Second restoration of the motor 30.09.2001  

(The motor has been removed from the frame)

(The motor is ready for inspection)

(just some spare mudguards)

(Ohhh. were should I begin)

(Ill start from the top - removing the cylinder head).

(When removing the cylinder barrel, remember to mark each pushrod, for correct assembly - and before lifting off the barrel, place pistons at lowest point).

(- And remember to mark the front of the cylinder barrel, since its reversible).

(When barrel removed, mark the valves, for correct assembly - Check barrels).

(Remove the pistons by removing the circlips, and slide the gudgeon pin out)

Next is the timing chain etc. Start by removing the generator.

(Remove timing cover, and inspect for wear) 

(Remove tension blade - inspect for wear).

(Open the timing chain - if possible, and remove is. Use a general purpose extraction tool to remove the timing gears from the cam shafts - its now possible to observe if there is any tear on the main shaft bronze bush)

(Remove the magnet - BTH in this case)

(Now flip the motor on to the side, and remove the crank case sump cover, to reveal the oil pump. Remove the oil pump)

(Unscrew the bolts that holds the crank case together - remember the 2 at the top in the cylinder barrel entrance, and pull them gently apart. Remove the cam shafts and the crank shaft).

(Inspect the crank shafts timing side with a finger nail, and check the driving side roller barring - Removing of the roller barring is done with a special extraction tool, which I am very fortunate to have (-: )

(remove the outside of the roller barring of the crank case, by gently heating the barring part and surrounding metal with at flame torch - When heated, get some ice cubes and place them in 1 or 2 plastic bags and rub them against the inside of the barring - With a little help, the barring is easily extracted)

(The timing side barring is extracted by applying pure pressure or gently punching it with a plastic hammer)

(When finished, store the parts a safe place - and still preserve order)

(Comparison of old bronze barring with original barring)

Close to assembly of motor

A new barring is made from correct lead-bronze, and is line bored in the crank case. 

(the line bored bronze bush)

(the surface is fixed)

(The bronze and the white metal bush)

(a fresh new white metal main shaft bush - just in case)

(the old and the new)

(the missing gaskets, ready for assembly)

Checking the shim distance - should be about 0.002 - 0.004 in. 

(Getting the correct shims for the crank shaft)

( Removing the roller barring for shim placement ) 

(Placing the shim )

(Mounting the conrods)

(Making the parts necessary for assembly, warm up to a normal temperature - not funny when the fingers stick to the crank case because of frost - preparing for assembly)

(Make sure to oil up the bushes - this is the last chance before actual run)

(Clean surfaces with a grease dissolvent, and wait for it to vaporize)

(Place the fluid gasket on the surfaces)

( Place the camshafts and crankshaft, and make sure that the cams are places correctly)

(Uhhh yes, I love it when I get to this stage)

(Oil pump is checked and assembled)

(Oil pump mounted on crankcase)

(Oil pump connector rod is oiled and inserted)

At this point I can hardly turn the crank shaft !!! I discover a line on the crank shaft, that was not previously there - Something is wrong. 

It turns out that the new screws that I bought from Draganfly, for mounting the oil pump is slightly longer than the ones originally used, so a slight modification was made for this screw.

(The difference in length ) (The tip of the screw, that touched the cranks shaft flywheel)

(The crankcase sump cover was modified, to make it more flat )

(A normal gasket was fabricated, and fluid gasket was applied - The sump filter gauze was inserted)

(Completing the oil sump cover assembly)

(Placing the gears)

(Chain + chain tentioner)

(Oil pressure ball + Spring) VERY IMPORTANT

(Make sure the gears are timed correctly)

(Now its time for the Cylinder + Cylinder head, but lets first place it on the motor stand, for ease and comfort.)

(Collection all the necessary components for assembly)

(Preparing the cylinder block)

(Fitting the pistons - Inserting the G-rings)

(Fitting cylinder block)

Cylinder head and tubes are fitted. Can be useful to have someone guiding the pushrods into the Cylinder head.

(Now its time for ignition timing, This is no easy business!! - But you wouldn't imagine what 2 bad CDs and some double sided tape would do)

Actual breaking point measurement was done by letting a small current go through the dynamo. The wires were connected to each side of the breaker, and a Amp meter was connected in series with the power supply. This way it was easy to monitor when the the breaking points went apart. (it can be done simpler with a small light bulb, and observe the dimming of the light, as the breaking points go apart)

Do not use large currents, since this will damage the dynamo. I used something in the order of 100 mA. But the larger the currents, the bigger the difference in open/closed reading.

(Place wires on nonmoving parts if possible, and if dynamo turned repeatedly, remember to take wires of and unwind them)

The manual says that: ....... Braking points should break at 4-8 Degrees After Top Dead Center....... In Advanced position, this should produce a 30 Degrees Before Top Dead Center. - If a mismatch should occur between these 2 figures, then go for the 30 Degree part.

But the trouble is, that I made some measurement data, which gave the following results:

A discussion was made on the [AOMCC] groups, and I concluded that the 30 Degrees Before Top Dead Center were the to go for. This was the opinion of everyone. The course of the timing problem, can - as far as I believe - only be the Auto advance unit, since this is the only variable in the system. If this was not the case, then the fault would have to be a change in the ratio between the exhaust camshaft gear and the Auto advance unit (not likely). 

(This is the Auto Advance unit for the BTH Dynamo - this is the one removed from my motor).

(This unit is the one fitted on Lucas Dynamos - These Lucas and BTH Auto Advance units are supposed to be interchangeable - pictures are from Markus Nikot & Leo Wood - thanks)

I have been offered a brand new BTH unit from Victor Horley. The unit is mounted when I get it home.

  (Since this is a 1950 Twin, and does not have modified cam form, which came in 1952, I have to set the valve-tappet cold clearances to 0.002 in at both the exhaust and Inlet. I modified my CD disc, now it can measure relative to both TDC and BDC).

(The valve covers are fitted - at this point the motor is ways 45 kg without generator and timing cover, and im assembling this motor at 1. floor - will it survive the way down the stairs!!)

I am a member of the "Danish Ariel Club" (www.arielklubben.dk), and "Ariel  Owners MC Club", Back to start page HOME - Get your Ariel things here www.draganfly.co.uk. 

Email me at - kimfmx@gmail.com