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Messages - Jim S

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Singles / Re: B31 leaking head bolts
« on: 28 September, 2020, 18:02:58 »
I wasn't getting much visable smoke either, but the inside of the tail pipe was oily soot. Also the spark plug was very sooty.

Have you checked the rocker oil feed and drain lines for leaks?

Check around your barrel. If the oil is starting just below the head/barrel joint, it is coming from the combustion area. Also, the same oil gets blown back on the carburetor, dynamo, magnito, battery making a sooty mess of the area. On every ride I was getting a little river of oil running down the crankcase just below the forward left head bolt making me think that the oil was coming from the barrel to crankcase joint, or the bottom of the head bolt inside the crank. But not in my case. It was running down the head bolts from top to bottom.

Singles / Re: B31 leaking head bolts
« on: 28 September, 2020, 13:20:46 »
I had this problem on my 1949 B33. In my case there were 2 potential causes.

The cup washer that one of the valve springs sits in was partially blocking the oil drain hole for the rocker cavity. It could cause excessive oil accumulation in the cavity which could migrate down the valve stems into the combustion area. This was addressed by drilling a champher on the drain hole.

The other potential cause was a poorly reamed hole in the head for the exhaust valve guide. Oil was flowing down between the valve guide and the head. The machine shop bored an oversize hole in the head and installed a new guide with a viton seal.

After these improvements were made the engine is surprisingly dry.

Singles / Re: 1953 Plunger B33 gearbox oil leak level
« on: 08 September, 2020, 03:17:18 »
See this post:
A brief summary:
Put 400ml of oil in the gearbox, or fill to about 1.0 to 1.2 inches below the gearbox main shaft centerline.

Singles / Re: B31 - gearbox oil leak
« on: 07 August, 2020, 21:51:49 »
With 320ml in the gearbox, it would be interesting to know what the measurement is between the centre of the main shaft down to the oil level, and compare this with the radius of the bearing.

Singles / Re: B31 - gearbox oil leak
« on: 04 August, 2020, 21:01:46 »
In the link I added above, it indicates that 370-400ml of oil brings the oil level in the gearbox to about 1.0-1.2 inches below the centre line of the main shaft for the older style gearboxes with the round screw on cover on the right side.

This is very easy to check. The bike should be vertical. I use a nylon tie wrap as a dipstick, push it down vertically into the oil, press it against the clutch adjustment bolt (which is at the centre of the main shaft) with my finger tip at the centre of the bolt. Pull out the tie wrap and measure the distance from my finger tip to the oil on the tie wrap.

I use SAE50 in the gearbox.

Singles / Re: B31 - gearbox oil leak
« on: 03 August, 2020, 01:32:42 »
Check out this previous post. Maybe you are putting in too much oil.

Twins / Possible Damage to Forks During Transport
« on: 27 July, 2020, 18:45:05 »
I had a flat tire last week and had to have my 1957 A7 transported home on a flat bed tow truck. I think the driver may have been a little to aggressive on cinch down of the front end because now, in the garage, I have two little puddles of oil on each side of my front wheel.

Has anyone had this happen? I am wondering what kind of damage has been done to the fork assemblies. Is it possible that oil was forced through the seals without actually causing damage, and the oil I am seeing is what accumulated in the chrome seal housings. Is this thinking too optimistic?

Singles / Re: Stands.
« on: 09 July, 2020, 00:21:03 »
For getting my B33 up on the centre stand at home, I have made a small ramp. About 1 ft wide, 3.5 in high at one end and at floor level at the other.
Push the front wheel up the ramp, put on the front brake, push down the centre stand with your foot, grab the rear hand rail and pull back. The bike goes up on the centre no sweat!
I still need my wife to help me get it off the stand however.

Twins / Re: Carburetor Float Needle and Seat Washer
« on: 03 July, 2020, 12:14:49 »
Thanks Julian
I have no recess, so no washer.
However, where is this thin/thick o-ring?

Twins / Carburetor Float Needle and Seat Washer
« on: 03 July, 2020, 02:14:10 »
I have a 1957 A7 with a 376 carburetor. I just installed a new float needle and seat adapter, however I'm not sure if I should install a fibre washer under the seat adapter. The Amal site shows a fibre washer but says "If fitted". Draganfly says to install a washer if a Teflon tipped needle is installed. I have another document showing an exploded view of the carburetor and no washer is shown.
If a washer is installed, I expect that the fuel level in the float chamber would increase by the thickness of the washer.
How do I determine if I need this washer?

Singles / Re: Stalling
« on: 28 June, 2020, 14:16:10 »
In addition to all the above, I get more consistent results for setting idle if I use 91 octane fuel with no ethanol.

Singles / Re: Bsa b33 1946/48 gearbox
« on: 24 June, 2020, 02:27:29 »
Try building the gearbox without the shims.

Also, try building with just the main shaft the the main shaft plus selector shaft.

Singles / Re: B31 oil leaks
« on: 20 June, 2020, 12:57:38 »
Hello B. Murphy
The older configuration gearbox spews out oil if you put 1 pint in per the BSA recommendation. See this post for more info:

For the primary, put in the minimum amount of oil. The level should just touch the bottom of the chain. On my C11 I have stopped putting oil in the primary and periodically lub the chain with rear chain lub. Ensure the clutch bearing has grease however.

For the engine, it is best to do some investigating to determine the source.

Singles / Re: ZB 32 gearbox
« on: 17 June, 2020, 20:00:38 »
Hi Dennis
Where did you buy the selector forks? I had to have mine repaired because I couldn't find any.


Singles / Re: Bsa b33 1946/48 gearbox
« on: 17 June, 2020, 02:38:52 »
Could be the shifter forks are not sliding freely in the dogged wheel slots. Caused by:
-bent forks
-incorrect shimming of the shifter shaft

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