It's a funny old game innit

Having entrusted Siegfried's cylinder head work to Stu Rogers who has extensive experience of Norton open head hairspring motors it was astonishing to find myself standing next to one of these exact bikes whilst debating the Siegfried work. Upshot is that inlet valve guides are unobtainable although exhaust ones are. Stu has measured up the old guides and found them to be standard length, 45 mm and outside diameter, 14mm. The central bore is 9 mm which matches the valve stem diameters. However this should be 8mm for this sport model. Also the inlet guide should be shorter than the exhaust but these are the same length. After much discussion we agreed to say damn the torpedoes and go for 2 exhaust guides and see how that goes. Stu is concerned that we are repeating a previous blunder but lacking length measurement of the inlet we are stumped. At least we know it worked before even with a broken inlet valve. So new valves and 0,3mm oversize guides are on order.

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Norton hairspring valves

Here is the Norton version of Siegfried's head.

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Shiny painted toolbox + keys sorted out

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New headlight reflector fitted to Siegfried

The old reflector was rusty so it had to go. Here is the new one fitted. One of those jobs that look simple but which took a lot of time due to making old rubber seal and oddball retaining clip fit. Beam a bit yellowy, just waiting for new charger to arrive to plug into new on board connection.

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A tale of 2 tool rolls

Siegfried came with the black roll - velcro in 1958 ? Plus oddball contents. In keeping with the period is the proper type of roll complete with original, but now purely ornamental, Simson feeler gauge set‎. It'll be fun filling it with relevant tools / spares.

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Manx GP 2013

All set for 2013. Heysham overnight ferry out plus evening return plus homestay all booked. Following the disappointment of the Past Masters parade on the most interesting bikes screaming past in a bunch at racing speed I can't see the point of staying on until the Wednesday for that so will return on Monday evening.

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Siegfried electrics tidied up

Painted the inside of the battery box then added a trickle charger connector so that when Siegfried is parked up I can open the side box up and plug straight in. All due to being shown a neat crimp that feeds 2 stripped wires into 1 connector. Great + electrics work ok, so far so good.

Also boxes of new shiny parts arrived today from Germany. Complete new exhaust system with all connectors and silencer. Wow looks great. Mmmm....silencer bracket not in same place as old one but, methinks the hefty bracket to which the old silencer was attached with a non standard clip may turn out to be a handily placed sidecar bracket‎. We shall see.

Also today the new headlight reflector arrived, relieved to see it has the requisite slot to attach the bulb unit.

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In for a penny.....

As tends to happen with bike refurbs today was decision day. Having gone so far with new carb, new full exhaust and a host of other small but costly parts it was decision time on what to do about the worn exhaust valve. A rummage online led me to Stu Rogers in Wisbech. After an hilarious phone conversation rambling into all sorts of things the decision was made. The whole head was couriered to him today to work his magic. It is a relief as I was loath to end up butchering such rare and hard to replace parts. He has decades of classic bike experience plus mountains of parts and full machining facilities so best let him do the job. I can now finish off loads of small but significant stuff so that when the head returns it will be fun to bolt on all the shiny new goodies and finish the job.

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Siegfried's piston before and after

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Bent exhaust pushrod

Now I understand why the bike came with alloy rods and a note to say they could be turned to size. The pushrods do not match. Inlet is a hefty steel lump exhaust is alloy but bent!

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More tell tale signs

‎The rocker box cover above the exhaust valve has plenty of oil on it, to the bottom of the image, but above the inlet it is clear. Close examination shows 4 sets of tiny holes under the valves. My idea is that these are oilways to the valvegear. Looks to me that oil is going past the exhaust valve, some burning off to produce the sooty spark plug and some blowing back up into the rocker box. More turning over of the motor produced more oily sludge on the exhaust valve stem so it looks like the head has to come off for new valves and guides.

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Rich running - the guilty party at last

With a complete new exhaust system on order I found a C spanner and took the exhaust pipe off from the cylinder head. Peering inside the port with a torch I could immediately see oil running down the exhaust valve stem. Taking the rocker cover off revealed about 2mm oil swimming around the base of the hairpin valve springs. With the spark plug out and turning the motor over with the kick start produced more oil on the stem. Talk about trust your instincts. My first thought on the rich running issue was worn valves / guides and it looks like it is. A strange twist is that the seller included a pair of engineering grade rods and a note that these could be machined into new push rods. I wondered why ? The thought now crosses my mind that the only place that oil can enter the rocker box is via the push rod tunnel - are the rods the wrong diameter or worn thus letting too much oil through? Either way the head is going to have to come off now.

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Siegfried's speedo

Speedo could not work as the drive connector was not attached and had rusted into the rubber grommet in the head lamp hole. A quick blast with freeze spray and it moved into the clock first time. Locking nut now loctited and connecter zip tie secured. The clock may well be dead but at least I'll find out this way.

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Siegfried new carb installation complete at last

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Siegfried airbox intake grill tidied up

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Siegfried's new carb

The holes in the carb manifold did not line up with the studs in the head. One of these had been replaced, was too long and did not have the thread properly finished to accept a nut. As I hate nuts and bolts I extracted both studs, reamed out the manifold holes with a 10mm drill and offered up the carb complete with correct gaskets and lovely stainless Allen bolts.

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