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Messages - Arthur

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Lightweights / Re: BSA Dandy Aluminium Cylinder
« on: 02 February, 2017, 23:12:35 »
It is interesting to see how much these service sheets reveal about the state of readiness of the Dandy when it was put into production in the 1957 season. Within months, they had to change the cylinder barrel design and they had to reposition the pivot points for both the centre stand and the rear brake pedal, the latter originally projecting up through the floor pan and then having to be moved to pivot above it. They also had to abandon the original hand operated starter lever and replace it with a conventional, albeit LHS, foot operated kickstart. One would have thought most of the problems should have been spotted during development testing?

I wonder if there are similar service sheets revealing problems with the introduction of other BSA models?

Lightweights / Re: BSA Dandy Aluminium Cylinder
« on: 02 February, 2017, 18:59:36 »

Many thanks for that. The second page seems to confirm that the early production engines were indeed fitted with chrome plated aluminium cylinders and also confirms that the Dandy went into production before adequate development testing had been carried out. A few months later, presumably after problems with the chrome coating, a change to cast iron cylinders must have taken place!

The chrome on my aluminium Dandy cylinder is badly worn in places and it's surprising that this wasn't changed to a cast iron one back in 1957. How this engine survived to the present day with its original aluminium cylinder is a bit of a mystery!

Lightweights / BSA Dandy Aluminium Cylinder
« on: 02 February, 2017, 12:08:50 »
When launched at the 1955 Earls Court show, the BSA Dandy was advertised as using a chrome plated aluminium cylinder. Aluminium was needed to better dissipate the heat from the rear facing cylinder since cast iron has a much lower thermal conductivity. However, by the time it went into production in 1957, the accepted view was that the aluminium cylinder had been replaced by a cast iron one since BSA had failed to fully develop the aluminium chrome plating process by that time. Unfortunately, this change then led to cooling problems with the engine.

Intriguingly, I have Dandy engine DSE 365 which is fitted with a chrome plated aluminium cylinder. I'm not sure where the engine originally came from but it's engine number relates to a BSA Dandy produced in 1957 which seems to be at variance with the normally understood development history of the bike. It seems to suggest that the Dandy originally went into production with the chrome plated aluminium cylinder but was quickly changed to a cast iron one, presumably, due to premature wear of the chrome.

It would be good to hear from anyone with an early Dandy who might be able to shed further light on this issue or who has an engine with an aluminium cylinder?

Lightweights / BSA Beagle Rocker Feed
« on: 02 February, 2017, 07:47:54 »
Although the BSA Beagle 75cc engine looked like a small Triumph Tiger Cub engine, it was notorious in not being provided with a separate oil supply to the rocker boxes. This ultimately led to premature engine failures and the Beagle then being dropped from the BSA line up after just over a year of production.

One solution to the Beagle rocker box problem is to lubricate them by hand before each run out which is obviously less than ideal. I would be interested to know if anyone has implemented a better engineered solution to this problem which then makes the BSA Beagle a more practical bike to own.

Singles / Re: B25 Bottom end engineering recomendations
« on: 01 February, 2017, 18:49:16 »
There aren't too many people out there that offer engineering services for classic bikes. The best recommendation I can offer is to contact BSAOC's own Dave Smith (Rupert Ratio) who offers rebuilds on BSA unit singles. Normally, this is carried out on complete engines but I assume he might be willing to rebuild just the bottom end. He can be contacted through the club or via the following email quoting 'Ratio Rebuilds':

Singles / Re: B25 Bottom end engineering recomendations
« on: 01 February, 2017, 17:34:18 »
When you say bottom end refurb/rebuild, what exactly did you have in mind? Bottom end to me normally means everything below the cylinder. If so, are you going to do the top end reburb/rebuild yourself?

Which BSA do you ride? / Re: B40 1962
« on: 01 February, 2017, 13:25:43 »
Looks like a very nicely restored B40!

Pre War / Re: Pre war single - What is it?
« on: 31 January, 2017, 14:20:24 »
It looks like a B18 rather than a B35-2 going by the shape of the casting for the electrical generator behind the cylinder.


Some further thoughts:-

I seem to remember from your original post that the spindle appeared to be shifted to the left by about 3mm on both sides of the wheel? If so, then this seems to suggest that there is nothing wrong with the length of it - it's just wrongly positioned.

The spacer is of the order of 4 mm wide as you can tell from my picture. It would have to be 7 mm wide to be responsible for the problem you have.

It's difficult to get the position of the RH bearing wrong since it is constrained by a circlip on the LH side and by the locking ring on the RH side which should end up just below the end of hub tunnel when fully done up.

I would have thought the problem is most likely that the brake plate is not being forced fully on to the spindle and against the RH bearing. I had to rest the LH end of the spindle vertically against the bench and then use a suitable drift to drive the brake hub fully into position.

The simplest test is to take off the brake plate and then tap the LH end of the spindle to drive it against the RH bearing and to then measure how much spindle projects beyond the LH grease retainer. It should be 1 15/16" if my measurement is correct.

Which BSA do you ride? / Re: A10
« on: 30 January, 2017, 13:38:49 »
Mine was black when I bought it but it is now Nutley Blue!


My hub is fitted with sealed bearings and I left out any inner grease retainers. I know my spindle is the same part number as you quoted previously but I'll go and measure it's length for you shortly. It sounds as though the RH projection of your spindle is not the same as on mine?

Unfortunately, I don't have an accurate method of measuring the length of the spindle now that the hub is assembled. However, the spindle projects 1 11/16" from the outside face of the brake plate nut and projects 1 15/16" from the grease retainer on the LH side of the hub. What are your corresponding measurements?

Singles / Re: B40 WD gear ratio
« on: 30 January, 2017, 12:58:44 »

You're quite right about the values. Rupert Ratio gives 17T/49T for the B40WD which is clearly wrong. I have just checked the B40WD parts book and, as you indicate, this gives a 18T/52T combination. That's certainly the last time I rely on Rupert Ratio!!

Singles / Re: B40 WD gear ratio
« on: 30 January, 2017, 11:31:18 »
The WD engine has a wide ratio gear cluster to deal with off road use as standard and what ever change is made to the sprockets first will still be very low and gaps between the gears will still be wide. According to my calculations a 19 tooth gearbox sprocket will give a 6.18;1 top and first will be 18.2:1 which is still very low for road use but perhaps not for off road.
I believe top gear will be 5.83 (6.53 x 17 / 19) with a 19T gearbox sprocket. Using a 20T sprocket would make the B40WD top gear similar to that of a standard B40. However, you'd need a 23T sprocket to give the B40WD the same 1st gear as a B40.

Basically, the B40WD is not that good on the road - unfortunately, it's also not very good off road either!!

Which BSA do you ride? / My Lightweights
« on: 30 January, 2017, 09:14:25 »
I might as well start with my 2 x lightweight BSA's which were fully restored last year.

Singles / B40 WD gear ratio
« on: 30 January, 2017, 08:51:47 »
I've assumed I have to re-start the previous topic from the old forum to continue with the discussion?

I had a quick look at one of my B40WD's and, surprisingly, it is fitted with a 19T gearbox sprocket rather than the standard 17T. I am still restoring this bike and have not yet had a chance to ride it but assume the previous owner was happy with the much higher gear ratio. My other B40WD has standard gearing which is much too low for my liking and I will almost certainly change to an 18T gearbox sprocket to improve things slightly.

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