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Messages - JulianS

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Twins / Re: Bsa valve seat depth
« on: 16 February, 2017, 18:10:43 »
I have had a number of seats replaced over the years and I was never asked that question, each time the engineer knew what to do and the  job was well done with no issues.

I thought that there was probably some engineering good/normal practice here when the new seats are fitted and cut?

Cut too deep you get poor gas flow and run out of tappet adjustment.

Not deep enough its possible  valves might touch piston with high comp piston and/or high lift cam or again you could run out of tappet adjustment.

The only figures I have seen are for fitted valve spring length.

I would consult a different engineer.

Twins / Re: A65 clutch thrust washer
« on: 16 February, 2017, 12:24:15 »
Yes that is the right way around.

Pre War / Re: Exhaust valve lifter
« on: 15 February, 2017, 20:57:02 »
Does this look photo look about right?

I think the part is the "tappet guide plate with bush" part 24 420 which was a common part for the 1926/27/28/29/30 engines.

I think its the 1926 engine in the photo which comes from Pitmans Book of BSA by Waysider 1930 edition.

The second photo is from the 1926 parts book.

Pre War / Re: Exhaust valve lifter
« on: 15 February, 2017, 19:57:49 »

Could you post a photo of the broken bit?

Pre War / Re: Replacing Sloper fork spring
« on: 14 February, 2017, 20:58:35 »
The photo is from The Book of the BSA by F J Camm, 1935 edition.

Not much information but hopefully it will point you in the right direction.

Twins / Re: A10 rocker cover banjo oil feed union bolts
« on: 14 February, 2017, 13:10:19 »
The twins had 2 the same 65 317.

65 318 was the one with larger feed hole which went on the exhaust rocker of the Gold Star single.

The Star and Garter / Re: Thread gauges
« on: 13 February, 2017, 20:40:55 »
Almost forgot - oil pipe petrol pipe and petrol tap threads are BSP thread.

The Star and Garter / Re: Thread gauges
« on: 13 February, 2017, 20:13:47 »
These are some of the common ones.

Lots of British standard cycle in 26 tpi up to 3/8 diameter and 26 tpi and 20 tpi over 3/8.

Some BSF - notably the cylinder head bolts  and crankshaft sludge trap. Lucas stuff usually BSF and BA.

Whitworth coarse usually for threads in alloy casings.

The pressure relief valve is unusual - it is 7/8 x 16tpi UNS (Unified National Special)

The thread on the speedo head cable connection is metric 12 mm x 1 mm pitch. ( Gearbox end is BSCy)

Pre War / Re: Colour code for BSA sloper maroon
« on: 13 February, 2017, 19:20:49 »
The photo is from the 1930 brochure and shows the available tank colours, which included a maroon option for an extra 1.

I thought that all the other painted parts were in black.

Twins / Re: Refurbish old brake plate
« on: 13 February, 2017, 13:22:06 »
The edges were polished alloy rather than chrome. They will polish up very nicely.

Twins / Re: Brake plate removal
« on: 13 February, 2017, 11:55:47 »
See the little pressed rectangle by the spoke in photo, there are a number of these around the edge of the coverplate, they just spring over edge of hub with some pressure.

To get it off I gently tap the edge of the plate from the brake side of the hub using an aluminium drift.

Some pattern cover plates use different indentations around the edge which still spring over and come off the same way.

Twins / Re: Brake plate removal
« on: 13 February, 2017, 11:19:35 »
It should just lift off once the nut is removed but there is probably a bit of muck or corrosion holding it.

Try moving the brake lever as you pull the plate.

If that does not move it then with nut removed the spindle will move inwards a bit so gently tap the brake plate end of spindle and it should free off. the circlip only holds the bearing cap and bearing in place and does not effect brake plate removal.

Photo shows cross section of the hubs.

Twins / Re: A10 Head id
« on: 12 February, 2017, 14:42:31 »
It is an A10 head as fitted from 1954 til 1959.

67 1066 is the number for the basic casting of the head. The head with fixed fittings (guides) is 67 1065.

Fairly common BSA numbering system - for instance the rev counter inner timing cover is casting number 42 0154 but the finished item is listed as 42 0153 and the alloy head casting number 67 1549 is part 67 1548 with fixed fittings.

Pre War / Re: Sloper brake problem
« on: 11 February, 2017, 13:39:29 »

I dont think they were linked front and rear.

You could specify either a foot operated front brake (left toes)  or a hand operated front brake or a front brake with hand and foot operation, with rear operated by right foot.

Photo from 1929 catalogue.

Twins / Re: A10 rocker cover
« on: 10 February, 2017, 19:21:56 »
After 40 odd years trying this still presents me with a challenge.

It is probably the worst job to do on a preunit twin.

I dont think there is a foolproof way and I disgarded my pushrod comb years ago as it was quite useless.

The first issue is the limited space between the top frame tube and head can make it difficult to engage the four holding down studs into the holes in the head. This is worst with the alloy head 650s with long studs. The top inlet inspection cover stud was originally made with machined flats to ease its removal to increase the space.

Having overcome that obstacle I favour the elastic band method to hold the rockers in position. I put a bit of grease on the lower end of pushrods to hold them in the cam follower.

With an alloy head I cover the holes shown in the photo with a bit of tape, just incase the nut is dropped whilst fitting it, it can be a bit of a fiddle getting it out.

Fitting the sleeve nuts on the alloy head can also be a bit of a fiddle, getting the threads on the nut to catch on the stud.

 Having positioned the gasket and applied your chosen sealant, lower the box onto head and guide the pushrods into the rocker arms using your fingers. Sometimes the pushrods will be caught on the front edge of the inlet joint. Having fitted the pushrods, probably after several attempts, and avoiding force insert the four long bolts and gently tighten a bit and add the other bolt and the four nuts. You may need to rotate the engine to allow easy tightening.

Having finally tightened all the fasteners you can set the valve clearances.

If using thick modern gaskets, which might come in blue or orange or yellow materials, expect them to settle after a little use needing the fixings being retightened and clearances to be reset.

Keeping the oil in can also be a challenge but that is another tale.

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