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Twins / Re: Plunger A7 clutch
« on: 19 June, 2017, 11:50:15 »
Since my last post, I have come across several used pressure plates and all barring one were dead flat, which is what we would expect. The odd one was dished exactly like my original two. I bought one of the flat ones and is now installed.

I drilled the six spotwelds through on one of the old ones to separate the two pieces and it is easy to see that the dishing of the flat plate occurred during the spot welding process during manufacture as the outer piece is not a dead flat surface, probably due to not being pressed to shape enough. The dished ones have probably given thousands of miles of service, once bedded to the outer friction plate.

One of the dished ones is not wasted - cut out the centre to allow for a socket and welded a bar to it, to lock the clutch centre when tightening the nut.

Twins / Re: Plunger A7 clutch
« on: 29 May, 2017, 22:05:52 »
Hi, Thank you for the advice, but I too have an A10 special with a 4-spring clutch which is good, but equally I currently have a B31 and have owned both another A10 and B33 that had the 6 spring clutch fitted. The later 6 spring clutch when set up correctly and fitted with parts that are not worn out or damaged, can be a perfectly good clutch too. It is my intention to do the same with my plunger A7, which to me looks a better design than the later clutch fitted to the S/A models which is the one I feel you are referring to, but I accept that experience may change my view on that.  I am also not sure that the 4 spring clutch can be made to fit the plunger models anyway.

This is why I need to find out whether the dished plate is a design feature or not, for interest if nothing else. If it is not correct I will buy new.

I also would also like views on the experience of others, what Surflex plates are like in a "dry" environment, as such inside the sealed clutch of plunger models.

Twins / Plunger A7 clutch
« on: 28 May, 2017, 21:44:22 »
On rebuilding my 1952 A7 clutch, I notice that if I put a straight edge across the friction surface of the outer pressure plate (67-3245), there is a pronounced "dish" ie it is not flat. The "dishing" is uniform across all diameters.  The difference is about 1mm at the inner diameter of the friction surface. I would not expect this, but on looking at a spare clutch that I have, it is exactly the same? Both correct or both wrong? All other plates are dead flat. Don`t want to buy new if that is how they are.

The outer plate is made up of a pressed spring plate, spot welded to what looks like a standard plain driven plate. Does the spot welding create this "dishing"? How/why would it need to be dished. Could easily be overlooked.

Whilst on the subject I am contemplating using "Surflex type friction plates, which in many applications are wet with oil, but not so in this type of BSA clutch if properly sealed. Do we still use the cover?   Appreciate informed thoughts on this.  Thanks.

Singles / Re: M33 1955 - Starting Issues
« on: 24 April, 2017, 21:45:10 »
With the bike on the centre stand, remove the sparking plug, put the bike into 2nd or 3rd, push on the rear tyre in the road direction and when you look at the contact breaker rotor, it will be turning clockwise. Operate the advance retard lever and check what you have to do to move the cam ring in the opposite (anti clockwise) direction. That will be the way to move the lever to full advance - opposite direction to achieve full retard. So now you will know whether you have a "tight" or "slack" cable advance. The other way to check is to look at the contact breaker and if the adv/ret cable is on the right of the CB, then it is a tight cable advance - on the left a slack cable advance. It would be nice if all were the same, but over the years swaps take place, incorrectly as Julian mentions. Extremely important information to know about your bike, both for starting and running.

Now push slowly on the tyre again, with a finger over the plug hole  and when you feel compression you know the engine is with the piston rising towards TDC awaiting a spark. Lets check this is happening at the right time? Using a thin rod of some sort, one end resting on top of the piston, SLOWLY continue moving the rear wheel until you reach the highest point the rod travels and mark the rod with some reference point to the outside of the engine. That is TDC. Once found carefully recheck and then with your adv/ret lever in the fully advanced position, turn the engine backwards a little to send the piston partway back down the bore. Once done, this time moving the engine slowly forwards again, mark the rod at the point the contact breaker JUST opens. Measure the gap between the two marks which should be in the order of 7/16 inch. If not the magneto needs re-timing correctly.

Twins / Re: Electronic ignition
« on: 16 April, 2017, 20:32:34 »
What is recommended for an A10 with the K2F magneto. I have always been happy with magnetos, but the one on my A10 is getting tired. I have a spare u/s magneto that I would be happy to convert to keep looks correct. The bike is already 12volt. Anybody have any experience doing that?

Singles / Re: M33 1955 - Starting Issues
« on: 03 April, 2017, 20:57:43 »
It is very easy when you have had these singles a long time and CAN start them, forget how b... difficult they can be when you first get one and need to master the art. So my reply is based upon the supposition that you may be new to this machine - apologies if not the case.
My method is set the advance/retard lever partially retarded, fuel tap on. While the carb is filling take the engine to compression and if one is fitted, use the de-compressor to ease the piston just over TDC. If bumping off, put the gearbox into second and pull the bike backwards until you meet compression resistance. Doing either of those will put the piston near the start of the power stroke and will, when set in motion allow 3 strokes or 1 1/2 revolutions before the piston meets compression again, when the kinetic energy stored in the flywheels will be enough to take it past TDC and hopefully fire and hopefully run. Now when that is done, I then give the carb a light "tickle", but not to the point of flooding. This raises the fuel level slightly above normal and will help the engine to "catch". With the throttle only slightly open give that kick, or bump start to set those flywheels in motion. All things being equal it should at least fire if not burst into life. Good luck!

« on: 29 March, 2017, 21:30:50 »
Thank you for your replies. What prompted my initial post is that I have a s/a A10 which is a bit of a special, fitted with WM2 rims and shod with 19X4.10 (100/90)  Avon Roadrunners front and rear. Although I have only done about 400 miles on these tyres, all seems to handle well with plenty of clearance where required, but having two tyres the same has come in for some banter! If the tyres are a bad fitment, I do have an economical way out, as I am coming to the end of a plunger A7 rebuild which is now needing tyres for its WM2 rims. Do I buy a pair of smaller profile tyres to use on the fronts of the two bikes and use the partially used Roadrunners on the rears?  What tyre pressures should I adopt?  Rightly or wrongly I usually put in 2 bar, just to ease the fading memory cells!  :-\ 

« on: 27 March, 2017, 21:29:02 »
Been having discussions/arguments recently regarding tyre fitments and pressures used on typical post war motorcycles and would welcome opinions from the forum. What is the point in having different tyres front and rear? A typical post war machine with 19 inch WM2 rims may often specify 3.00 front and say 3.50 rear. Why not have them both the same? Early A7 with Q/D hubs front and rear were intended to be interchanged. I can see that modern sports bikes need them different, but our relatively low powered classics - I am not so sure. Also early specification for tyre pressures, to me seem on the low side for modern tyre equivalents. Love to hear your views.

The Star and Garter / Re: Dating certificates & DVLA applications
« on: 22 March, 2017, 20:05:21 »
Back in 2004, I had restored/rebuilt an A10 which came to me with an old brown continuation logbook and all numbers checked out with the machine. However Steve Foden turned me down for support in retaining the number and  I emphasise this is not a criticism of him. It turned out that the frame had left the factory the year after the year stated on the logbook. Quite clearly a clerical error at the time of the continuation book, but my evidence was not sound enough and therefore I had to re apply for a dating certificate for an age related number. All this took several months and eventually I took the train with all the relevant documents to my then local DVLA to get the machine registered. I had also taken with me the old log book and to cut a long story short .... I was asked what was wrong with the registration  number on the old book :o! I was duly provided with my number plate authority for its original number! AND when the V5 arrived it had been left as a transferable registration. How times have changed. When I eventually sold the bike on, I left the number where I hope it will stay....and that is with the bike.  Finally Steve will have certain parameters that he can operate with and one of those will be the time he has available to do a pretty thankless task - well done Steve.   

Singles / Re: B31 Inlet Valve Rocker - oil drillings
« on: 20 March, 2017, 20:05:13 »
I can tell you with fresh embarrassing certainty, that the inlet rocker arm has only one oil drilling and that is at the push rod end. I know this, as I only today finished rebuilding my B31 cylinder head after a valve nipped up in its guide a couple of weeks back - inlet valve it was too! After years of trouble free use, I looked at all components carefully for a reason and noticed exactly what you have done, that there is only one drilling on the inlet side. I am guessing that being an inlet, there will be a tendency to suck oil down past the guide anyway, whereas the exhaust will have the opposite effect and hence the need for a little more oil. Early BSA twins did not have pressure feed to the rockers at all - relying upon mist feed! What caused my inlet valve to nip up (no damage by the way) after so much trouble free use, I believe to be pilot error :-[. When I got the bike back home and stripped, after the breakdown, I noticed that the advance /retard lever was not near fully advanced and that the engine had overheated after several miles of hard riding. The spark plug and exhaust valve were nearly white. No - normally it may be, but in this particular case it was not due to a weak fuel mixture. Malcolm.

« on: 20 February, 2017, 14:03:48 »
Thank you all for your replies. That article is a great asset Julian. I have printed that off for future reference. Oil the little pads seems the answer. Great.

« on: 19 February, 2017, 20:28:08 »
I have removed the bezel, glass and instrument mechanism, to allow me to do a proper job of re-painting the case, cleaning glass etc. I have no intention of any further dismantling as the speedometer seems to work fine, despite no motion over many years standing unused. Have members any thoughts about taking the opportunity of lubricating the mechanism while it is possible to do so? I had wondered about a light spray with WD40 allowing time to drain off before reassembly back into the case.

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