Thanks for the input everyone, much appreciated.   I hadn't thought about the engine being tight.  It seems fairly free on the kick start but I'll certainly run the engine up as suggested to see if this helps.  The symptoms aren't typical of a slipping clutch where I would expected the engine to rev without much drive.  Instead it just fluffs/bogs down and dies.  The bike rolls OK in gear with the clutch pulled in which would seem to rule out an excessively dragging clutch.  But I'm desperate enough to grab all straws so will check this again.  The ignition marks I refer to are those on the rotor and static plate provided with the electronic ignition kit.  Ignition timing set up as previously described aligning the rotor mark with the 'A' mark on the stair plate.Picture attached.

Hi Dave.  I've only managed 4 miles over several 'trips'!! Bike is a bit of a bitsa.  Left the factoru=y in 1962 as a Star (according to g to frame and engine numbers).  By the time I got it a twin carb head and TLS front end with rev counter had been fitted. 

My A65 Lightning fires up from cold, comes off choke quickly and idles nicely and will rev up cleanly when blipping the throttle.  Once out on the road the engine does not seem to want to pull under load.  The best way to describe it is as if it is trying pull away in too high a gear.  The 'box selects correctly (on main stand with wheel free to rotate), new Wassell electronic ign system incl coil, leads and plugs.  Timing set statically to the A mark on the rotor with the piston at 34 degrees or 7.7343mm BTDC.  Checked using dial gauge through the plug hole and a timing disc with both readings corresponding. Valve clearances correct (new valves & seats), new liners and pistons (std bore) and new complete clutch assembly.  New carbs (u/sonically cleaned and blown through on the airline umpteen times). They have the blanking plug mod allowing the pilot screw bore to be blown through and checked as clear. Pilot screws set to 1 1/2 turns out, slides lift together and clear the bores, choke slides working correctly. In line fuel filters on each carb feed, new petrol tank and fresh petrol as well as new fuel taps.  Feels like a fueling issue to me and thought the tank vent may be blocked but have same problem when running the bike with the filler cap open. There's a new cam in there and the bottom end was built up by T&L Engineering with a re-conditioned crank. Fresh battery (Motobatt) and the circuit is charging reading 14.5 VDC across the terminals with the motor running.  As you can imagine I've run out of ideas as well as patience! My wallet's a little empty too!  Does anyone have any idea as to what I've missed or what could be causing the problems?  I would really like to get the bike running and get some miles on it this summer.  .

Thanks for the quick responses.  I'll take up the recommendations and try the tank clean/sealant route which will hopefully seal the tank dribble.  This should minimise potential paint damage and save future embarrassment of wet trousers!! Rob

Out on a ride recently I noticed a wet patch my trousers in the area of the inner thigh.  Mmmm. I'm sure that last rather tight right hander wasn't all that scary was it?  Then I noticed the distinct aroma of petrol!  The tank had developed a leak at the lower right corner.  Not enough for petrol to obviously drip but sufficient to wet the tank and hence the wet trouser problem!  Have drained the tank and inspected with an endoscope thingy and that corner does seem to have some corrosion but the rest of the inside is good solid steel.  I'm reluctant to bin the tank as it's otherwise sound. As it's not long been repainted I'd like to try and repair it with minimal damage to the paintwork. I'd thought of cleaning it out, treating with a proprietary de-rusting solution and then coating with something like flow liner.  Many years ago I had a similar leaky tank (Ducati Darmah) repaired by lead soldering which lasted at least 15 years, until I sold the bike (mistake!). Is lead soldering feasible as a DIY job? Any thoughts on how best to proceed?  Recommendations for de-rusting solutions/tank liners, contacts who could do the lead soldering or any alternative methods or advice would be gratefully appreciated.   By the way, I drained the tank out by syphoning.  Is it just me or does modern 'petrol' just not taste the same as the good old fashioned leaded stuff used to?  Perhaps a little more tonic with it?  Rob

That's a neat and simple idea...why didn't I think of it?  I'll make something up similar which means I can now put the £100 or so a stand may have cost back into the build. Thanks for that!!  Rob

Will hopefully be starting the build of my second A65 motor before too long and thought that an engine stand will make life a bit easier.  Have looked at a few on line but these seem to be limited to 30kg max weight, Sealey MES01 for example.  With the A65 motors weighing around 62kg when built up can anyone recommend a suitable stand?  Thanks.  Rob

Thanks everyone for the responses and advice.  Love the DRZ400 BSA, looks amazing.  I had a feeling this wasn't going to be a straight forward problem to resolve!! Thanks for the tip about the DVLA and trying to get a hybrid registered as I don't have a V5 for the frame.  If my pile of engine bits won't make a complete motor without some very serious financial outlay (I'm skint after the current project build!) and with Jap motors looking problematic I think I may need to look for a complete BSA motor and go from there.  All fun and games in the classic world, but that's why we do it isn't it?  Happy spannering.  Rob

Having completed the recent restoration of my 1962 A65 I'm now looking at the huge pile of parts that came with it to see if there's another viable bike there. Ive got  a decent tank, frame, wheel hubs but the biggest concern is the state of the various rusty/knackered engine parts. From recent experience it will cost a small fortune to build back into a reliable power unit. I had at first thought of giving up on the idea of a second build and selling everything on.  However, perhaps I could use a more modern engine and build up a hybrid as the next project.  I want to stick to a 650cc air-cooled, carburettor, vertical twin if at all possible. Initially looking at a more modern (i.e. oil tight, more powerful) lump. Yamaha XS650 or early Chenai Royal Enfield interceptor units?  Concerned about the fit, particularly the height as these are overhead cam, wet sump designs which are likely to be taller than a BSA unit.  Has anyone in the club been down a similar route in the past and could offer some guidance?  Or will I be banished for thinking such heretic thoughts???  Rob

 Agree that some heat and penetrating fluid should do the trick. You're a little luckier than I was.  On my project some previous numpty (as opposed to this one!!) had used wood screws to fasten in the gauze would you believe!!! Took hours to drill 'em out and repair the threads.

Thanks for the advice which I'll try when I'm next in the shed.  I suppose it's one of the fundamental laws of the universe - the ease of starting is inversely  proportional to the number of people watching!!

Have now completed the build of my A65. Originally a 1962 Star but at some point in its history fitted with a twin carb (Lightning) head.  Rebuild has been comprehensive, including electronic ignition.  With new carbs fitted and following the cold start sequence found here in the clubs posts it fires first kick from cold every time (really!!) then ticks over and revs nicely.  All good.  Only problem is I can't get it fire up with a warm/hot engine. With a warm engine it's fuel on, no choke, no tickling, part throttle, ignition on.  Take it just past TDC, a hefty swing. Nothing, no matter how many times I try.  Have tried many combinations of throttle/choke/tickling but no joy. Once the engine has cooled, starts first kick. Reluctant to take it out for a run in case it stalls and I can't start it again. Does anyone have a technique I can try or where I can buy some magic dust from?  Thanks. Rob

In response to Roy's comment about the change from 19" to 18" front wheel.  My A65 has the speedo drive running off the front wheel rather than the rear.  I also have a Honda (sorry!) on which I reduced the front wheel from 19" to 18".  The speedo here now runs 5mph high as a result, i.e. if it reads 35 speed is actually 30.  Calibrated this from the speed readout on a TomTom Rider410 satnav.  I assume that the BSA will also now read around 5mph faster.

Now the bike is running I have an issue with charging.  The stator that came with the bike had exposed wires as they entered the resin outer of the windings.  i.e.the insulation failed.  I tried to repair this but obviously didn't!!  With lights on the bike will run for about 30 mins before beginning to misfire as I limped home.  Electronic ignition systems don't tolerate low supply voltages as well as points do so I guess this was was the problem. Makes sense to me as the ammeter showed a continuous drain of about 4Amps and there's a 9 Ah battery fitted. Getting it going again the voltage at the battery isn't a steady 14Vdc but flickers on the multimeter reading so i suspect the output of the alternator is dodgy.  There is a new rectifier, regulator fitted.  So I'll need to buy a new stator. The original is a single phase item.  Would it be worth upgrading to the later 3 phase (with suitable rect/reg unit) or should I just stick with the single phase set up?  Are modern reg/rect generic for both permanent magnet and self exciting type rotors or do I need a type specific one?   Sorry, seem to have written an essay again!  Rob

Thanks for the starting tip.  As a BSA ( and Brit bike in general) newbie, starting the bike consistently has been something I haven't mastered yet.  Sure it will be now though !!