g3l exhaust

[r wheat]

Hi removing a very rusty exhaust from a ww2 g3l, which was untouched for many years, a short piece of pipe remained in the head, is this normal, does this piece screw in the head or is this held in another way. many thanks Richard

[clive]

The piece you refer to is probably a projection from the cylinderhead. I think the iron heads had this projection from 1949 to 51 (not sure how it was originally fitted in the head. I would avoid trying to remove it. This was also the period when the valve springs changed to the hairpin format). If buying a new exhaust pipe the important dimension will be the internal diameter which will fit over the projection.
I have bought at a jumble a new pipe which was made of thinner guage pipe than the original and consequently did not fit.

[Rob Harknett]

Ashampoo_Snap_2017.08.02_21h34m03s_002_.png

Ashampoo_Snap_2017.08.02_21h32m33s_001_.png

Prewar machines had the exhaust spigot, G3L did not, 1949 the spigot appears again. See attachments.
This only refers to a couple of parts lists, so when the spigot was phased out, then re introduced, I have not checked.
You should be able to tell if your head has a spigot or a bit of exhaust stuck in. Perhaps scape it to see if its cast iron or tin. If it is a spigot, take care they are very brittle and easily break. A PO may have stuck a bit of tin in the port, to act as a spigot, to accept an exhaust system, of approx. 1/8 larger dia. Such a bodge may have been common, if the approx. 1/8" smaller dia system was not available. ( Note I say system, as both pipe and silencer have to match the dia. I guess post war you could had used that bodge of bit of pipe in a 350, to fit the larger dia. 500 exhaust system. Which may be other reason, if your 350 has got a bit of smaller dia. pipe stuck in it. Years ago flexi pipe was also available to make such bodges on the cheap. I used felxi pipe on an old prewar AJS back in the 50's. An old silencer was available, so the felxi pipe, was packed with a bit a Bake bean tin and clamped on. I thought that was great then, as my AJS was a twin port, but the left hand port was blocked off, by a bit of tin bent over the spigot and clamped on.

[clive]

the two parts list illustrations show the difference between the two types of cylinder head which may help you to work out what you have, the shape of the rockerbox is quite different. .

[Rob Harknett]

I never took much notice of the different heads Clive, eyes fixed on the port. You may also find a part number cast on the head, the first two digits of an old part no. being the year of introduction. The part may have been used other years. Some prewar heads have the number under the port.
Your comment about an exhaust pipe made of thinner material Clive, leads me to think, some of the people that ask how do you seal the pipes in the head, may have a dodgy pipe. Loose as it has a smaller dia.

[r wheat]

Hi lads thanks for all replies. I will check but I believe the head has 9 fins like the one in the pictures that has no tube out of the exhaust port, tomorrow I will try and scrape the part as suggested. This may well be a bodge as I know this bike spent a lot of its life on a island off Scotland so spares may have been hard to get, the rusty exhaust was a over the foot rest type. cheers Richard

[Rob Harknett]

If it is a bit of pipe stuck in the exhaust pipe, you may see where it ends, If the head should have a pipe in it, there should be a lip acting as a stop, for the pipe to push up to. You will see on the head with the spoggot, the stop is external.

[r wheat]

Hi the piece of pipe is cast and appears to be part of the head, I have tried upload photos of engine showing number and head, but must be doing some thing wrong HELP cheers Richard

[r wheat]

Hi with help think I will try to post the rest cheers Richard

[Rob Harknett]

There will be a lot of history for this bike that would be impossible to discover. It is very unlikely it still has a high % of parts it had, when made. Look at the engine no. 41/SU/G3L3725? plus other stampings. Also there was at some time an ID plate riveted over the number stamped. The first mystery is, the engine number is not in any WO contact. Numbers end with 28799 and restart at 400000 for W0 contracts. Within this gap there are two contacts , for 142 and 500 machines. The gap in frame numbers only seems to account for this amount of engines. So that leaves 2944 engine numbers un accounted for. We can only guess, at this time bikes were needed, material and parts in short supply. So anything would be used to put a machine together. The G3 engine then was more or less an AJS engine, but with the mag at the back. Early war time parts lists show, prewar AJS parts were being used, like barrels and heads. I cannot read the part number cast on the barrel of your engine. I would not worry about the mixture of parts that make up your bike. WD bikes are like that. They may even have some very odd parts, fitted during the war and post war. They may had been captured by Germans , Italians etc rebuilt, re-stamped etc. etc. then re-captured. After the war re-built and sold off. Bikes and bits left behind in various countries, taken by locals and rebuilt to make a bike.
The SU stamping I have never seen before. SF suffix for a part would refer to silver finish. Perhaps a WD expert has done research and discovered what SU refers to. Maybe you will find a cast part number on the head that will explain something. Look under the port or on the top fin area between the push rod tubes.
The engine may had started life with that head, or it may be a post war head fitted in the early 50's, when bikes were reconditioned and sold off.