Just when you think you are getting close to the end of a build…Some of the details as I sort through an engine that was supposed to be ready to go, add a custom airbox, reassemble the painted bike, and get it all running.
The test rig. A test tank because the pipes have to be removed a few times during the engine break-in. The naked airbox can be seen tucked in there. Once the engine is tuned, and the outer airbox painted and mounted, It will be finished.
First of all, the bike is running. It starts easily, and was taken through six heat cycles, keeping the revs low. Once that was done, it was taken out on a ride to push it a little more. That produced head gasket leakage on all three cylinders. While disassembling the top end, a welding goober was found, apparently burned into the head. Since the sealing surfaces are a little rough, they will get a light resurface, new copper gaskets, and some high-heat silicone on reassembly. Other defects were a lock washer substituted for a sealing washer on one of the head bolts, and a broken piston ring. There was some debris washed down into the middle cylinder and sump that kept the crank from turning completely. Since new head gaskets, head bolt sealing washers, and exhaust gaskets are going in, some ignition points were also ordered. After a check, the ones in the engine are just in spec. When dealing with an unknown engine, it is best to check out the basic stuff. In this particular case, it may be a better idea to just start over on some of this.
After just a couple passes, it is obvious there is slight warpage and leakage by the tell-tale black burn marks. Not too bad for something fifty years old. The welding goober was knocked out with the tip of a three-sided scraper. There is a small divot seen in the lower burn mark.
After resurfacing, the divot is barely visible, and burn marks are gone. The other two heads were given the same treatment.
Amazingly,a Kawasaki S3 airbox was located in one of my parts bins. It was given to me in a load of other parts by a mechanic friend.
The box was cut apart, the mounting ears removed, and welded back together in a more compact configuration. Some mounting brackets and the stock rubber tubing then went on.
The top cover was hammered out in the shop along with the retainer bolt. The air filter element is a generic one.
A late idea added to the build (actually, the rest of the bike was already being painted at the time) was an airbox made from the original Norton oil tank and tool box. They were joined with the Kawasaki airbox made to fit inside, and the tail-end of the expansion chambers passing through a carved-out section on top. The unit may still be split down the middle after paint to make removal easier. The air filter can be changed by taking off the left side cover.
The left side cover was given a frenched-in place for the petcock, which was already passing through this spot.
The body parts lined up, waiting to get to their final spot.
The Lucas light shell and custom parts filling all the holes.
The front fender and bracket in place. Cosentino Engineering upgrades for Norton Roadholder shocks were used to give a more modern ride.
Tail view showing the brake light recess and exhaust pipe cut-out.
Achieving the flat’ straight body line on the seat and tank bottom was a little tricky on the Featherbed frame, requiring some elevation of both to overcome the dip in the center of the frame.
Too bad this lovely view will be obscured by the tank. The removable heat shield under the tank clears the center pipe by just a few millimeters.
More heat mitigation, some woven fiberglass insulation on the pipes under the seat.
Early on in reassembly, the straight tank-seat line can be seen here.
A box to hold a tiny lithium battery is tucked behind the engine. The fuse holder is seen on the side. The electrical system is completely functional. Now if we can only get the rest of the bike the same. As a side note, I was originally recruited for this project to build the seat. That of course led to designing the tank mounting/heat shield system and accompanying frame mods. The electrical system, plumbing, airbox, disassembly and final assembly, and most of all, engine start and tuning were mine by default, and not altogether expected. Not that I mind, as a good puzzle is always appealing to me, just a little out of the order I would have done things in, had I known.