Drones Build- 1974 Commando

Mark F · Sep 14, 2011

drones76 said:
Onto the head. It was removed last night. A bit of carbon build up on the valves and the tops of the pistons. No visible or 'feelable' scoring in the cylinder walls. The pistons move freely. At this point on a 37 year old bike with 20k miles, is it advisable to keep going and remove the bottom half and/or split the cases to clean the sludge trap? Or should I get the top end in order and put it back together?

Can the carbon be cleaned off with steam? And can that be done to the top of the pistons with them in the jugs? From what I have read, steam is one of the best ways to get it clean.

Any other suggestions, hints or old wives tales will be appreciated.
Here are a couple of pictures:

Drone I am going through the same repairs as yourself. I have pulled the barrels off to check things out and found a cracked ring. I wouldn't have known that if i had not removed them. Everything looked fine with the pistons in. Also get someone to measure the bores for you that is familiar with Brit bike/cast iron barrels.
It will also make cleaning the pistons easier. To remove the barrels now is really no big deal and as mentioned you can check out the cam and followers. Commandos are pretty hard on cams and followers so worth while I reckon. Easier done now than later. :roll:

drones76 · Oct 21, 2011

I am in the process of replacing the layshaft bearing in situ. I found a local place with the SKF roller($30). I got the gearbox outer (thank you impact driver) and inner (custom tool needed for nuts- below) covers off. Getting the layshaft out was a bit of a bitch. Heat gun for two cycles and a lot of pulling. I need to get a puller to get the bearing off the shaft.
The gear teeth all look good and uniform. No signs of damage. I did however find some bits from a chewed bush (pic below). The bush that is damaged does not want to come out. Is there a trick to getting it out? The other one glides in and out.

I also got the head back the other day. It looks gorgeous. I have not taken any pics of it, yet. The guy charged me $100 to tear it down, check the specs, replace two new valves ( I paid $68 for those) and seat and lap everything in. He is a retired Nascar machinist and does the work at home. A good guy to know. Money well spent.

I also need to replace the fasteners for the outer covers. I have heard good and bad regarding stainless. Is there a list of the sizes of the ones need? I have a fastener place a few towns over that sells WW but they are not opened on the weekend so I may need to call the order in.

I need to replace the big electrical connector block under the tank. What is the recommended replacement for that? I believe the same connector is NLA and I am not sure that I want to put another one back in there. Should i just go with individual connectors? I have only come across one bad bullet that needs to be replaced but some of the connectors are bad.

Tires are on order. Avons.

I have decided not to remove the Jugs at this point. I am going to get the layshaft bearing in and button it up regarding the drive train and see how it goes.

I have not done anything with the clutch at this point. When I took the primary cover off everything was coated in oil and looking very clean. The most that I could do was pull the clutch cable to see if the spring plate moved and it did. Should I disassemble?

A deep socket with fairly thin walls was grinded even thinner to allow it to get into the tight crevices for several of the inner cover nuts. It is a 14mm. The 1/4 WW wrench measured about 13.7 mm. It was close enough. Those nuts just needed to be cracked and then they came off fairly easily.