Exhaust nut test

Made a new sample nut from high grade aluminium. My intention is to make a final version as soon as I get new, suitable insers for making inner thread (managed to damage the only one I got). Otherwise I will have to use this one and maybe make a somewhat larger dimension hole for the exhaust tube.

Exhaust Nut

Had to cut into the nut to get it loose. That does not matter since it is wery corroded and has to be replaced anyway. Thread is 20 TPI and I measured the outer diameter to 44.3 mm which I presume is  1¾ inch (44.45mm).

The new nut will be made from brass or brose. it will also be made for use with a hook wrench insted of a regular spanner.

At the same time I dismantled the valve gudes and destroyed my valve guide tool that was special made for another engine ..

Carb

I'm not sure the carb can be fixed. It's heavily corroded and I suspect the main jet can't be dismantled without destoying the threads or something worse.

Cheap fix

Since the Mark III engine was stuck, my fear was that the cylinder had been flooded with water and was a complete rust-disaster. At least the air filter was full of water...

Guess what, the rust was not that bad even if it is very worn and has some damages, it probably could be made to work. Only had to spray with penetrating oil and wait a couple of minutes to free the piston.

After some light grinding with 400 grit wet sand paper soaked with WD-40 (oil), the damages are clearly visible.

Annealed copper cylinder head gasket lightly sanded.

Amal 225/3

The carb for the Mark III is like no Amal I've seen before.
Wonder if it's possible to get spares if needed?
At least a visual inspection shows that the tickler is missing.

Newsflash

Got me another JAP engine project too as well as the Howard GEM Rotavator ( rototiller) it is attached to. The engine is a 600cc s.v. Mark III Type 5

Engine number is:
UCZ/Z
94433\5

If I'm correct that would be:
U = 600cc Side Valve Engine, 85.7 x 104mm bore and stroke
C = Sports Engine
Z = Dry sump Lubrication
Z = 1933 Model Year

U is a standrd 6hp (4½ hp nominal) engine, according to The JAP book so what with the C marking?

The JAP Engine Reference there are more alternatives and the Mark III engine is recognized as a Sports engine.

My hopes were that I could get it started. By lubricating with the famous Omega Omicron  636 penetrating oil. So far I have got the valve lifter, throttle and most other leavers and functions to work.

Unfortunately the next step is to dismantle the cylinder head to see how bad the cylinder and piston is since the engine is stuck.

Inspiration

Found a bunch of pictures on another blog. Obvious staged, the same chain-less Excelsior appear on many of the pictures with different drivers.

All together

Small step

Made some progress with the valves. Unfortunately I have a house and a garden and it's spring time and ...

Anyway, managed to mill the holes in the valve stems and cut them to the appropriate lengt. Since I do not have any valve grinding machine I will have to make a jig to grind the end of the valve stems. Hopefully this weekend (as long as the weather is rainy I can't do any outdoor painting).

Gearbox

Visited a swap meet today. My intention was to buy a Sturmey Archer 3-speed gearbox. For some reason I bought one Albion 3-speed and three Albion 2-speed gearboxes.

I maybe could use the 3-speed for the Baby Nut but why did I buy the 2-speed gearboxes. And I do not think I can get one working 2-speed out of the three of them.

End mills

Finally got the end mills I ordered all the way from China. Sold as Solid Carbide HRC60 and as such they should have no problem milling stainless steel stems, or...

Valves

According to an old James Catalogue, the valve dimensions are as follows.

According to my measurements the valves are somewhat longer.

Anyway I'm not patient enough to wait and see if any JAP valves will pup up so I scanned through some valve makers catalogues and found out that Manley GEN II exhaust valves are pretty close.

Found a set of eight valves for sale on eBay. These were custom made and the valve head was close enough to fit without modifications.

Valve head = 1.6" & Valve stem 7mm

Of course they will have to be shortened and modified with slotted stem ends.

The main concern is if they are too heavy compared to the original ones.

In case they can't be used I'll buy some used NASCAR titanium valves and try to modify them instead ...

Collection

For inspiration I went to the local MC Collection an took some meausrements and pictures.

Especially the unrestored 8-valve Indian racer was scrutinized. Took a lot of pictures of frame and fork details..

Oil Pump

It seems I can not get hold of a period correct oil pump.
When bidding on eBay there is always someone that has more money.

I'll use a Jawa oil pump, if possible, until I find a suitable Pilgrim or a Best & Lloyd or...

Valves

Still have not found any valves. An option is to adapt valves from a newer/modern engine.

Using valves with cotters would mean I have to find suitable collars too.

Intake and exhaust nuts, prologue

Rusted as if they were welded to the cylinder, but at first I had wery low expectations regarding the Spark Plug and Valve Cap too.

Maybe this will solve it self after the cooling fins have been welded. Either by the heat from the welding or when the cylinder cracks when cooling after welding.

Intake

Tried with an adjustable spanner but did not dare, in fear of ruining the nut. After more soaking in citric acid it looks like the thread is left handed.

Anyway, the thead has been soaking in penetrating oil while I have been loking for a ring spanner with the appropriate dimension. Measured with a cheap vernier caliper it measures about 32.5mm. Have not been able to find such a spanner. The closest I have found is BSF 7/8 or BSW 3/4. That would be 1.300“ or 33.02mm which it could have been before all the corrosion started.

I think I'll try a 32mm ring spanner and with some luck that will fit. Buying a imperial size spanner is the last option. I might even grind / open up a metric open end spanner before that.


Exhaust

This one is a real challange. Maybe I'll try to cut the nut to get it off.  Both because the required spanner and the condition it is in.

Think I might have to make a new nut anyway... maybe from broze or brass?

Valve Cap

Made out of aluminium, but just got one out of two.

 

I'll try to manufacture a pair in my lathe even if the hex head is not that easy to make in a lathe (have not got any milling machine).

Wonder what thread it is? The pitch is 1,5mm and that would correspond to 17TPI and that is no standard thread as far as I know. Will make the hex head 38mm which is 1 1/2"

Cooling fins

Made from sheet metal since I could not find any large enoug cast iron cylinder to scavange.

The tricky part will be welding them to the cylinder.

Cylinder

After three days in a bucket with a mix of water and citric acid followed by a light brushing with a wire brush.

Now it's time for new cooling fins.

Notice the mark on the intake tube where the level of the ciric acid water has created a visible "border" in the rust and dirt. I still do not dare to try to open the intake nut. I also think it's treaded the wrong way, so to say.

Small Timing Gear Puller

To remove the small timing gear on the crankshaft I had to make a special  puller from a steering ball joint puller. Colonel Johan August Sandels is overseeing the procedure.

Engine identification

The engine was sold as a 250cc and the engine numbers might suggest that too. At least if one thinks /B stands for the cc.

Nothing seemed to add up and I could not figure out the meaning of the numbers and letters. When I measured the bore and stroke I came upp with approx 70x89. That would be 350cc I my book.

Trying to decode the serial number by the info on http://www.railtruck.org/jap_dating.htm I came up with the following:
I/S     I=350cc side valve, 70x90mm bore and stroke, S=1929
75163/B      75163=Serial number, B=Modified gear cover and exhaust valve lifter
H      H=Roller bearing pulley spindle
M     M=Crankcase without oil box.

Of the above everything seems OK until the letter M. At least there is something I would call an oil box.

But of cause the last paragraph on that page says "... this list is by no means infallible." 

Parts List

The parts list is not easy to find but I finally found it, or so I thought.

Comparing the engine I have got to the sectional drawing in the parts list I found, shows that the are not exactly the same. From the parts number found on my cam follower (6170/F) compared to the ones in the parts list (6176 & 6177), one could believe my engine is older? But if the years given for the parts list, 1919-1926, are correct I doubt my engine is older than that.

Fault 02 & 01

If I thought yesterdays find was a major fault, then todays find was humongous.

Both valves are crap. The one I managed to get loose, in the picture. The stem is completely worn out, the same of cause, goes for the valve guides.

The missing piece from the cam follower appeared today. Probably broken off when the valve seized or when someone tried to turn the crankshaft and the valve was stuck.

If anyone have an extra cam follower ( Parts no 6170/F ) feel free to contact me.


The one positive thing that I found out today was that the piston seems OK. No scratches and all three piston rings are loose.

The marks below the rings are caused by oil.

Fault 01

Started degreasing the engine, today. Opened the camshaft / rockerbox to make sure there was no water inside the engine.

Found a major fault: one of the rockers was broken. Unfortunately the broken off piece was missing, otherwice I would have tried to weld it back...

If anybody out there has a spare rocker, feel free to contact me.

J.A.Prestwich Industries

J.A.P might not need any further or deeper presentation, but anyway.

English engineering company and engine builder,  founded in 1895, defunct in 1965.

Made a wide range of SV and OHV engines, for motorcycles, stationary engines and cars. Both single cylinder av V-twin engines.

For me personally, I recognize the JAP brand mainly from their succes on the Speedway tracks.

N.U.T Motorcycles

There are a few sources on the internet about NUT Motorcycles, the name is derived from Newcastle Upon Tyne.

The short version is: From 1913 they competeds in motorcycle races and won the Junior TT at IOM. From 1914 they made motorcycles under the NUT name. Did not survive WW1, were declared bankrupt. Company (name) was bought and motorcycles were made from 1921 - 1933

Have not found much refernces to the NUT BTR (short for Board Track Racer from here on). Would like to hear from Trevor Hall and hear if he has any stories regarding the BTR's.

How it all started

For many years I've been drooling over pictures of old Board Track Racers as well as I allways wanted an old side valve engine to fondle with. Of cause there are a couple of them that I can pay a visit to at the local MC Collection whenever I want. That's just not the same.

The other week I was going through adds on the eBay and found this restoration project. An old JAP 250cc S V engine.

It was missing a lot of expensive parts as the Carb, the Magneto and the Oil Pump but I took a gamble that at least the internals would be possible to salvage and bought it more expensive than first planned, but what the heck.

When I later was scanning the internet for a parts list I stumbled over Trevor Hall's 600cc NUT Board Track Racer. From there on it was just to hang on and "go with the flow"

Rest of the few pictures of it can be found here.

The intention is NOT to build a replica of the above pictured racer. It is going to be my personal interpretation of a Board Track Racer, that will hopefully look a bit like the NUT