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Topics - Bles31

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Singles / Gearbox oil leak
« on: 24 April, 2020, 10:49:27 »
In the current lockdown I decided to revisit my gearbox oil leak. I pulled the clutch etc off and the final drive sprocket, exposing the gearbox. By measurement at both sides of the box I have found that when I fill the gearbox (B & M group plunger 1938-63 on the Draganfly website) to the bottom edge of the filler port, the oil level is:
12 mm above the lip seal where it sits on the drive sprocket
9mm above the splines between the sprocket and the output gear
5mm above the bush between the mainshaft and sleeve gear (items 97 and 98 on the dragonfly parts list/diagram). The bush, item 103 seems a good fit.
I filled the gearbox to the bottom of the filler port then sat and watched. Cold oil, Duckams 20-50, seeped out of the splines at the sprocket and from the bush/shaft interface
Slipping the sprocket into place and nipping the nut up seemed to sort the splines seepage. I expect it might seep thin hot oil, but hopefully not to any great messy extent ( or am I wrong?)
Currently I'm thinking my biggest leak is from the bush area, which is predictable as there has to be some clearance there and hot oil will find it. My question (eventually) is whether the felt and cork  sealing rings which sit in that area when the bike is assembled actually prevent leakage, or  is the leak inevitable? It seems a pretty crude seal system given that it sits flooded when the gearbox is properly filled. Am I missing a  trick somewhere? I can  run the bike with 10 mm less  oil in the gearbox as I only do short cafe runs at present, but I would like to achieve better than that.
Any advice welcome as this is a major pain as I don't like to park up and drip oil around the place.

Singles / Ammeter reading
« on: 13 April, 2019, 12:58:48 »
Just fitted new battery and Dvr2 regulator to my 1954 B31. All seems OK apart from the ammeter reading which flutters around zero until I've ridden a few hundred yards or revved the bike for a while on the stand. It then settles down and shows a steady charge. Once it settles down it stays good. It was doing this on the previous regulator. Is my dynamo misbehaving?

Singles / Voltage Regulator
« on: 22 October, 2018, 17:55:52 »
Last week I found my battery flat (B31 with Thorspark ignition).When I tried to charge it the charger declared the battery failed and cut out. The battery is 2yrs old and has a less than ideal time, having been charged, left to go flat , charged etc. The bike has a fairly cheap voltage regulator fitted in place of the old electro-mechanical original. Before I get another battery I am interested to hear views on cheap vs pricey solid state regulators. Are there any I should avoid, any which are generally recognised as being best?
Having fitted electronic ignition I am keen to have a good battery. And yes, I'm wondering about having the magneto overhauled to avoid all this. But it's more money!

Singles / Centre stand B31 (1952 plunger)
« on: 14 July, 2018, 20:05:52 »
I have tremendous trouble getting my B31 on and off its' centre stand. When the bike is on the stand both wheels are on the ground. I can't feel any severe wear in the stand or it's pivot, but haven't actually stripped it down yet. Does anyone have dimensions for this stand ( leg length in particular) as I'm beginning to think its too short. Or perhaps there is a stop missing which is letting the bike go too far over centre and settling too low at the rear. Any help gratefully received as this is going to do my  back in one day!

Singles / Gearbox oil seal
« on: 17 May, 2018, 19:55:13 »
Had a search and this has been discussed before - but I can't find a solution.
I replaced a  leaky oil seal on the output shaft of  my '54 plunger B31. The leak persists! The seal is fitted nicely, square to bore and just below flush with gearbox case. Sprocket shoulder the seal contacts is in good condition and I have a felt and cork seal on the output shaft - which I think is intended to seal off the end of the shaft splines. I've looked at this again and again and can't work out why the leak is there and so  bad.

A few factors - I filled the gearbox to the level of the screw in inspection port on the right hand side of the gearbox as advised - this fills box to just about the level of the oil seal on the left side. Should I try less oil?
                      Ive read about putting grease into  gearboxes - possibly reduce leakage, but not something I've done before.
                      The oil seal is meant for a shaft diameter of 1.625 " (according to the size marked on the seal - which I believe refers to the associated shaft diameter not the seal size.) but the shoulder on the sprocket is 1.722" - not a lot different, but the old seal looks a bit stretched when I try it on the sprocket -         has anyone a sprocket they can measure for  comparison (I may be over thinking this!). Puts the shoulder on my sprocket at  between 1 5/8" and 1 3/4" which seems a strange choice for an old  british bike.
I can just let it leak but would rather not. Any advice welcome.

Which BSA do you ride? / My B31
« on: 11 September, 2017, 13:47:53 »
Hello  there.
This is my  1952 B31 which has been living in my garage virtually untouched for 12 months. I've just recently got it running, but a few jobs to do. You might notice front wheel is well off centre - nearly touching right hand fork. Looks like it's not charging very well, but basically it seems a sound bike which I want ready for cake shop adventures around the Lake District next Spring.

Singles / B31 stand
« on: 21 August, 2017, 16:23:05 »
Hello - this is my first post. I have a 1952 B31 which I am currently making roadworthy. I will be putting it on the road to use regularly -  mainly to visit cafes and cake shops around the Lake District. One of my major problems is the lack of a useable stand so that I can work on the bike. It's currently leaning against the wall, which isn't convenient.  The bike has a centre stand but this offers no leverage at all and I find myself having to lift the weight of the bike to get it up on the stand. This is too much for my 69 year old back! Despite searching around I can't find a side stand to fit the plunger frame. Can anyone advise on side stand, source of better centre stand, mod's ?
Thank you.

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