Hello, I have a bit of an issue as I keep using my B40 to get to work, natively believing that the issue will clear itself!

It hasn't and after a very sweaty and sweaty trip to the office I feel like the thing has given up.

It was running very well a couple of weeks ago, last week I noticed once I got it into 4th and was travelling at along at about 40 it stated to misfire. I didn't think too much about it as it seemed to clear itself up.

I checked the plug and it's a good colour.

Then last Friday I was on 3rd and it started to splitter and bog, switching down to 2nd and revving seemed to sort it temporarily ,then on going back up to 3rd or 4th was misfiring badly and not revving.

It then stalled and was a pig to kick over, bit once it did it idled.

Pulling away it spluttered bit keeping it in a low gear and revving it seemed to be the only way to keep going. As soon as I went up a gear it just splitters and dies.

Same story today but more of it, easy to start first thing, will run in 1st and second with the odd misfire, 3rd patchy and 4th unrideable. 

Carb is original amal, was ultrasonically cleaned and has new jets,
It has vape ignition and is 12v.

It idles nice and cleanly, it revs up on the stand in neutral ok.

It now pops and bangs on the overrun where I believe it wasn't so much a couple of weeks ago, sounds like an air leak.. bit why not all the time, and why does changing gear affect it so much?

I did notice an rear indicator bulb has blown .

Thanks for any help!!!

My points were never quite right, I expect there was a lot of wear, I couldn't get it idling right and although I was spot on with the static timing it would wander at idle and cough and stall randomly even when warmed up. That often caused annoying junction kickstart sessions (the kickstart also chose this exact time to lock up at the top to add to the fun).

Of the various choices I decided to purchase the Vape kit sold by Wassel, my reasoning was that the components are encapsulated in resin and there aren't any exposed dry joints on the board. I felt this gave it the best chance of surviving the vibrations.

Fitting was very easy, my old points plate fell out of the taper with a slight wiggle, the cable wasn't quite long enough to be easily routed through the inner case (and I didn't wasn't to breach a perfectly oil tight seal either to be honest). If I'd been more professional, or the owner of a had a shinier bike I would have extended the cables and done it properly , but as I am neither I Dremmeled a little notch in the case under the points cover.

Wiring was also easy, I made a point of giving the coil a nice big positive cable all of it's very own direct from the battery, as although the nest of wiring that exists on my bike provides several questionable earths, they are akin to oily old string at this point.

After spending an hour or two and a beer or two deciding where to mount the tiny little box I was done, and the only other thing I decided to do was open the plug gap up a bit  to .40 and index the plug to give it the best chance of making bangs.

I am really happy with the static timing, I can get the idle really low (for no reason other than to prove to myself that the cost was justified). I need to time it with a strobe at some point, but here we go, a good start:

https://youtu.be/4ShF27Txu6k?si=OhTZSnHIVxaeIsFm

Here is my 65 B40, it's not going to get above 3 degrees for a while so thought I'd get out for an hour or so..

Hi, are the head stud holes in the block open to the crankcase? My head gasket is dry, as is the base gasket... but I have oil on about the third barrel fin up. When the bike is running, if the bike is on the side stand I get a spot of oil on the primary cover.
I can only guess that oil is creeping up the threads on the left rear stud. I was sure I used thread lock on them!
Thanks.

Hello all,
I am now at the point  in the restoration where I can ride up and down the road!! Big step!
I have noticed however, that getting in and out of first gear is incredibly stiff (I can see  why those splines are worn!).
It is at about the limit of adjustment on the clutch lever, I can see the basket moving although it's very heavy to pull.
It just doesn't seem to want to change into gear without a lot of pressure on the foot lever.

The gearbox has been rebuilt  and the clutch has new plates/springs.

Thanks

Hello, firstly thank you for having me! I have recently been fortunate enough to acquire a 1965 B40 that has been off the road and apart since 1979.
It came to me in bits, with the bottom end and gearbox having been rebuilt in '79 with a +40thou re-bore and a high compression piston.
I have assembled the engine and put it in the bike.

The Amal 376 apparently had a new slide, but the rest of it's internals were caked in various amounts of yellow/grey sludge and aluminium corrosion, I have cleaned it as best I can with carb cleaner and cleaned the jets, I have also put a new float needle in. The mixture was 1.5 turns out.

The ignition timing was completely off and the spark was weak, I did the static timing with a continuity meter and set it so that at on the compression stroke, 33.5 degrees before TDC just breaks connection (with the auto advance locked out), I can demonstrate that bit worked by releasing the auto advance and pushing the cam around with a screwdriver, it breaks connection just as there is no more movement in the cam. The sparks at the plug, however look a bit weak and inconsistent (it is still 6V though).

Hope you are still with me!  And that this sounds about right.

I tested the coil, I get 2.4 Ohms across - and +, and about 4.7K Ohms at the output.

I cleaned the terminals and tested the spark plug wire, 3 Ohms.

I have 3 plugs with the bike, an N5, an NC4 and an NC5, all gapped to .20. After about 20 minutes of fruitless kicking, I can get it to start ( ferociously) with a touch of throttle, and what I presume is full choke, pulled all the way towards me.
It seems to fire about half the time, is very slappy sounding and produces a lot of black smoke. It is uneven and has moments of clarity when it seems to pick up and run at double time, then back to a slappy, chuggy mess.

It won't idle, and needs throttle the whole time. The choke seems to do nothing and it uses about 100ml of fuel in about 1 minute of this very bad attempt running. The bad news there is that I think most of the petrol found it's way into the oil, the good news is that there is only one oil leak, and it is from the tank.

I have deduced from this that the mixture may be rich...

Any help would be greatly appreciated, should I scrap the carb? Should I go 12V and electronic ignition?

Thank you,
Grim.