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Messages - AWJDThumper

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Singles / Re: C15 speedometer
« on: 15 February, 2017, 07:24:56 »
Tim. It might be possible to save the speedo but you would need to lever off and replace the old bezel to get at the internals. It's likely a bearing has seized and will need to be freed off and re-lubricated - I've had a similar problem before. In principle, it's an MOT failure but it's something they don't test for!

The Star and Garter / Re: Thread gauges
« on: 14 February, 2017, 12:14:17 »
I want to order a set of thread gauges to use on my 1958 BSA.
What threads are used on BSA's ?
You can get combined metric and imperial thread gauges - you only need one set of imperial gauges because they can be used whatever the thread form, ie BSF, BSW, BSP, UNF, UNC, ANS, etc

Twins / Re: A65 Lightning respray
« on: 13 February, 2017, 12:41:51 »
Marque Restore based in Coventry can do the re-chroming and I think they also have someone available who can remove dents and do the painting. However, it won't be cheap - possibly, 250 for the chroming and 250 for the painting.

Singles / Re: B31 crankshaft/ cushdrive woes
« on: 12 February, 2017, 09:27:43 »

I've looked high and low to identify the thread but the best I can find is that it might have been an obsolete American Standard thread which were all superseded by Unified threads during WW2. Nowadays, the closest you can get appears to be 11/16-20 or 11/16-24.

In principle, it would be possible to cut the thread on a screw cutting lathe - I think the thread size is just about big enough to get the cutting tool in. However, as Julian says, the issue would then be the correct grade of steel to be used and whether it could be easily machined. SRM do a replacement cush drive nut which is made from hardened steel but I'm not sure what a conventional cush drive nut is made from without seeing one. If it's made from hardened steel then it would be much more difficult to modify it.

Singles / Re: C15 Head Gasket Advice
« on: 11 February, 2017, 11:43:45 »
Just found this 47 thou thick C15 gasket advertised, albeit in the US. If the standard one is normally 40 thou thick, one like this might solve your problem.

Singles / Re: C15 Head Gasket Advice
« on: 11 February, 2017, 11:24:20 »

It does sound as though you head has been skimmed too far - I think 1 thou of gasket compression is going to be too low and I'm sure would cause problems. I think 5 thou would be the minimum required. My old C15 gasket is about 38 thou and a new one might be a little thicker but still not thick enough.

The simplest solution might be to get 4 thou skimmed off the top of cylinder liner - this will increase the compression ratio by a small amount but shouldn't be too significant. The alternate solution would be to get a bespoke copper head gasket made of the correct thickness, if possible - there are a lot of companies that advertise this service.

Singles / Re: Wiring loom / harness
« on: 11 February, 2017, 10:48:18 »
I bought a new wiring loom for a c15 which just does not seem to be right.
I ordered a loom with 12 volt spec so I could up grade from 6v to 12v.
can anyone recommend someone who can make a correct loom .
In what way does the 12V loom not appear to be right? If you don't have a wiring diagram for the 12V conversion, it's probably best to start off by comparing the loom against the wiring diagram for a standard 6V system to determine what has been modified. The main mod is to add a Zener diode for 12V and to re-arrange the wiring from the alternator. However, there may be some other mods done involving the elimination of some of the wires used in the 6V system. I would mod the 6V wiring diagram to reflect your 12V loom at which point it should be possible to determine what is wrong, if anything.

Lightweights / Re: BSA Beagle Rocker Feed
« on: 04 February, 2017, 11:48:11 »
My knowledge of pre-war motorcycle engines is practically nil but I'm very surprised that they relied on 'oil mist' lubrication for the rockers. However, the Beagle engine was effectively derived from that of the Tiger Cub/Terrier and they used a proper oil supply to the rockers. Had 'oil mist' lubrication been effective for this type of small engine, the Tiger Cub/Terrier would have used it I would have thought!

Lightweights / Re: BSA Dandy Aluminium Cylinder
« on: 04 February, 2017, 11:39:01 »
Thanks Andy but my Dandy has a good engine and I bought this spare engine with an Ally cylinder purely for historical interest. One of the limitations with the early engines, such as my spare, is that there was no easy way to top up the grease that the crankshaft ran in, short of taking the whole engine apart. BSA modified later engines to provide a means of pumping in new grease via an external grease nipple.

Singles / Re: B31 crankshaft/ cushdrive woes
« on: 04 February, 2017, 08:04:40 »

As said, the dia and pitch doesn't seem to match any obvious thread form. I assume this is a B31 crankshaft as its part number would suggest - but have you checked the diameter of the journals and it's fit inside the crankcases?

If it was me, I would probably take an existing cush drive nut, re-sleeve it, and then cut the appropriate thread to match that on the crankshaft. This would have to be done using a screw cutting lathe as a suitable tap wouldn't be available.

Singles / Re: B31 crankshaft/ cushdrive woes
« on: 03 February, 2017, 17:15:46 »
It looks as though the 1953+ B31's used cush drive nut 42-71 which has a 3/4 x 20 tpi thread. However, earlier B31's used cush nut 65-2520 but, unfortunately, I can't seem to find what thread this used. It's possible this used a 11/16 thread?  It seems most B31 crankshafts were stamped 66-610 but do you know what year the engine is dated or is it just a box of bits?

Lightweights / Re: BSA Beagle Rocker Feed
« on: 03 February, 2017, 07:30:31 »
Here's a picture of the Beagle exhaust rocker box in which you can see the small hole in the rocker exposing the spindle underneath. The only way of lubricating the spindle as it stands is by dripping oil into this oil which would be very difficult because the spindle is not far off being vertical. Also, you can't flood the inside of the rocker box with oil because there's a relatively large hole down to the crankcase caused by the pushrod tunnel which would drain it very quickly.

Edward Turner's scheme was that oil mist generated in the bottom of the engine by the rotating crankshaft would find its way up the pushrod tunnel and then find its way on to the rocker spindle to lubricate it. I don't think that was ever going to happen!!

Lightweights / Re: BSA Beagle Rocker Feed
« on: 02 February, 2017, 23:20:33 »
If I remember correctly, there are small oval cut outs in the top of the rockers through which an oil mist might have come close to lubricating the rocker spindles. I think your suggestion is definitely one up on taking off the rocker covers off before each ride out and pouring in a bit of oil. However, the positioning of the inlet to each rocker box would have to be carefully chosen as the oil would need to drip on to the holes in the middle of the rockers since that's the only way to get oil on to the spindles. This would seem to mean the inlets being in the rocker covers themselves although the inclination of the front rocker box would be a bit challenging.

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!

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