1970 BSA Lightning

Getting back into BSA’s
On my Hornet page I discussed some of the BSA’s I have had in the past. After purchasing my 1974 Norton Commando, a 1996 Triumph Trophy, and having two daughters, the BSA’s were let go. I had hoped to get another one at some point in time but it was on the back burner until a couple of years ago. A friend of mine who restores antique canoes is in a club of like minded individuals who are a close knit group.  When one of them died the deceased’s wife asked his friends to help him unload his canoe collection which was at a camp in upstate New York. While cleaning out the canoes he saw a couple of old motorcycles. He knew I had an old bike and sent me pictures of them to see if I would like to buy any of them. Although I was not planning to purchase a BSA I knew that if I did it would be a Lightning. After viewing his photos and seeing a BSA Lightning that was in pretty original shape I told him I was interested in it. I made an offer for it and an old BMW air head that was at the camp. When I arrived at the camp in New York, 628 miles away, I saw the bikes were in much better shape than anticipated. My offer was increased and I could only afford the BSA. I brought it home in the fall and got it up and running. The throttle cables were hanging by a strand or two and the slides on the carb were stuck from being over tightened. This is probably why it was put up 5 years or so before I purchased it. It had original tires, which were greatly out of round, and the gas in the tank smelled like varnish. Some squirrel lost his nuts when I started it up for the first time and they blew out the exhaust. I rode it a bit that fall, found out what was wrong with it, and then took it into the house to work on. Yes, in the house. Pictures of the bike as found and newly running are below.

The lightning was in the middle of this clutter. 

Dusty but in good shape. I was able to find the side covers and the original tool kit. 

The bikes were surrounded by antiques, model cars, toy trains, and snowmobiles. 

The BMW was in nice shape with its original tool kit and bags. 

Safe back home. It cleaned up pretty well and didn't take much to get it started. 

Getting it Running
The Lightning fired up without a lot of work. I started by draining the fuel and putting in new high octane unleaded. I add Marvel Mystery oil for top end lubrication, which is added to the gas cans when they are refilled. I have used this in all of my other old bikes too. While I had the tank drained I purchased new fuel tap corks. These are installed on pins that are a press fit into the shutoff valve. I found a post on another blog that suggested cutting the corks in half to install them instead of pressing out the pins. I used this method and it seems to work fine. One thing I learned was that the corks should be soaked in gas a day or two before putting them in and filling the tank. They will leak if you don’t follow this procedure. 

I changed all of the oil to make sure I didn’t do any damage when I started it up. I use Mobile One V-Twin oil which is rated 20-50 weight. I put full synthetic Valvoline 75-90 weight in the gear box and mobile 10-40 weight motorcycle oil in the primary case. To check the oil pump I took out the plugs, put the bike in 4th gear, and pushed it down the road while looking inside the filler cap. Oil pumped out, which told me it was alright to start it up. It had two different spark plugs in it. One was correct and one, which was probably borrowed from a snowmobile, was not.  I installed NGK plugs and then gave it a few kicks to get it going. It started 2nd kick which surprised me. After letting it warm up I took it for a ride around the neighborhood. One of the throttle cables broke on my initial run so I headed home. The second one broke after arriving in my driveway which put me out of commission. 

Working out the Bugs
I sent to Klemps’ for a set of throttle cables which arrived and were a little too short. I sent them back with my old cables and they returned cables of the correct length. I appreciated them taking the time to do this for me. Now I was up and running for the remainder of the season which was not to long as it was  September in Michigan.

My initial rides were very enjoyable. A few issues came to light right away. The tires were out of round, the clutch slipped a little, and it spark knocked pretty bad under load. I decided to tackle the spark knock first. I purchased a Tri-Sparks electronic ignition, which was easy to install, and it helped a bit. Next I tried Lucas octane booster without success. I started with the recommended amount and ended up with a 4 X dose. There was still no difference, although octane booster was dripping out of the tailpipe and sooting up the plugs. When I was working on the carburetors I found that they were set very rich. This was part of the issue of sooting up the plugs. I put the carburetor back to stock which was probably not the best thing to do for the spark knock. I found a local store that sold 110 Torco racing fuel. This cured my problem even after putting jets and timing back to stock. It was noticeably harder to start which was a problem I tackle in a later post. It also kicked back very hard bending the kick start lever, which I had to fix.  Racing fuel was also twice the cost of premium gas but it ran very well on it.  I put new tires on the bike, fork gaiters while I had it apart, rode it a bit and put it away for the winter. I purchased new fork seals but decided not to put them in since it was not leaking. I later regretted this.  I also had problems with the carburetor slides sticking. The carburetor bodies had been over tightened to the manifolds causing the binding. I backed off the torque and the problem disappeared.  

 In the house for the winter and ready to work on. 

Fixing the Clutch
The first winter I owned the Lightning I decided to take it in the house where it was warm for the winter. It gets too cold where I live to work on things in the garage. When it is warm enough, it is still not enjoyable. The lower level of my house has a family room which is no longer used as one. I put down a painters tarp and wheeled the bike in for the winter through a patio slider which entered the room.

My first course of action was to dig into the clutch. It had Barnett plates, which appeared to be new but were worn out on one third of the surface.  The metal plates were flat when I inspected them on a surface plate at work. It was leaking quite a bit of oil so I installed a new countershaft sprocket seal while I had it apart. I also replaced the clutch rubber buffers, springs, and bearings. When I put the clutch back together I put an indicator on it and spun it to make sure the plates were clamped flat. They were off by about an eighth of an inch. One of the screws that held the clutch together was shorter than the rest. This was probably the reason the clutch was slipping. I adjusted it properly and put it all back together.  I will put in a new clutch basket screw the next time it is apart.

Front Fork Rebuild
The following spring the Lightning ran fine and the clutch problems had been worked out. It still leaked a lot of oil around the countershaft sprocket which was probably coming from the crankcase vent I later found out. It does not leak as bad when the primary runs low on oil, which makes me think it is coming from there too. Maybe this is from the chain oiler? Does it have one? I did not think it did. A future project I guess. About midsummer the front fork seals started leaking. I decided to replace them at this time. This was uneventful. I have a service tool that works well to take off the seal holders. I made it years ago and patterned it after the factory tool pictured in my workshop manual. I had to heat the seal holders with a propane torch to get them loose. I was able to do this without damaging anything with the heat.

As previously mentioned I installed a Tri-Sparks ignition the fall I purchased the Lightning. It was easy to setup and the bike runs much better without the points. The only other electrical issues I had were the lights. They switch wiring was not correct and I did not have all positions on the headlight working properly. When I took the headlight apart I found a spare bulb from the previous owner. This must be a common place to carry a spare as I do the same thing on my Norton Commando. I sorted out the wiring by following the workshop manual and everything works like it should except for the oil pressure warning light. It is shorting out somewhere and I must get this fixed.

The original headlight bulb did not last long. The electrical contacts vibrated off of it. I replaced it with a halogen bulb which self destructed in about a week. It was a complete waste of money. The third bulb I put in has lasted and I am not sure why but I will go with it. I ended up fitting an LED bulb which is detailed on my main blog page. It has worked well and I am very happy with it. 

Another positive change was the addition of an LED tail light. I purchased this from British Cycle Supply. It is a bit expensive but it works great. It should reduce the risk of getting run over by cars and take less power to run. I put one on my Norton at the same time. The bulb kit requires the modification of the existing reflector. To avoid this I bought a reproduction tail light and modified it. This left my original one intact. 

Running on Premium Fuel
OK, so back to racing fuel, pump gas and fighting spark knock. My oldest daughter caught the antique motorcycle bug and has been riding with me for several years. She started out on a Yamaha TW200 as and has moved to the BSA. She rides the Norton too but prefers the Lightning. Our challenge with the BSA has been getting it tuned so she can start it on her own. She cannot kick it quite hard enough to start. It started very hard with racing fuel so I went on a mission to get it back to premium gas and make it start easier.

My first attempt was to retard the ignition about 3 degrees. It helped but spark knock was still pretty bad.  In the US we have ethanol added to our gas. This is a move being done to keep a certain political party and its constituency happy in my opinion. It is not good for old engines. The biggest problem I have found with ethanol is that it evaporates out of the carburetors leaving varnish build up much faster than regular gas. Frequent pilot jet blockage is the result. I have been using BP Ultimate (93 Oct) with Sta-Bil “Marine Formula Ethanol Treatment”  in my Norton and BSA to reduce the jet clogging and knocking (BSA) issues. It seems to be working well.

BP “Ultimate” did not totally stop spark knock in the BSA even with the ignition retarded. I decided to look at octane boosters. (Earlier lesson apparently not learned). I tried a 4x shot of Lucas again with no luck. Next I tried STP with poor results. I reverted back to the main jets that were in the bike when I purchased it and the spark knock on the top end was eliminated. Next I lifted the needle jet 2 grooves and all spark knock was eliminated. I may have the sooting issue that was prevalent when the bike was purchased. I will need to watch this for a while. Although it does not kick back anymore it still does not start as easily as I would like it to.

Next attempt........time for a de-coke. Alright, so this is one of the less glamorous parts of being an antique motorcycle enthusiast. I have been fighting pre-ignition problems on the BSA Lightning for a couple of seasons which I thought was fuel related. A local station started selling alcohol free premium which has worked well in my other bikes. I have not had issues with the Norton getting coked up, and I have had the head off several times chasing head gasket leaks, I decided to take a gander at what was inside of the BSA. Mid-winter Michigan, time on my hands, let’s take apart the head and see what we have. The Hornet runs great on factory timing and carb settings so the lightning should too…..right?

On its way to cleaner living.... 

Think I may have found the problem.....

Pistons ready to go.....




Now that everything is clean I will see how it run. The compression was at 150 psi on each cylinder last fall which is at factory spec. The timing and carbs are set to factory specs so let’s give it a whirl (when it is not 7 deg F outside).

July 2016 - Update 

The BSA was out in May and the de-coke test was on. All carburetor and ignition settings had been returned to factory specs and I was ready to go. I was feeling pretty good about myself and thought I had everything sorted fairly well. This was not the case. My first rides were not successful as the bike started to backfire after about 20 minutes as the battery was going dead. My five year old battery was tested and found to be bad. Problem solved or so I thought. A new battery just made the bike run longer before it backfired. A thorough sorting through the wiring found two frayed wires with one shorting on the frame. Problem solved again? Nope.

Stock 12 volt coils. Wiring a bit ratty. 

Bad coils? Research on the internet told me I should be running 6 volt coils with my electronic ignition and not the stock 12 volt coils. On with a set of old 6 volt Norton coils and the spark improved noticeably. I also added 5k ohm suppression caps with new copper core wires. Difficult starting cured. My daughter will be so happy! The battery drain was still not solved. After consulting with my electrical engineer at work and learning how rectifiers, diodes, and alternators work, I was ready to test. He even made me diagrams on how to do this. I will miss this guy when I retire and better learn what I can now. The rectifier was found to be bad ( or so I thought) so it was replaced with a transistor unit.

My wiring test diagram. Thanks Jason!

More on the electrical system. After all of the electrical work that was done on the BSA I was feeling pretty good about my recently acquired Lucas troubleshooting skills and thought I was good to go. After about 2 1/2 hours the battery started to drain down again and was at 10.5 volts when I made it home. The lights got dim and the horn did not work. I normally do not ride longer than this but wanted to learn how to put everything right. The last piece to look at was the alternator.

The clutch was also grabbing so I had a couple of reasons to pull apart the primary. There was a lot of oil in the plates which I cleaned before reassembly. Type F fluid was added this time instead of the 10/30 I have been using. This is popular with many BSA guys so I thought I would give it a try.

The culprit of my battery drain was found upon removing the alternator. One of the wires was cracked and not making contact all of the time. This explains why I was getting good and bad readings from my multi-meter out of the alternator and rectifier.

The new high output single phase unit from "The Bonneville Shop".

Uhhh....OK.....I will.......Thanks for the reminder. 

The hardest part...fishing wires through the case. 
A zip tie & the "push pull" method worked great...
...after 2 hours and internet research to figure it out. 

I purchased a new high output single phase Lucas alternator, 16 amp output, from "The Bonneville Shop" This was installed and the battery charging issue is fixed. Although the rectifier and Zener are probably good I replace them with a Podtronics unit which is rated to match the alternator. Trispark ignition, 6 volt coils, 5k Ohm suppression plugs, transistor unit with starting capacitor, and a high output alternator. I think I am now finally set to go. Time to take a few rides and test it out. I sure learned a lot on this foray.

Installed and ready to test.....the alternator and Type F fluid. 
Ok Lucas, I will trust you. Now its time to do you part. 

Update: I guess I was right to "Trust Lucas" as the new alternator works great. A steady 14.3 volts out of the Podtronics unit from idle to 3000 RPM. The LED headlight and tail light are significantly brighter which will keep me visible to cars and alive. A good investment in my view. The type F fluid is much thinner than the 10/30 I had been using and leaks from many joints on the primary case; screw holes, inspection caps, etc. I will tighten things down a bit and give the gaskets time to settle in. The clutch stopped grabbing for a bit but is sticky again. Time for new plates as the old ones are close to lower limits. The verdict is still out on the Type F at this point although I am not liking the oil leaks.

The carbs were replaced with a re-sleeved set and the bike runs considerably smoother all across the range  although there is still a bit of a stumble at high RPMs. I believe this is jetting and I will sort it out next spring.

The "missing" I was experiencing after the bike was out for an extended run was caused by a faulty Trispark module. Trispark sent me a new one for a great price even though it was long off warranty. I will remove all of the wiring and rework it this winter as the original harness is getting pretty rough. More to follow....

Winter 2016 update: 

For several years I have had a light tapping coming from my primary case which i have not been able to find. This year while changing clutch plates I discovered the steel center of  my Lucas rotor was loose. I replaced it with a like unit and hope I have fixed this issue. Sitting on the bench you cannot move the steel center, it is only when tightened on the machine that it moves. One more thing to put on my checklist for future inspections.

Yet more updates in my Blog.....





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