Removing Gearbox Outer Cover

The gearbox outer cover is on the right side of the bike and has mechanism for the kick starter and the clutch cable termination point.

The cover is retained by 5, fillister head, slotted machine screws. Since these screws most likely haven't been removed for 35 years, it wasn't surprising that 3 were frozen. Two came free with a lot of pressure on the end of the screw driver and slow even application of torque turning the screw, the other 3 were stuck. Besides being slotted head screws and recessed the screws seemed to be of a fairly soft metal as using a drift on one to try and break the binding free resulted in the slot on one screw closing slightly. Fortunately I was able to get the screw drive blade back into the slot. A combination of lots of heat and sacrificing a chuckable flat bladed driver to fit in the screws slot and then hammering it, they came free.

Not surprisingly a bit of water leaked out the bottom before the gear lube spilled out when the cover was removed.

Gearbox Inner Cover

Gearbox Outer Cover

Rust on the Clutch Operating Lever

Metal filings in the bottom of the gearbox outer cover

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Of concern is the sizable amount of metal filings in the outer cover. It has me wondering what I'll find when I open the gearbox itself.

Stuck Piston

The piston is still stuck after repeated attempts to free it. The present plan is to disassemble the motor and split the cases, then unbolt the connecting rod and free the cylinder. Then I can attempt to fee the piston without damaging anything but the piston and cylinder. A foreseeable problem is that the studs that secure the cylinder to the cases do not clear the cylinder even when the cylinder is raised as much as the con rod length allows. That's a tomorrow problem. 

Of Valves and Stuck Pistons

Disassembled the valve train today and it came apart quite easily. I feared that the valves in the left cylinder would be frozen like the piston but they fell out without much effort.

The valve seat doesn't appear in bad shape and neither does the valve.

Now the frozen left piston is another matter. This past Wednesday I filled the cylinder with PB Blaster and let it sit till Friday afternoon, hoping it would free the piston. No such luck. So I tried it again and left the PB Blaster in till this morning. Repeatedly beating on the piston top with a 5lb hammer with first a block of wood cushioning (hoping to save the piston) and then a hardened steel drift pin had no effect but denting the piston top.

Evapo-Rust was suggested as a possible solvent to release the piston, but that requires the ambient temperature be 65 degrees, which my garage won't be on its own till June. Fired up the torpedo heater to warm the place up and filled the cylinder with Evapo-Rust and left it sit for 5 hours, and... The piston is still stuck in place. But the solvent did loosen much of the surface rust on the cylinder wall.

Earlier I had removed all the nuts and bolts retaining the cylinder to the crank case and raised the cylinder about 3/4" off the crank case, which shows that the crank will turn freely.

Not sure where to go with the piston. One thought is remove the crankcase and cylinder from the frame, which I'll be doing anyway, and then splitting the crank case and unbolting connecting rod.

Jim

Cylinder and Pistons

The needed tools to disassemble the cylinder head have been acquired and this will take place in the next couple of days. In the meantime, I've been trying to remove the cylinder from the crank case.

The left piston is rust-welded to the cylinder wall. Wednesday I filled the that cylinder with PB Blaster, hoping that it would free the piston. No such luck. I have removed the retaining nuts and bolts and freed the cylinder from the crank case and elevated it about an inch, where it is now supported by blocks and wedges. I spent about an hour today bang away at the piston with a 5lb mallet cushioned with a block of wood, but to no avail the piston is still stuck. Next I'm going to try an air chisel fitted with a drift pin to see if that can break the hold of the rust.

Lifting the cylinder off the crank case shows that at least the crank shaft will turn and that is not rusted solid.

I've been able to determine that I'm the 4th owner of this bike, recently I tracked down the original owner hoping he would take a bit of time to answer a few questions about the bike.

Readers familiar with Norton Commandos will not right away that the frame has been heavily modified to approximate the design of the legendary Norton Featherbed frame. Commenters at the AccessNorton forum expressed concern that about its rigidity, so this was a primary question that I had. The friend who I bought the Norton from, mentioned that the engine had been modified and I was curious as to if any light could be shed on the nature of the modifications.

The original owner and the person who completed the modifications is the owner of a well known manufacturer of motorcycle accessories. He told me that the frame works well and was stiffer than the stock Commando frame. He also gave me an overview of the motor.

It has been bored out to 906cc, the head ported and polished with big valves installed. The whole thing was balanced and blueprinted and built with light weight pistons and valve train. His recollection is that the motor was producing about 90hp and 75 ft/lb of torque when he had the bike.

Jim

Cylinder Head Off!

My how time fly's. Heat and the hand impact wrench persuaded the stubborn number one head bolt to release.

As you can see water gained access to the left cylinder with the result being rust and mold. Had a friend who does a restorations take a look at the head and his thoughts that it will clean up just fine, but he'd like to take a look at the valve seats.

Note the spark plug tip in the picture below, it was frozen in.

The left cylinder and piston do not look promising, but I expected to replace the cylinder body and pistons.

Valve caps and rocker covers are off in preparation for removing the valve gear. These areas appear to be clean and properly oily.

Note that the lower threads of the spark plug pictured below are filled with aluminum. Something else to be addressed.

Now to locate a valve spring compressing tool that will fit into this head.

Jim

Cylinder Head Removal

Beginning to disassemble the engine. A previous owner had converted the motor to a single carb with the intake manifold appearing that it could have been fabricated by the builder. This manifold is held on by 3 Allen screws. What is interesting is that in both the shop manual and the parts exploded view, 4 bolt holes are shown attaching the intake manifolds for dual carbs. Don't know if 3 was a production variation or if the builder filled the inner pair and then drilled and tapped a single center bolt.

The Allen bolts retaining the manifold easily came out, though the center one required that I cut down an Allen wrench, ruining 3 hack saw blades in the process.

The bolts and nuts securing the cylinder head came off easy enough, except #1 in the tightening sequence. In the picture below, the bolt head on the right.

 

 Most of the fasteners showed evidence that lock-tight or similar was used on assembly and I suspect for #1 that this is also the case. Due to the location it is difficult to get heat on to the position in the cylinder where the bolt is threaded. I'm more afraid of stripping the bolt head than breaking it off. I'll try it again tomorrow with more heat and a hand impact tool, but I need to get the proper size impact socket.

Jim

Progress

The revival had stalled a combination of household projects, the winter of 2015 and frankly waning interest. Prior to the project coming to a halt, I'd built a bench upon which to set the bike, so I could work on it from a comfortable standing height. 

What got me enthused about the revival once again was a dollop of guilt, the chance to view the successfully completed projects of others and the rediscovery of the joy of bombing around on a roadster.

For a week I had the use of an RnineT, a wonderful, smile inducing machine and began thinking, I'd like to have one. But knowing that permission wouldn't be forth coming and forgiveness doubtful, I returned to the revival to scratch my roadster itch.

Today's project was to remove the cylinder head and begin the process of determining the condition of the engine. But immediately a problem appeared. Trixie had been converted from twin carbs to a single Amal with a custom fabricated intake manual, held on by 3 Allen screws. Getting the middle one out will require cutting down an Allen key to fit under the arch.

Difficult to reach Allen screw

 A previous owner had modified the frame in the manner of a Feather Bed Frame by removing the center tube and replacing it with a pair of frame members that runs along the base of the tank and a steering head reinforcement bar that also provides a mounting point for the coils.

Modified frame section with fabricated steering head reinforcement.

Also part of the frame modification was the inclusion of a third Isolator mount in place of the Head Steady. This is mounted to the reinforcement bar and mounted to the cylinder head using the same mounting points as the Head Steady.

Added Isolator