Saturday, January 14, 2017

'70 BSA Lightning Maintenance & Upgrades

I enjoy riding the BSA and it has made many trips around my area since I purchased it in 2009. It has run with minimal issues, and aside from routine maintenance, has not required much attention. This changed last summer when it started acting up leaving a few things in need of repair this winter. There have also been a few enhancements I have wanted to make for a while. Here we go......

 A new tire in place and being balanced with my "Marc Parnes" wheel balance tool.  

The clutch plates were at their lower wear limits which I discovered last summer. New EMGO cork plates have been installed to replace the Barnett plates which hook up good but do not let go after the bike has been sitting for a day or two. Breaking them loose is a pain. Using EMGO plates was a Hornet modification and a tip from an old BSA dealer in Hobart Indiana. To keep the primary from weeping oil I went back to 30W. I know I will  never get it leak free but I will make it "leak freer".  There was no final drive chain oilier hole to be found in the Lightning primary which I thought may also have been causing leakage.

Darn....forgot to loosen the counter-shaft and primary nuts before taking the rear wheel off. Lesson learned again. Reassemble to disassemble ........

An easy way to pull the clutch plates.....a mechanics magnet. 

Repacking the bearing and fitting a new basket nail. Someone had put one short one in which made adjusting the run-out more difficult than it needed to be.  

I have had a mystery knock coming from my primary for a long time and I finally found it. The center in the rotor was loose. This was discovered when I tightened down the primary crankshaft sprocket. The center will not move when on the bench but does so on the  bike. Luckily I had an extra one on the shelf I could use. It is installed and tightened down with no issue detected. I will need to reset the timing since I do not know how the last rotor was lined up when it was set. 

My "Mystery Knock"....the offender....a loose rotor center. 

All back together and checking run out. The indicator is overkill but works fine. 

The brass clutch nut lock tabs (right) were worn off and had to be replaced with new steel ones. This is easy to overlook but the tabs must engage with the spring ends to keep the clutch from coming apart. The clutch springs were stiff creating heavy lever efforts. They were replace with lighter duty springs improving the lever pull significantly. 

A 21 tooth sprocket replacing the 20T. This should be good for a 500 RPM drop at secondary road speeds and make a more enjoyable highway rider. 

The next fix was to repair the cracks that have been working their way back on my headlight and up the rear fender. After dis-assembling the fender I found a much larger crack that was almost across its entire width. It was not very easy to see so I welded and painted it.

My vintage plate also suffering a terrible fate. 

The fender tip crack welded, painted, and disguised with a sticker. The other crack ran full width and was also painted. Luckily it is under the tail light & not too visible.

The chrome paint looks more like aluminum. Although I did not expect a perfect match I thought it would be a bit closer. I will try something different next time.

The registration plate gets an aluminum backer. Let's see how this works. 

The steering head has had a hitch in it for a while. When I blocked the front wheel off the ground and removed the steering damper it was plain to see that the bearings and  cups were damaged. The SRM roller bearing upgrade on my Hornet is silky smooth and I decided to go the same route with the Lightning. This was a pretty uneventful upgrade, just a lot of stuff to take off and reassemble. One area that needed adjusting was the stack up of the bearings as the steering lock rubbed lightly when assembled with the roller bearings.
The SRM Kit ready to go.

Out with the old......hard grease, damaged bearings & cups. 

In with the new......SRM tapered roller bearings. 

A .035 shim added to increase the stack up. This was done to stop the steering lock from rubbing on the frame. I used a fork nut washer which I bored out to 1.125. 

New bearings in the triple tree....

Back together. Time to finish the wiring. 

Nothing to do with this post but just plain cool! The original decal - Parson's Auto & Cycle Supply.

While I am eager to get the BSA back on the road and try my improvements it is 20 deg f outside and it will have to wait. Time to finish the wiring upgrades I started before Christmas.

Not very good bike riding weather here....nice for taking photos. 

Another side I support my antique motorcycle restoration habit....the Product Development department I work in built the interior for our Company's 2017 NAIAS vehicle....check out the link.


  1. A trick for the license Plate is to use a plumbing washer (hard rubber or soft plastic material) on each side of it next to the flat washers and bolts/nuts.

  2. Thanks for the tip John. I will give it a try. I found a loose head steady bolt that may have contributed to my vibration issue and am checking all of the engine mounts too. Although I routinely check bolts to make sure they are not loose I do not usually put a wrench on them to check. I think I need to start doing this once in a while.