|
BSA C15
BSA C15
My Bike
Technical
Restoration
Links
Other
My Bikes
BSA
|
|
C15 pre-65 Engine Rebuild |
General
|
| Crankshaft & cases
The crankcases have been cleaned down and degreased. Remember to oil the bearings and steel parts afterwards or rust will set in. The old gasket material was removed prior to countersinking the bolt holes and then I removed any high spots on the mating faces. Check the threads in the crankcases, it is a good idea to run a tap down them and clean out the bottom of the 1/4" BSC holes with a 4.5mm or 3/16" drill. Any rectification work on the threads needs doing before you put the cases together. I have had to heli-coil 4 holes as the previous builder was a little heavy handed. The crankshaft is an early 1960 model with a plain bush big-end bearing, which was not running true, so this was rectified before it went back into the cases. Blue Hematite was used on the jointing faces and the bolts torqued down to 10FT/LB.
Click on the photo's for a better view Having fitted the oil pump, I put a small rectangular magnet into the sump plate to collect any bits of ferrous particles in the oil. You should be able to buy one from your dealer. I used one out of a magnetic cupboard door catch. |
| Camshaft
As the old camshaft was pitted on the cam lobes, I purchased a second-hand one in good condition, which cost £18-00. Always fit new tab-washers as they do not cost a lot. The cam followers go back in the same positions that they came out of and then camshaft. The timing marks are lined up as noted when stripping down.
Before fitting the inner timing cover, I have had to drill and tap the gearchange cam cover securing bolts out to 1/4" BSC as these had been stripped previously. The bolts needed their heads reducing and chamfering, so that they did not interfere with the fit of the timing cover.
Before fitting the cover, measure the depth of the holes and make sure you have the right screws to fit. Click on the photo's for a better view |
| Gearbox
The gearbox assembly was fitted into the bearings after they had been oiled, and the gearchange selector and camplate located in place, prior to a trial fitting of the case. This allowed the gear change to be tested and I also took the time to check the case screws and select the correct lengths required. I used Solvite Silicon Instant Gasket to make up for the poor mating surfaces.
Check that the oil drain hole is clear before assembly and do not forget the distributor clamp, which goes in screwed end forward and the screwed half inner-most.
Be careful not to drop the split pin into the gearbox when fitting the gear-cam locating pin. Click on the photo's for a better view |
| Timing Side
Having fitted the cover, a small pin should be located in the camshaft before the location washer (shown below) is fitted. If you do not have this pin, one can be made from an old bicycle spoke. A new lock washer should then be used and the nut tightened down. (I used 35ft lbs)
Click on the photo's for a better view |
| Clutch
A new cup for the clutch actuating arm has been made, and instead of the flimsy 9/32" dia I have made it 3/8" dia. This can be seen in the assembly.
As the old clutch pushrod was damaged and I could not get hold of a new one, I have used one for a Villiers engine. This is 3/16" shorter so I have saw it into two and placed a 3/16" ball bearing in the middle. This not only works a treat, but reduces the binding effect that can be the consequence of a bent pushrod.
The Clutch cush drive housing has been cleaned up ready for the insertion of the rubber dampers. Click on the photo's for a better view |
| Alternator Coil
The wires on my coil are in a poor state, having broken at the connectors and the insulation gone hard. As this is an old type with open coils, it is possible to solder on new wires. Because I have converted this bike to 12v, I only need to fit two wires in place of the old three. Click on the photo's for a better view |
| Distributor
On turning the rotor, I notice that there was a click on each rotation and that the shaft would only rotate freely in one direction. This was caused by one of the pegs on the advance retard mechanism catching on the underside of the condenser. A little bit of relocation on the condenser and problem solved. I have also put a new wire onto the terminal to connect to the harness. A new rubber oil seal is required as the old one is completely perished.
Click on the photo's for a better view |
| Primary Drive Side
The clutch and primary drive chain have been assembled and it is now time to think about the chain tensioner. All of the newer models were fitted with one, but there are still some like mine that did not have one. This can be retro-fitted and you can purchase one from TMS at Nottingham.
Job done, and now it is time to fit the alternator back into the assembly. Click on the photo's for a better view |
| Cylinder Barrel, head and piston.
The piston was cleaned up and I then polished the crown prior to re-installing it. This helps to prevent the carbon build up.
I noticed that the piston was 0.020" oversize.
The rocker cover stud that was missing has been replaced and the hole has been heli-coiled to suit. New hollow dowels have been made, as the originals were missing and I could not buy new ones.
The valves were removed and I found that there was a black oily deposit in the exhaust port. Close examination shows wear on the exhaust valve stem, but the guides seem reasonable, so a new valve is my first step. The head was cleaned, being careful not to scratch the combustion chamber. The new valve was then ground in and the head reassembled.
Click on the photo's for a better view |
Ignition Timing The timing is set by rotating the crank to Top-Dead-Centre (TDC) on the compression stroke, (both valves closed), and I then used a dial-indicator gauge to measure the 9/32" (7.1mm), but you could fix a pointer to one of the studs and use a steel rule. Rotate the crank back past the distance and then forward to the 9/32" mark. Now with the distributor cam rotated to fully advanced, rotate the distributor body until the points begin to open. I used a battery and bulb to indicate this.
Click on the photo's for a better view |
|
Pushrod Tube The pushrod tube was rusty, so I have stripped it and Nickel plated it, while at the same time I did the studs for the barrel/head to weather proof them. Click on the photo's for a better view |
| Oil Filter
I have decided to fit an oil filter in the return line from the engine to the oil tank. After all the time and effort, it seems little to pay to protect the engine internals.
|
