BSA A70L Lightning - Second Test Ride - Not Without Problems
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- čas přidán 9. 09. 2024
- At last the decent weather has returned so we can go out for another longer test on the A70 following the tank lining/repair. How does it go? Starts off well but gradually deteriorates ........
In the summer of 1971 in what is now Silicon Valley, my father bought a new candy garnet brown Honda CB 750 K1. I was 13 at the time and our next door neighbor bought a new BSA 650 Lightning.The man down the street already had a '69 BSA Rocket 3. They all would go riding on the many sunshiney days in California. No traffic, just lots of enjoyment. I always rode on the back and remember a simple and wonderful time. Beautiful music from 3 excellent machines...
Great anecdote Frank - thanks for sharing.
It didn't sound like 'pinking' to my ear, more like rocker-box-internals or even loose valve-stem. Superb-looking-machine though , beautiful restoration . I gave-up my many British-bikes years-ago , now ride an-almost bog-standard Kawasaki W650 and an 82 Yam TR1 with a retro-make-over . They sound great, look-great and only need the-usual 'consumables'. Too-old, too-far-out in 'The-sticks' and ride too-hard to risk old-bikes these-days, but I would if I lived in-town . Dave NZ
Hi Dave and thanks for the interest and kind comment. This was a while ago now and you’re right it wasn’t pinking but I won’t spoil the thunder if you’re watching the subsequent videos. The Kwacker W sounds like a great compromise bearing in mind where you live. Was in NZ last Jan - beautiful country both north and south and thoroughly enjoyed. Cheers.
Hi,it does sound like pinking,pre ignition, ....you could have a decompression plate under the cylinders ,this reduces comp ratio,thus reducing pinking etc.
Hi Matt - thanks - something to consider if simpler remedial options don’t resolve the problem.
Angus, if I owned this the first thing would be to get the head off and measure the combustion chambers. If one valve seat has sunk only 20 thou the volumes would be uneven .They have to be exact . Then I'd measure the piston heights to guarantee even compression .They have to be identical .I might even do a full cylinder volume check (pistons at BDC ). You could have slightly mismatched pistons.With the head off I'd change the exhaust valves and get new later modern spec seats pressed in . Then balance the chamber volumes.Otherwise you could be chasing shadows for the next six months. Throw away the points and fit a modern electronic system . It s a ton of work and cost but you want the job right . Jonny Peace ,
Hi Jonny - all good steps to consider in due course - thanks as always. Let's start simple with the sparks and juice, as the major items in the restoration were undertaken by reputable engineers - crank ground and balanced at SRM where they stated the original NOS AE pistons were the same weight within tolerances, also barrels lined and bored at Wards engineering Rugby where they are meticulous. Agreed I haven't changed the valve seats; however, they didn't appear to be sunk and I did cut them as well as grind in - acknowledged that this may have slightly altered volume. I do use premium unleaded which with some brands in the UK is still ethanol free. Yes I do run points but these are the later models with each set capable of being timed independently. Appreciate all the suggestions Jonny and you're obviously very much more skilled and experienced than I am so you've given me plenty to consider and pursue - thanks for the interest and information.
@@BSAPowerSet I'm sure you'll fix it -you got the right attitude . Unless there's a problem raised its easy to assemble a well engineered engine badly-- by that I mean omit doing specific checks along the way such as cylinder volumes, combustion chamber sizes, cam lobe matching ,piston heights ,rod lengths and so on .There's every reason to believe its all within tolerance yet every reason to suspect it's not .Engineering firms do specific jobs-- its up to the engine builder to assemble those bits with a questioning mind . I worked at Devimead in the 70's and learnt so much-especially how poorly made some BSA late engines can be .and just how to build a good one . Peace Jonny
Cheers Jonny appreciate where and how you gained all your knowledge - respect.
I have some ideas if that's a ping if so and you're interested give me a heads up. Looking at the spark plugs will tell you a lot.
@@BSAPowerSet Have you checked the ignition cam mechanism for run out . ? Take the plugs out and in gear turn the engine over using the back wheel with a DTI on the cam .Not the best design as the taper drive can be damaged easil;yby heavy handed work .
I had a conversation with an old school brit biker and he advised to run in with a richer mixture and slightly retarded timing settings from standard, mainly due to the lower running in speeds not cooling sufficiently, thought I'd mention it in case none of the books mention this kind of street wise knowledge.
Many thanks for the suggestions. This has moved on since this video; however I do run it slightly rich and have since re-timed. Thanks again and for the interest.
I think you're on the right track. I had an A65 engine and the timing had to be spot on or it knocked. Good luck.
Thanks Dennis. Hopefully we’ll all find out soon enough.
The motors new, New Motors tend to run a little bit hotter because of the extra friction the parts aren't broke in 2. possible cause of ping if the spark plug extends too far into the cylinder head or does not match up perfectly with the edge of the cylinder head on the inside that can cause a hotspot either the edge of the head around the whole or the spark plug sticking too far into the chamber. also a 1 range too hot spark plug can cause the Ping, lean mixtures burn hotter than Rich fixtures another possibility. Spark timing can be retarted a little to help cool it until the parts are warn in.
Thanks Thomas for the info and pointers - appreciated.
such a shame ...but i know you will get it sorted m8 😜👍
Indeed I shall Mick - no probs. It's still in one piece - which it wasn't when I bought it!
Beautiful looking bike Angus, Well done ! What fuel have you used ?
Many thanks. I use premium unleaded. Currently checking timing and backing that off a little from standard before thinking about additives if necessary.
The sound quality did not allow an accurate diagnosis but if it was me I would ensure the fuel flow to the carbs is OK, ie not restricted due to the tank coating as my initial reaction was pinking, turning the engine off while riding and checking plug colour would determine any mixture problem, but I would lift the head to check the top end anyway. You could increase the octane by using Millers Octane Booster, I swear by it in my 60's / 70's bikes.The risk of oil on the rear tyre would worry me too. Very best of luck.
Thanks Paul - tips and thoughts appreciated as always.
What tyres did you get for the A70 🤔🏁💨
Hi Keith - I've put TT100s on it which I prefer.
Just curious, but are you going to apply the fake leather stick on strip on the tank? Hopefully just needs backing off a bit.
Hi - a very good question as a while ago I was investigating whether that black trim was originally applied to '71 season models, or whether that was an addition for '72. Anyone know the answer? It doesn't appear to be shown in the '71 parts book, unlike the tank pinstripes which have a separate part number. Anyhow no I won't be applying it either way as I don't think it suits the dove grey framed colour scheme. Thanks for interest and comment.
@@BSAPowerSet My A65 export is a June 71 build and has the black strip Also the timing may have moved on one of the cylinders, very unlikely to be a small end.
Thanks. So yours would have had black frame originally. Yea timing may have slipped on RH pot - or I just didn’t get it right in the first place.
Yes, black frame with dove grey rear shocks
Ah yes you may have told me before thx.
Are there any race tracks near enough where you could purchase some high octane fuel?
Hi Jim - nice thought - Santa Pod not too far away lol - I can get 98 octane locally so that should do with the timing back of a couple of degrees. Will publish a vid shortly with further tune up work - promising results prior to another road test. Thanks for interest.
Hi if the colour of your is Etruscan Bronze please could you give the colour code for the Etruscan Bronze paint. I'm in the process of restoring my dads' BSA Thunderbolt 1972, just joined the BSA owners club and was told the tank was Etruscan Bronze. Thank you
Hi Tina - thanks for the interest and comment. Yes it is Etruscan Bronze although a little darker than most I think. I don’t have the RAL code I’m afraid as it was matched by a local company no, longer in business, from a side panel I have in original factory paint. So apologies I can’t help, although RS paints can provide the colour online. The 72 thunderbolt was indeed painted in that colour as a solid one colour - there were no white panels on the tank. Thanks again.
Thank you for your quick reply it was a great help
Do you have a picture of the colour so we can get a match please?
Hi Tina I can’t attach an image; however have a look through the videos in the A70 restoration playlist as there is one video that focussed upon the tank and side panels when I was attaching the transfers.
You need to stop running the engine and bottom out that rattle, sounds serious to me
Hi and thanks for the interest and comment. This has moved on since that test; however, yes a number of issues have been diagnosed and addressed as per subsequent videos. It’s not been plain sailing!
@@BSAPowerSet Back in the day I had an A50 Royal Star, a Thunderbolt and a Spitfire with GP carbs, I was a mad bugger back then and I tuned the engines as best I could and rode the bikes hard against the bikes of my pals. I got good at rebuilding the engines and fault finding, for example I managed to repair a broken inlet valve outer spring by the side of the road whilst touring in Scotland using just the standard tool kit supplied with the Royal Star, the broken outer spring jammed up and bent the pushrod too but I managed to straighten it all out and carry on with just the inner spring controlling the valve and obviously keeping the rpm down managing to get home ok without further incident. Your rattle if it's just pre-ignition sounds odd and doesn't really fit with my experience as being due to just over advanced ignition timing although timing might be partly to blame, what I think is that your fuel was partly or mainly to blame as I've had a similar issue when brake fluid was drawn into the engine via a faulty brake booster servo working off the intake manifold vacuum on a race car I was preparing, I wonder if the product you used to seal the tank had some unanticipated effect on the fuel on it's first use after it's application, perhaps the tank should have been flushed before use.
@@rotax636nut5 Thanks for all the info and anecdotes - I always enjoy reading these and suggestions based upon knowledge ad experience. I won’t go into details but suffice to say that it wasn’t just preignition on the A70 and subsequently the head was off! Thanks again for the interest and participation.