Hi, New to Norton Ownership, with a Problem!

In the USA, the Mk II comes with a #50 enrichment aka choke jet. That's way to rich. If the choke is left on for more than 30 seconds, the spark plugs will begin to foul. I found that using a #35 allowed use of the choke for start up and the first 5-7 blocks, which was generally long enough to allow a normal idle with it turned off.

chaztuna said:

In the USA, the Mk II comes with a #50 enrichment aka choke jet. That's way to rich. If the choke is left on for more than 30 seconds, the spark plugs will begin to foul. I found that using a #35 allowed use of the choke for start up and the first 5-7 blocks, which was generally long enough to allow a normal idle with it turned off.

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Interesting. Does it still start fine on cold days (below 40F)?

Some of you may like the 'stay up' floats, but I took them out after days of fiddling and having problems. Went back to the originals and life is again good..... just couldn't get those damned things to work right, so backwards into progress for me. No hiccups now for 8 months.

Mart UK mine starts in 40F. Hard to kick over & takes more of a tickle, but catches and goes well after a bit of blubbering and complaining. 4-5 kicks at that temp( sometimes more if I flood it) and really doesn't care for the disturbance at all.

Mart UK said:

Interesting. Does it still start fine on cold days (below 40F)?

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It started and had good cold warm up running down to 20F. I didn't ride if it was colder than that.

1up3down said:

MART !

DO NOT let it idle too long on choke as it enriches the mixture and WILL foul the plugs
The choke IS ONLY for starting and literally within about 10 seconds increase the rpm with the throttle
while you take it off choke and you can maintain an idle of around 1500 while it warms up with choke off

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It's not a good idea to let the motor idle on startup in any event. Until the oil is warm and circulating idling destroys the camshaft. I keep the rpm at about 2000 until the engine is warm.

jbruney said:

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Mart UK mine starts in 40F. Hard to kick over & takes more of a tickle, but catches and goes well after a bit of blubbering and complaining. 4-5 kicks at that temp( sometimes more if I flood it) and really doesn't care for the disturbance at all.

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How do you "tickle" an Amal Mk II carburetor???

Not ll's, so on yours a mystery to me. Just get the fuel in there however because without ticklers I'd be lost and wondering.... Mine still lives in 1974.

johnm said:

It's not a good idea to let the motor idle on startup in any event. Until the oil is warm and circulating idling destroys the camshaft. I keep the rpm at about 2000 until the engine is warm.

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OK. I've not been doing that, so far. I am a bit hesitant to do that. 2000 revs with thick, cold oil, feels a bit brutal?

Mart UK said:

OK. I've not been doing that, so far. I am a bit hesitant to do that. 2000 revs with thick, cold oil, feels a bit brutal?

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I think the concern here is the cam doesn't get much oiling at lower idle rpm. I see some Norton riders in habit of blipping the throttle while at longer lights to keep some oil reaching the cam effectively. Personally I don't think its too big of an issue for road going bikes. Be sure to look at Jim Comstocks excellent testing of many oil brtands for best suitability in Norton engines (https://accessnorton.com/link-forums/norton-commando-oil-database.37/).

If it’s an older Carb toss it and get a new Mikuni. Best money spent

120 miles today . Only 7.9 litres of fuel , 1.75 UK gallons, 68mpg. Allowing for misjudging the level, still likely to be more than 60mpg. Took it relaxed to start, but some spirited riding in the middle. Less concerned about the tank size!

Couple of oil leaks, rocker cover gaskets and the jubilee clip just below the oil tank banjo. Possibly at the base of the primary case too.

Ran lovely, ticked over fine. Very pleased. Must remember to turn the fuel tap back on...

Thanks for your advice.

Mart

Glad to hear you're seeing the fruits of your labour. This is what makes these old bikes so enjoyable, being able to solve the numerous issues and get them out on the road again. Don't let the problems bring you down.

Long ride last week in the sunshine, on new tyres. Went beautifully. Today, it turned over fine on the starter, no spark at either plug. Tested with a spare, unused NGK. Nothing. Battery is recent and the voltage is good. Impedence tests, HT lead to each 6v coil and primary windings on each coil tested out fine. No sign of flex in the Boyer stator wires. Good voltage across battery to engine case and terminals are clean and secure. Kill switch hasn't been touched, but I switched it to kill, then back again, no change. The wiring loom looks good visually and easy to get to connections look fine. Even checked the two alternator wires from the primary for continuity, were fine. There was oil all over the gearbox neutral light switch connections and the connectors to the blue spring held (resistor?) under the seat (a weep from the return hose to the oil tank). I cleaned both up, just in case. I did notice a short white/purple lead, with a connector was dangling near the blue resistor, under the seat. Only about 2" long, nothing obvious to connect to. It's been too long since I last used a wiring diagram, but it suggested to me W/P for the coils? Is this a relic of the points original ignition wiring, no longer needed?

Tomorrow I'll check the in-line fuse near the battery (forgot to do that) and start looking into how to check the Boyer Powerbox, sited behind the coils and the Boyer EI. Don't want to jump to a conclusion they are the problem. Anything obvious (cheaper!) you think I should check first?

So far this bike is making me earn my fun!

Mart UK said:

I cleaned both up, just in case. I did notice a short white/purple lead, with a connector was dangling near the blue resistor, under the seat. Only about 2" long, nothing obvious to connect to. It's been too long since I last used a wiring diagram, but it suggested to me W/P for the coils? Is this a relic of the points original ignition wiring, no longer needed?

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Yes, it's the ballast resistor bypass wire that would've originally connected the solenoid 'I' terminal to the coils so the coils got full battery voltage during electric starting and which should not be connected to the solenoid or coils if electronic ignition is fitted.

The "resistor" spring mounted sounds like the 2 MU capacitor. There is a test for it listed in the workshop manual.
If you've got power to lamps etc then the one in line fuse is good. Certainly sounds like a boyer issue. Common problems are with pickup wiring at the stator plate (typically an invisible fracture under the insulation or at the board surface). Needs to be wiggled about while testing for open circuit or while engine running.

Though you cycled kill switch (does the MKIII have a toggled kill switch, mkII is momentary), it could be a poor contact. Try a bypass around it and see spark returns.

Tornado said:

The "resistor" spring mounted sounds like the 2 MU capacitor.

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2MC

Tornado said:

does the MKIII have a toggled kill switch,

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Yes, it does.

Tornado said:

it could be a poor contact. Try a bypass around it and see spark returns.

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Also, check the 4-pin plug (should be?) with the white and white/yellow kill switch wiring in the headlamp shell for corrosion, poor pin contact, etc.

I have 2 MK 111's. Eliminate the kill switch issue ( although others will disagree I'm sure ). Clean up EVERY connector involved with the ignition circuit and use dielectric grease on them .
Analogue old style voltmeter helps. Have your Boyer bench tested , or substitute a new one. I use substitution all the time and it works for tracings.

Torontonian said:

I have 2 MK 111's. Eliminate the kill switch issue ( although others will disagree I'm sure ). Clean up EVERY connector involved with the ignition circuit and use dielectric grease on them .
Analogue old style voltmeter helps. Have your Boyer bench tested , or substitute a new one. I use substitution all the time and it works for tracings.

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Kill switch works properly. In the gloom in my garage, I had assumed right was off and left on. Set up a better light to start taking the control apart and noticed the kill is 'killing' left and right. Doh! I must have knocked it when I washed the bike? Spark back and started 1st time. At least I've confirmed the W/ P wire is non essential and the coils are good, the timing is on the mark's in the primary and on the Boyer stator/magnet...

Time for a ride.