seem to have a method to measure the internal levels, it would be interesting to know what the internal levels are with 400 ml of oil or what volume of oil is required to bring the internal level to the bottom of the output shaft?


Singles / Re: Carburetter
« on: 28 March, 2020, 20:08:01 »
Hi David
I have the same problem on a 289 carburetor. The threads just marginally grab. I have found that applying medium (blue) thread lock and gentle hand tightening works for me.


Singles / Re: M33 kickstart problem
« on: 26 March, 2020, 02:50:36 »
Hi Rog 1

I have a 1949 B33. Attached is a photo of the kick start pinion. You can see that the teeth are quite pointy. I believe this facilitates engagement with the kick start quadrant.
Your pinion appears to have a shape closer to a spur gear that should be permanently engaged with a mating gear.


Singles / Re: Rigid B31 rear wheel
« on: 27 February, 2020, 22:37:07 »
If you are against a wall, you could try machining off the old sprocket and weld on a new 42T ring. However heat from the welding may cause distortion.

I have a 1949 B33 plunger and for whatever reason, it had a 46T rear sprocket which I believe was fabricated per the above because this does not exist in the parts book. I replaced the brake drum/sprocket with a 42T assembly. This is different from your configuration however.

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