Rust bustin'

I started with the rear plates from the clutch basket. They appeared as bad as all the other plates.

 

The photo below shows the plates after about 10 seconds. the white in the water is the gas from the reaction, so the power supply was working really well.

After about an hour I removed the clutch washer (as rusty as the securing nut, and it was in really good condition). The black marks indicate where the red oxidisation was.

The rings took about as long and came out well too. there is little pitting so the damage is cosmetic. The rear drive plate is too badly damaged. I will have to examine to ensure it is the same dimensions as all the others - there are quite a few sets available on the net in great condition.

Rust removal set up

There's plenty of posts and information on electrolysis rust removal, so I'm just going to cover my set up briefly.

After using this for restoring old hand planes, I know that the smaller the bucket, the quicker the results.  The electrolyte is washing soda, using about half a cup to around 5 litres.

My positive anode is my old file, works perfectly here as it reaches the full depth of the bucket.  For the negative current, I bought single strand electric wire (90c/metre) and stripped the insulation as required.

Finally the power supply. Previously I have used a battery charger, with OK results. I am aiming for 12 volts and 4 amps. I found this transformer for under $30 at Jaycar Electronics. It is 240V AC to 12V DC @ 5 Amps - perfect. It is designed to supply 12V fridges, so should run for a while. I removed the plug end and fitted alligator clips.  Now to put it to work.

Clutch basket removal

After removing the clutch cover (6 blots and springs) I had to remove the basket. This wasn't too difficult - I used an oil filter wrench to hold it steady while I undid the nut.

After that I used a puller working against two of the clutch cover nuts hand tightened back on. Then it was time to inspect the damage. 

The back of the basket was pretty good; just a little rust on two of the springs and one of the rivets. I've got a plan to deal with that later.

The back of the inner basket looks worse, but most of the "rust" is grotty oil left over from the sump. There is some alloy corosion, but it is literally surface defects only. 

Flip it over and its another story.  Below is one of the clutch plates adn a drive plate. They are badly rusted and pitted. A new set of clutch plates is easy to get hold of but a little worried about the drive plates. These plates stack alternately in the basket.

The very rear of the clutch basket has one final drive plate with two spring/shims behind and these three plates are secured with a really fine wire in a tiny groove at the base of the castlations.

 

I am pretty confident about getting all the plates replaced, but these rear springs are a problem. Next step is rust removal...

Removed the barrels

I thought the saga of the front barrel was goignt o be a major headache. Fortunately, after another couple of days of penetrating oil I managed to get the piston to move slightly more than half an inch from the top of the cylinder. After that it moved quite easily until it got to the bottom inch.

I was already concerned about belting the top of the piston while the barrel was supported on timber (to protect the mating surfaces). After sleeping on it overnight, I though about one of those pilot type problem solving exercises. For those that remember Apollo13, Gene Krantz turns the problem on its head and asks what right? Well I then thought if the piston was at TDC, then hitting the barrel from underneath might be kinder. It worked well, in fact the barrel hardly needed much to move it and I could get away with hitting on the fin area.

So next move is stripping the engine accessories so I can split the crankcase and deal with the rusty guts!

Removing the cylinder barrels

After removing the rear cylinder head, I decided to press on with the cylinder barrel. Having played around before I knew the front piston was pretty stuck but having loosened the barrel bolts I could at least rotate the engine by hand. Doing this the entire front barrel was moving up and down the studs.

Cylinder cleaned up massively but not going any further!

There was significant carbon and a bit of rust in the liner, so I used the penetrating oil again over a couple of days. Unfortunately this was still not working, so I tried my trusty orange persuader. Hitting on the cylinder with the barrel supported by timber got some movement. I was hoping to get the piston far enough down the barrel liner to remove the piston wrist pin. It just wasn't happening and I was concerned about the hammering causing damage to other engine components.

I changed my attention to the rear cylinder. By this stage, I know I am going to have to hone the liners at a minimum, so removing the barrel completely from the piston is no concern. The barrel came off easily and is in pretty good condition. Unfortunately what I found next was not...

Peering into the crankcase, I was pretty surprised to find rust, and a lot of it. In reality, I am hopeful that the fact that the conrods are still attached, that all the bearing surfaces are OK (fingers crossed). It also explains why there appeared to be a smattering of rusty deposits throughout the engine - I suspect that it has been sitting around exposed and possibly then turned over so the oil system has distributed the rust infected oil around the motor.

Still have to figure out how to remove the front cylinder barrel. I will think this one over before attacking again. Full engine rebuild now confirmed!

Spare cylinder head

I have the original engine, which will hopefully be handy for parts as I go. My concern, though is that the engine is seized - possibly a front cam seizure, a known problem for this motor. The head came of fairly easily; I needed a couple of days of penetrating oil to loosen up the bolts.

Once off, sure enough both valves were stuck partially open, indicating binding of some kind. I couldn't rotate the cam, so went with plan B, which was to pull the cam until it rotated.

I used a bike spanner and cam sprocket bolt as a puller. after about 5mm movement it all freed up. The valves closed and the cam and bearing came out pretty easily.The exhaust side was pretty badly damaged, the cam surface, follower and tappet end all had significant pitting. The inlet side was OK. I will remove the valves to check the condition, but the head also has some witness marks around the cam bearing, which makes it not as sound as the other.

Front cylinder head continued

With the tappets removed, the valves were the last parts to come out. The valve spring compressor was the right size, but the tappet port is offset, which meant that the compressor started to infringe the cylinder head before the spring was fully compressed. By adding a 23mm socket to the top gave me enough clearance to get the job done.

 

 I labelled all the parts to allow reassembly on the same side as they came out, once I have checked the tolerances. The valve spring lengths seem OK, but their lean angle looks a bit more than the 2mm limit.  I cleaned up the valves avoiding the mounting face (I will lap these later to remove the very minor pitting and scratches). The valves sit in the guides well, only very slight wiggle.

I worked my way around the head cleaning up the surfaces. The inlet port I filed level and cleaned out the 6mm thread. I also cleaned out the exhaust flange - it was full of old gasket. The 8mm studs took some work to clean up due to rust.

Next was to see how easy the painted finish was to remove. I bought some heavy duty paint striping gel and had at it. Being a gel it has 24 hour working time, so I worked over it about 5 times. 

Pretty happy with the result but quite a bit of wire brush work was required on the cylinder dome (with the valves in place to protect the seats). Putting this one aside for now as I am thinking about soda blast to strip it back - I will do that once I know how much I might need to do over the whole engine.