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21
British Bikes / Re: Troubleshooting a JAP Special
« Last post by Rockburner on August 03, 2026, 07:16:09 PM »
Apparently all the oil I lost on Sunday was generated from the dark matter of the universe...


7cm is exactly what I measured Sunday morning before I went out.

I wiped up some of the dribbles, then started looking at the plug because re reading the link about the Magneto, I realised I'd never checked the plug gap.

Apparently it should be between 0.018" and 0.020".

"That went in a bit too easily" (Bishop, to Actress, 3rd September 1933).


So did that...


So I dug out my Champion Plugometer! :D


What, you don't have a Champion Plugometer?






Call yourself a petrol head? Tchah! :roll:

:)

Anyway.... The gap was definitely a bit wide so I tweaked it down and hopefully that might make a bit of an improvement.

I WAS going to try to straighten up the little nose cone, but after I took it off, I'm realised the thing is actually twisted au natural.... FFS. So I put it back on.


Another little job I wanted to do was to round off the fly screen. So I had a go at that with the Dremel and a small file.

It's not perfect, but I'm reasonably happy with it for now.




I may have an hour or two of time tomorrow to get out on it again, still want to see if the Selsey JAP man has any info on one or two questions I have.
22
British Bikes / Re: Troubleshooting a JAP Special
« Last post by Rockburner on August 02, 2026, 06:52:13 PM »
There's always more to learn....

Last night I left a clean bit of newspaper under the bike after I'd run it up briefly.


This morning....


I'm pretty sure the culprit is the pump , which is not a surprise at all.


But it's only a dribble, it's livable with for now.

Today's plan was to get a few more miles on the bike, by visiting a Cars&Coffee about 20 miles away, then heading over to the Selsey RNLI charity event.
First I topped up the oil and petrol


And while I was at it I spread a little silicon into the Monza cap rubbers


Then set off, not without a little trepidation I have to admit!

But the bike is transformed! Fuelling at pretty much any throttle opening as pretty damned good!  :banana-wrench:  :banana-wrench:
So many thanks to the guys who pointed me in the right direction!  :obscene-drinkingcheers:

It does have a tendency to spit a touch after a prolonged period of constant small throttle opening (ie 30 zones and following dawdlers...), but once you get "on it" it's fine!

There's still a dribble of oil escaping from the push rod tube (inlet), but it was only a dribble.


On the way back towards Selsey, I even got lucky enough to get an empty bit of smooth tarmac and wound it right open!  :angelic-green:


Chin on tank..... The needle crept round the dial...

68...

69...

70…

..

71!


72!


...


73!


:lol:

Flat out is maybe 75 on the Smiths! :lol:


But the engine felt happy doing it!


Obviously though, by the time I got back towards the coast roads, the traffic built up and it was back to pootling along at 40....  :roll: yawn.

The vehicle gathering at Selsey was (tbh) a little quiet,



The ride home was more pootling, which the bike still doesn't like, letting me know with the occasional spit and hesitancy, so I decided to try and give it a bit more of a go by hitting the A27 just for a junction.

And got a bit of a shock.  I'd just wound it open again when the thing died on me! It felt like either fuel station or lack of spark, then it picked up, then died, then struggled on again....

By which time I'd reached the next roundabout and peeled off for home.

Very odd.

The engine was fine again at low speed, then I got lucky again and had a clear run to the house, so I opened it up for about 300 yards then cut the engine to roll into the driveway on a dead engine.

The result. Black, but dry, the insulator isn't completely black.


I need to review the plug condition photos, but I don't think it's that far off...
Just need to figure out if it's a tad rich, or a tad lean.

When I had it WFO previously I did try easing off a tad a couple of times, and the engine just seemed to roll off, rather than gaining or complaining.

More testing required methinks.

Note to self... Top up the oil on the side stand!

Obviously, the bike was parked on its side stand during the afternoon, and I think it started dribbling then, because the was a stain on the thigh of my trousers....

I also remembered that I had Sealey pressure testing kit, so took the opportunity to check the compression while the engine was hot.



Hmmmmm, that's actually a little lower than I was expecting...


I should have checked it the last time I took it out, to establish an early baseline.  I think I'm going do the compression ratio test soon, so we'll see.
23
British Bikes / Re: Troubleshooting a JAP Special
« Last post by Rockburner on August 01, 2026, 09:48:37 PM »
So this carb stuff has been playing on my mind, so I blagged an hour today and nipped into the workshop.

First job was to fit the replacement jubilee on the oil return feed


I then reviewed the Amal Concentric rebuild guide, (which I've read a couple of times now...) and specifically looked for information and photos of the component parts, and there's a lot of information in there. https://amalcarb.co.uk/technical/rebuilding-mark-1-concentric-carburetter

First I wanted to reassure myself that the carb for a 4-stroke:
Confirmed!


Then stripped the jet block from the body.


And pulled the needle out.
It's the right length (near enough)


But, these two jets, are (according to the info in that link) for 2-strokes.
The 107 is the one I pulled out of the carb yesterday and (iirc) was the one it came with.


These 3 are correct 4-stroke needle jets (all 106)


I am rather confused as to how I've ended up with 2-stroke bits tbh.

So I replaced the needle jet with a correct 4-stroke 106 jet and kept the 206 main I'd already fitted.


The needle jet stays on the middle notch, but cross-refencing to the Amal information, it's the one with 2 grooves, which is the correct part.

Stuck the needle back into the slide (it's a 3.5), and refitted that into the body


Refitting the jet block, with the needle already in position it means there's no buggering about trying to fit the needle into the jet block of it's in situ.


The needle pulls to the right slightly at WFO, but it doesn't seem to affect slide movement.


All back together again. :D


As I was tidying up I found a brand new 260 main! But I want to change only one thing at a time, so that might be the next thing to try if there are issues at full throttle (which is the only part of the throttle range where the main jet has an effect)


I replaced the tank strap


Checked the oil again now it's cool, roughly the same as before


I then went to fire it up but fuel wasn't coming through, I poked about a bit then realised that the fuel tap was being fouled by the jubilee clip on the pipe!
Little details...


So I tweaked the tap because it had rotated a bit in the tank fitting


I refitted the 90 degree union and turned it away from the tap a bit.



THEN I could fire it up again! :D
I still can't believe how easy this thing is to start.
Everything seemed ok, and in the 5 minutes of idling there didn't seem to be any leakage from the push rod tubes. :)
The pump action is mesmerising...
https://youtu.be/zavcxQrl1vQ?is=NHoJ1tWF2tlLldTZ

Hopefully going to get out for another longer ride tomorrow. :D
24
Identify these bikes! / Re: L'il Villiers
« Last post by 33d6 on August 01, 2026, 02:43:46 AM »
I think we have it pinned down. All that remains is to find out the frame number to confirm it.
25
British Bikes / Re: Troubleshooting a JAP Special
« Last post by Rockburner on July 31, 2026, 11:44:47 PM »
Another long session in the workshop this evening!

Just one thing first, after the ride on Thursday I measured the oil again...
If 2cm was 500ml... 0.6cm is around.... Errr.. 180ml, ish? That's a lot to lose over 23 miles....


Started by giving the plug another quick Milyarding


The shed was hot, but I didn't expect it to be this dry in there...


Then took a good look at the tank to fix the issue where it's not sitting correctly.


First I discovered that this jubilee on the oil return pipe was shagged, which it turns out was not the cause of that line weeping... More on that later...


(I have a few spare jubilees...)


There's a union nut that screws onto this, but it's obviously been forced up the tube because the two thread forms are different. FFS.


The tank was rubbing badly against the down tube.


It'll need a repaint at some point. :(



I found an old BMW part that I initially thought I could adapt, so I made a start on that work,


Always take the burrs off first....

(I'm sure I took more pictures...)

Then I realised that the rubber bungs could be used in a better way.
I cut one into half


Then simply cable-tied them to the down tubes, after cutting grooves for the ties


The new pads fit perfectly in the gap between the tank and the headstock


They'll keep the track nice and central.


So I pulled the tank off again, and in doing so the flaming oil tap caught the frame and dribbled everywhere!


D'oh!

I took the tank off because I wanted better access to the engine head while I tried to get the oil leaks sorted out.
I pulled off the breather and the rocker cover so I could redo the RTV.

I used the rocker clamp so I could remove the push rod and tube completely


Then tidied up the old RTV (which is really easy), before figuring out that hopefully the best way to apply the RTV was to fill the annulus at the bottom of the push rod tube with the stuff


Did the same to both tubes and refitted them


Spooge!


Refitted the breather with better loctite, the stuff I put on last time didn't do shit. I also tightened it up more with pliers.


I then spent some considerable time looking for a union nut that would thread properly onto the oil return tube. Eventually found one, but I needed to drill out the opening slightly to accommodate the suitably girthed hose attachment.


I think that because of the damaged threads, the previous union nut here hadn't sealed properly and that's why the feed line was weeping. Fingers crossed this one fits better! It certainly seems more solid.

I then took a look at the carb jets to see what needle jet was in there.
Hmmmmmm, that might explain things a bit....


So I fitted this one.


Oddly my needle jet collection are all 106s... But they're a different design:
The 3 on the left are 106s, but maybe for a different carb? The 4th is the 107 just removed, and the 106 I put in is of the same type where the entire jet tube is the measured bore, not just the bottom end.


We'll see how it runs on that, hopefully I'll get out on it this weekend. :D
26
British Bikes / Re: Troubleshooting a JAP Special
« Last post by Rockburner on July 31, 2026, 10:48:31 AM »
Quote from: Rex on July 31, 2026, 10:00:06 AM
That bog at Bracklesham is a throw-back from the 1950s which is probably the last time it was deep-cleaned. How long can you hold your breath?
I like the bendy road back to the A27 though.

Not long enough... bleuuuurgh!

Too much traffic around these days, the bike doesn't like constant speeds (especially below 50), it wants to be ridden! :D
27
British Bikes / Re: Troubleshooting a JAP Special
« Last post by Rex on July 31, 2026, 10:00:06 AM »
That bog at Bracklesham is a throw-back from the 1950s which is probably the last time it was deep-cleaned. How long can you hold your breath?
I like the bendy road back to the A27 though.
28
British Bikes / Re: Troubleshooting a JAP Special
« Last post by Rockburner on July 30, 2026, 09:26:16 PM »
More Thursday afternoon Shenanigans!

Frist I tightened up the pumps, we'll see if that makes any difference whatsoever (I doubt it)


I checked the level in the oil, it was showing exactly 4cm (which is a bit odd because I could have sworn it was a 4.2cm when I returned from the  ride on Sunday, maybe the oil shrank in volume as it cooled? Either that or there's actually a leak somewhere.... which I doubt...)
I then added another 500ml... and the depth went up to 6cm.
So... 500ml is APPROXIMATELY (the tank isn't a uniform cubic shape...) 2cm...  Interesting.  6cm is roughly half-full.



I was then just going around the bike checking things and realised the bloody tank strap was coming apart.
So I pulled the thing off (easier said than done, natch...), punched a couple of new holes a bit futher in, and refitted the end piece


I moved the attachment point to the forward of the two holes and redid the pretty wire... :D


To be honest, I really don't like that tank fitting.... I am going to think about improving it somehow.  (more on the tank later....)

Tacho don't work.


(but the rest I think is reasonably accurate)

I pulled the plug which I hadn't done after the last ride on Sunday.


Black and sooty.... to be honest, I'm completely unsurprised.  The ride home was at snails pace and the engine was not happy at low throttle settings.


I gave the plug a quick Millyarding




And chucked it back in...
Note to self.. FIND A BETTER PLUG-SPANNER  I hate this cheap piece of tat.


I checked the engine was still running ok, fired it up and it was fine, so I tweaked the oil slightly, and the idle speed (REALLY easy to do that with the extended adjuster screws! :D )
Even just idling in the shed there was some oil coming out of the push-rod tubes, but the crank case breather was working well, and was surprisingly dry.


So, I took it out for a spin. :D
Selsey Beach.  I actually had an ulterior motive... I need to talk to the local JAP expert in Selsey about the engine so went down to see if he was around, he wasn't, so I took the opportunity to get a photo or two at Selsey Head.



I then fancied an ice-cream so wended my way slowly over to Bracklesham (the next village west along the coast).
Even taking the back roads I was baulked by traffic virtually everywhere...


I did assuage the frustration by overtaking a few cars and trucks though - maybe not much to brag about, but it felt good given the bike I was on. :D

The engine breather, I think, has actually helped the engine run a tiny tad better, it seemed a touch more eager today.

One thing it DEFINITELY does NOT like is pootling along.... it's quite positively happier at 3/4 to full throttle and when it's pulling.  It does NOT like trundling along at 30-40 on a constant throttle... I had to adopt a sort of "hyper-miling" technique of dropping back at idle, or with the clutch pulled, then letting the engine pull up to the car in front before dropping back again.  I'll have to look at the tuning guides and see which part of the carb is effective in that range - I "think" it's needle height, so that may need some fiddling with.

I then took a slightly longer route home (to avoid having to turn right into the driveway... :roll: ) and got a run through the local tight bends - the bike suspension may be somewhat hard and jarring, but it handles beautifully, holds a line and tracks very nicely, I can't wait to get it out on some open sweepers. :D :D

Oh yeah - I also tweaked the side-stand round a bit on the frame tube, and the bike sits up a bit straighter now, which I much prefer. :)

There's still a way to go yet though: things that need a good looking at:
- carb tuning
- oil leaking (hopefully some RTV on the push-rod tubes will contain most of it).  I have a nasty feeling there's a couple more areas though. The oil return feed line leaks where it goes into the tank, which confuses the hell out of me because there's absolutely no reason for it to do so - I even trimmed a cm off the end because it was looking a bit tired and it's made no difference. Hmm....
- the tank, yeah... it's rubbing against the steering head (well, the rhs downtube actually) and it doesn't sit centrally on the frame pads.  So - I need to make up a boss or something to hold it centrally... hmmm... I just remembered I have something that might do the trick... <makes mental note>
- LHS fork needs a new seal, and I may as well rebuild it (I hate rebuilding forks...),  On Sunday the seal seemed fine, but it was weeping today, it needs doing.
- Tacho - I suspect the speedo is just some old thing Dad bought at Kempton, so that may be a winter project to see why the Tacho isn't working.


It ain't over folks! :D
29
Identify these bikes! / Re: L'il Villiers
« Last post by cardan on July 30, 2026, 05:01:46 AM »
Brilliant - very interesting indeed.

I spent last night reading military vehicle forums about the ML James. Incredibly well documented due to the military contracts that governed their production and delivery.

Of interest to us is that MLs were delivered between 1943 and 1945, with frame numbers up to ML8500 - there were contracts to supply 10,000 but the last 1500 were not delivered to the military. ML numbers beyond 8500 ended up (mostly) on the postwar civilian market.

Now here's the interesting bit: All the ML engines (Villiers 9D) were all AAAxxxxA numbers, with xxxxx mostly between about 20000 and about 28000.

The experts there agree about the A suffix on the 9D engines: "Unfortunately records of Villiers 9D engine numbers do not appear to have been retained but it is thought that they were fitted to WD James ML's at random without any particular sequence. The suffix "A" after the engine number was a mark applied by Villiers to signify a post-1939 9D engine with the revised crankcase sealing method (the "gland" seal on the driving side), the "A" signifying "amended"."

They also suggest that, unlike the ML frame numbers, the Villiers engine numbers don't seem to appear in strict order. Nevertheless, the Waratah engine number AAA24024A is right in the middle of the 8000+ engines that went into MLs for the military, do it's likely well into wartime: 1942, 1943 or even 1944?

So, what date for the Waratah?

I've been back and searched wartime newspapers. New Waratah adverts petered out towards the end of 1941 (ignoring Ted Bailey's unchanged long-running advert in "The Propeller" claiming to have New Waratahs on hand), but there was a surprise advert from P&R Williams offering "a few New Waratah Motor Cycles" in December 1942. No mention of the model, but let's guess 9D engines.

The post war, I found an announcement of "limited quantities" of 1945-model Waratahs in September 1945 (all 9D). The "Brand New 1946 Model Waratahs" landed in July 1946.

As I see it, the Waratah for sale could be either a "1942 surprise shipment" landed in December 1942 or a "1945 model" landed in September 1945. I'd guess bikes in both shipments might look pretty prewar, with the "1946 model" having what we call postwar features - new frame, gear change through the tank, etc.

I'll try again for frame number.

Leon
30
Identify these bikes! / Re: L'il Villiers
« Last post by 33d6 on July 30, 2026, 03:16:59 AM »
From what you have given me I think very early postwar. It all seems to point that way. As it happens my Excelsior equivalent is a 1940 model so more or less last gasp prewar and very handy for comparison.
Supposedly Villiers did their final 9D upgrade in 1939 but when in 1939? War was declared in September which is also around the time the whole motorcycle industry including Villiers started announcing next years ranges and anything new. I'm still ploughing through 'MotorCycling" at the State Library and haven't got to 1939 so haven't an exact date yet but will in due course. 1940 was going to be a big year for Villiers. Lots of changes and upgrades that came and went between the declaration of war in September and the halt of civilian production in April 1940. Hopefully the State Library will clarify a lot of questions.
My Excelsior has the AAA prefix only and the number, 18330 is in the expected prewar position. The frame number is 1073 with the correct prefix for a 1940 Model 0. It is on a flat boss on the left side of the steering head lug just above the down tube. The frame number is always on the special raised boss provided for it. Your auctioneer isn't trying too hard if he can't find it.
The first batch of postwar Excelsior to arrive in Victoria all have AAA****A engine numbering system in the vertical style. We know this from the AOMC engine number cards as they all contain the date of first registration which leads me to believe its the original fitment with the auction bike.
We also know from past investigation that a Waratah /Excelsior was not quite the same as the current model Excelsior . All Excelsior but not quite identical, usually with the odd part from previous years models. I think that is what has happened here, in an effort to start selling bikes again in the early days of peace Excelsior cleaned out their stores and made up a batch of Waratah from what they could find. As I mentioned before, that bike has a prewar frame and forks that were used on other model Excelsior. The frame number would reveal a lot. I think it's genuine and very early postwar. 
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