I think I have the correct magneto on my Norton, plate reads M01-4 465110 AG4 542. This unit is anti clock from the points end and wire in the left side. I need to know if I have the correct points cam, mine has R stamped, points open around the 4 o’clock mark, would this be correct? and plus I don’t seem to be getting any response when I pull the mag lever
To check your face cam is correct the points should just beging to break when you turn the armature in the direction of its drive. You will feel a slight resistance as you turn it this is the armature in the magnetic field the slight stiffness is the armature leaving the magnetic field. This is when the points just start to break if you have the correct face cam.
Your magneto lever will pull the cam to its stop via the cable if you have it conected up correctly with the correct length return spring fitted in the end cover.
Tim W
The AG4 is the correct mag for the WD16H (or at least the data plate is correct !) Rotation is clockwise when viewed from the driven end. pick-up and A/R cable are next to the engine.
The face cam should be marked 'R' with the cam dropping at about 5 o'clock and lifting at about 2 o'clock.
Tight wire advance. I can take some photos of my spare mag if you're stuck.
Thanks Tim
Rik yeh I have the correct mag, the face cam is what you described, points open at at 5 o’clock and not 4. i though the face cam was wrong. I’m only checking this as I can’t get the bike to run properly, well it’s was running ok until the mag moved, so I had to read adjust and set timing but now the engine runs like a piece of crap, spits lots of fuel out of the carb, I’ve move carb needle up and down, if I raise the needle it won’t run at all. I just thought something was putting the timing out
If fuel is being spat out of the carb then it would suggest the valve timing is out - i.e. the inlet valve is open as the piston rises to the compression stroke.
Just a thought as the first 16H I bought did that - re-timed the inlet valve and it has run as sweet as a nut since then and that was 1978.
Could possibly be the inlet cam. I might have to double check, I wanted to rule out other bits before I have to take of the timing chest, my cams had marks on them which some body must of put on em, they seem to be in the correct position as per manual, maybe the inlet could be out one tooth.
Rik have you got a pic of you mag points end? I just want to take a look at the cam fitted
Ron it’s definitely on the opening, I use fag paper. I think I got all sorts going on, the points gap is set at 012 and in between its open cycle the points closes a little in the middle and opens slightly either side before they close or after their open, must be something wrong with that face cam and also I just checked the points against the inlet valve, the valve is just about to close as the points are just about to open, maybe the cam wants going back a tooth??
I might be reading it wrong and it's ages since I timed a Norton (clockwise at the drive end) But you say your points break at 5 o'clock which I think what Rik says and from memory is when they close and then open at 2 o'clock??? Ron
Barry, you ought to have the points at about two o'clock as the fag paper comes loose. It sounds as if you're turning the points block clockwise and setting the timing on the down-ramp going backwards...As you're on the back end of a clockwise mag, you should be turning the points block anti-clock.
I wouldn't worry too much about the fuel spitting. The valve overlap on 16Hs makes them prone to it and if there is no ignition then there will be lots of unburnt fuel around.
I’ve re set the cams and timing, bike seems to be starting better but when I rev hard it pops and bangs through the exhaust and carb, this could be the mag breaking down??
I never fit a mag till it's been to my bloke for a proper overhaul and rewind. Otherwise it's just guesswork and wasted effort. If I have a query with any mag he'll put it on test for an hour while we chat and he shows me any more interesting magnetos that he's been commissioned to overhaul. :+1: Ron
As per Ron. Fiddling around with a possible duff mag is soul-destroying. I assume that the carb has been fully stripped and cleaned and has the correct and unique Norton jet block ?
After stripping and cleaning the mag, fitted new points and earth brush, it seemed to have a nice big spark while spinning it with a drill. I thought it might of been ok.
Has anyone got a pic of the correct jet block as fitted to Norton 16h carburettor??
The part number for the 16H jet block is 206/058. But I completely forget what is unique about it? Is it like the Matchless G3, with no bleed hole? Hopefully Rik can remind me! Ron
There’s an old post about this on the forum but non of the pictures are coming up. I’m sure it just has two holes at the back?
My jet block has 30T stamped on the bottom and 5 on top, has four holes round the bottom, thing is if my carb was fitted with this jet block it must of worked run at some point in its life. I’m also curious to how thees stub fit carbs seal properly.
I’ve removed the mag from the bike and just got to fined somewhere who can re build it for me
A picture would be handy as what you are describing sounds very much to me like you have a 76 jet block and not a 276?? Here is a 76 carb on one of my Velo's. would your jet block have the four corresponding holes to line up with the four in the body.......It might still work of course???
There should be slits in the carb spigot and the clamp should easily squeeze it gas tight onto the inlet stub Ron
Ron my jet block matches your 76 carb, I would add a pic but I use an iphone so I ain’t got a clue how to put pics on hear, il email a couple of pics Ron.
I’ve just found what looks like a 206R block with the big hole on the choke side, I might cut and drill out my Norton carb body as the inners looks the same as another 276 carb?
Regrettably, the photobucket debacle has disabled most of the older images on this message board and I can't go back in to edit.
These are the three main types of 79/276 jet blocks (they can also be 'handed' but the same principle applies).
Left to right - Type 76 - 276R - Norton Type
Very early Norton 276 bodies did not have the cast 'gusset' under the inlet mouth, but after this was introduced and bored out for the 276R, it appeared on the Norton casting also. The Norton jet block is quite scarce.
I've not heard of anyone opening out a Norton body. There are other differences including the 'overflow' slot so you'll need to look carefully and make sure all the drillings line up.
I've never had a problem clamping the Norton carb onto the stub...if everything is in reasonable condition.
Thanks Rik
Rather than messing up my carb il think I’ll look out for the correct jet block. The stub to the fit the carb is NOS item from Russell’s so I know it’s a tight fit.
Did you disturb and had to reset the timing gear when you took the mag off?
The manual says to remove the outer timing chest but this is entirely unnecessary using socket sets. I replace the mag to my scratched mark. As long as you leave the engine unmoved that saves time.
Ok 3 types of jet blocks the four hole type matches the body with four holes, The jet block with about 1/4 inch hole in the front matches a 1/4 inch hole in the body at the front and the body has a extra lump in the front. The Norton jet block as fitted to some Nortons and specific to Norton has no holes on the body and the jet block at the front has the 2 1/8 inch holes and the flat recess as shown in the photo of this thread. Regards John
Jeromy I’ve re set the cams anyway, I manage to get it to run briefly but the mag decided it wanted to pack up so I’m still finding somewhere to refurbish mine.
John I know I now know what jet block I need, it’s just finding one
Well I got hold of another correct AG4 mag which has been rebuilt, I’ve fitted it and set the timing. I also fitted the Norton carb with the 206R jet block to se what’s it’s like and to be honest the engine starts and runs very well, also there’s no fuel spitting out, please note, I Havant cut or drilled the carb body. Air mixture adjustment is also working.
The only thing ive got to try and do is to stop the mag from slipping forward? I think the way Norton mags are mounted is a crap idea,
Lex says that the 'R' jet block works in an unmodified Norton body but I must admit that I can't for the life of me work out how. The block is a push fit in the mixing chamber and the pilot air inlet is completely obscured...Where does it draw pilot air from ?
I don’t know Rik, the air ports or pilot feed holes on the back of the jet block do seem to line up, Maybe it’s still some how getting air through the front, I’ve also got the Norton filter fitted.
Well I got hold of another correct AG4 mag which has been rebuilt, I’ve fitted it and set the timing. I also fitted the Norton carb with the 206R jet block to se what’s it’s like and to be honest the engine starts and runs very well, also there’s no fuel spitting out, please note, I Havant cut or drilled the carb body. Air mixture adjustment is also working.
The only thing ive got to try and do is to stop the mag from slipping forward? I think the way Norton mags are mounted is a crap idea,
Thanks, Barry
I am surprised - I have never had a problem with a Norton mag slipping forward or backward for that matter. Four screw fixings to the plate and a bolt and locking threaded screw between the engine / gearbox plates works fine - well for me anyway.
If anything moves that shouldn't then it is usually the gearbox especially if the tension adjustment bolt is broken through the gearbox top bolt and I have had that happen once requiring a piece of wood to be hacked out of a fence and wedged between the gearbox and engine / gearbox plates to get me home.
If the magneto is slipping forward on its platform then surely the mag chain is set too tight?