Norton Model 7 1953 NON STARTER

Hi all, this is my very first post and I need some help. My Dommie just suddenly stopped running and nothing that I do can get it to run. I've checked the gap(10-12 thou), I've taken off the timing cover and wedged the Auto advance mechanism fully advanced. I installed a TDC indicator (one that I use on my Triumph), marked TDC and then marked 1/4 down the stroke. All I get for my trouble is a small backfire. Any advice is sought and most welcome

Welcome here - although not under such circumstances. !
This problem didn't show after you'd been parked down the pub - and your 'mates' swapped over the plugleads ?

Seriously though, you sound as though you suspect the timing has slipped. Did it need readjusting ?
1st thing to do with all such cases is to try a NEW set of spark plugs.
Amazing what this will fix - if they are fouled or sooted, no amount of anything will make them return to life.

Failing that, checking everything else is probably on the menu.

Got fuel, its getting to the carb, and can be tickled.
Got compression, when you kick it over.
Strong spark on the plugs, when you remove them and lay them on the head, lead still attached.

If still no joy, remove an exhaust rocker cover, and verify the exhaust rocker(s) still go up and down.
And check rocker clearances.

I'd put money on those spark plugs.
But still check the plugs leads are on the right plugs.
Magnetoes can go duff with little or no warning, points can be dirty or oiled, etc.

Good luck, tell us how it goes, or ask away - and what fixed it.

BTW, the timing should always be set by ALWAYS rotating the engine forward, in the norrmal direction of rotation.
Turning it backwards at any point can allow all the backlashes to accumulate, and the timing can thus be way out...

Rohan's advice is all good, and in good order. As Rohan says, magnetos have a reputation for sudden crap out; usually because their capacitor (condenser) goes bad suddenly. Should this happen, no spark. Check if you are getting a spark with the plug laid against the head.

New plugs & no spark, I would lay the blame on a capacitor.

Slick

Additional information on what had occurred when it "just stopped running" might focus the approach. Everything Rohan said is correct but if for instance.

It just stopped running when:

- I was riding down the road. Would point toward timing slipping - especially if it just died with maybe a few exhaust pops. If it hestited, stuttered a few times and then stopped - points toward a fuel issue.

- the bike had been running fine on a hot day and you stopped at a shop for 5 minutes and then would not start again - that points to a mag condensor - especially if it has been becoming hard to start for a while.

- or if the bike has been parked up for a month or two especially in a damp place and wont start - points to again mag but also water in fuel, spark plugs etc.

Thanks to you all for your suggestions, it's currently 7.37 PM Sydney time, so first thing tomorrow morning I'll go down to the bike shop and buy a new set of plugs, wish me luck. I'll let you all know the result tomorrow.

Well it's been nearly a week since my first post. I went and got two new plugs (B5HS), then the weather turned lousy very cold . They called it an Artic vortex , coldest day for 15 years here in Penrith, although it's mid winter. I managed to retime the motor three moretimes with out any luck.
I've pulled off the oil bath and exposed the crankshaft, to mount my timing dial on, but first I have to turn up a screw on brass mount(on my lathe) to hold the timing dial on the crankshaft and hopefully get it right here's hoping.

Does the magneto spark strongly though, on both cylinders ?
Without the degree wheel, its possible to put a pencil etc down the plughole and get it reasonably accurate.
(be careful with the pencil though, if it breaks off or drops in, its trouble).

Failing all else, can just time it at TDC at full retard.
Shouldn't be ridden far or fast like this though.
Not good riding weather !

If its got a timed spark, good compression, fuel, and correct valve timing - then it has to go.
Tried a half teaspoon of fuel down a plughole, see if that kicks it into life.
If it does, its fuel related.
Hopethishelps.

Lay a spark plug against the head and with the other plug removed, you can push the kick lever with your hand, If the magneto is strong, you will get a spark with an audible snap or click. You can re-time until the cows come home, but if no spark this way, no joy.

If you have a good spark, then proceed with timing.

Slick

Well I'm back, it's been a week or two and finally some good weather(sunny and warm). The Dommie now runs like it should, sounds great. The problem turned out to be a very small slip on the taper drive, which resulted in a rotation of 1-2 degrees (roughly). Once I re-timed the engine it sprang into life and made me a very happy fella. Thanks to everyone who had their say,with numerous suggestions on what it could have been, very much appreciated.

When I got my Model 7, the spark timing was out by at least 20 degrees, and it still ran !
There wasn't actually much holding the maggie together either, but thats another story...
Good that you got it sorted.

Re original post; “Hi all, this is my very first post and I need some help. My Domie just suddenly stopped running and nothing that I do can get it to run”
I suspect that it was not the timing that slipped, even if it was a couple of degrees, I fear it will cut out again, when hot, the first thing I would do is check for spark- it may be condenser trouble. But I hope I am wrong.

Bernhard said:

Re original post; “Hi all, this is my very first post and I need some help. My Domie just suddenly stopped running and nothing that I do can get it to run”
I suspect that it was not the timing that slipped, even if it was a couple of degrees, I fear it will cut out again, when hot, the first thing I would do is check for spark- it may be condenser trouble. But I hope I am wrong.

Click to expand...

I agree. A few degrees is not going to stop it. As Rohan said his one ran (badly) at 20 degrees out.

The OP never answered the questions I suggested (or anyone else's either) so he isn't giving us much to work with. But mag is a good bet.

johnm wrote". I agree. A few degrees is not going to stop it. As Rohan said his one ran (badly) at 20 degrees out.

The OP never answered the questions I suggested (or anyone else's either) so he isn't giving us much to work with. But mag is a good bet.

+1 on the first sentence.

Re: the second sentence ... it is somewhat of an affront to us who attempt to help and the OP 'er takes not the effort to say something

Slick

texasSlick said:

Re: the second sentence ... it is somewhat of an affront to us who attempt to help and the OP 'er takes not the effort to say something

Click to expand...

It seems to be common practice for such problems to be plastered all over the net !, when you watch.
Not saying that is the case here, but frequently nothing more is ever heard, so at least we heard back here.
Even if we are left guessing.

Hi Gav

Please don't be offended by my comments. I am a Kiwi but since I have a son in the Australian army and an Ozzie grand daughter I need to be polite to West Islanders these days

You are posting for the first time and my comment came from more than ten years of experience trying to help on these forums but finding in very many cases we cannot get to an answer because there are not enough facts or feedback supplied.

If a bike stops there can be 100 reasons. From the simple - its out of gas, my mates pull the plug leads off, to some multiple complex of bad connections everywhere, dried crude all through the carbs, poor timing, old plugs, mag etc etc etc. (and even occasionally actual mechanical failure )

45 years ago :-( I did have a bike stop because the ignition timing slipped. I remember it very well I was passing a car on the Desert Road in the middle of the North Island of NZ. The bike suddenly slowed, the exhaust emitted a few pops and when I came to a halt the engine was as dead as a door nail. I had spark, fuel but when you kicked the engine over it had that totally dead feeling . The timing had slipped a good 90 degrees. Bikes will run (badly) with the ignition 20 degrees out so 2 degrees should not stop the bike.

I raced Norton Dommies for more than 10 years and 2 degrees is easily within the range you would test on a race bike to find the optimum ignition setting. If you read Paul Dunstal's Norton tuning book he suggests a range like that for 750s to allow for variations in fuel, compression ratio and operating conditions.

In my experience the only way to get there is to be systematic. There are people on here who know a lot. But facts to work with are what gets to the solution fastest.

John

We also didn't hear if the bike stopped on the road someplace,
or after sitting in the shed for an undetermined time.
That makes for rather different scenarios, and diagnosis ?
We can just hope it keeps running happily, they are uncomplicated jiggers.

Thanks John for your input re this problem with the bike. It just happened like I said, pulled up in the drive way after a quick blip around the block and it stopped dead. I gave it a few kicks but not even backfire out of the bike. I must have retimed it at least 6 or 7 times but to no avail. I fitted my Triumph TDC indicator and the degree wheel to right hand end of the cranshaft and did the setup according to the Norton manual for 1953)that I have. This resulted in a backfire, so I knew I was close, so I retimed the engine again taking more care with the dial (no paralax error).
It even took three days of trying to get the auto advance unit to free itself off the taper (the last thing I wanted to do was to damage it). I blame my self for that because I'm a believer in making sure everything is tight. I'm only guessing with regard to the amount of degrees of slip on the taper but to me it was very little, maybe 20 but it didn't look like it to me.

Gav

GavSull said:

pulled up in the drive way after a quick blip around the block and it stopped dead. I gave it a few kicks but not even backfire out of the bike. I must have retimed it at least 6 or 7 times but to no avail. I fitted my Triumph TDC indicator and the degree wheel to right hand end of the cranshaft and did the setup according to the Norton manual for 1953)that I have. This resulted in a backfire, so I knew I was close, so I retimed the engine again taking more care with the dial (no paralax error).

I'm only guessing with regard to the amount of degrees of slip on the taper but to me it was very little, maybe 20 but it didn't look like it to me.

Gav

Click to expand...

Hi Gavin,

Interesting. Usually you have to be accelerating hard or changing the engine rpm rapidly to get the timing to move. Maybe you have found the root cause. Time will tell.

By the way we should have added. - If you suspect the timing has slipped then use valve grinding paste to ensure the sprocket is fitting onto the taper with a good interference. Lap the sprocket onto the shaft and look for a good even grey surface. It is also worthwhile checking the nut is tightening up onto the sprocket properly and not hitting a shoulder somewhere.

Hope it all keeps going.

Here a video of my 1956 Dommie. # 500

https://www.youtube.com/watch?v=TyekqMox4tw

I think there might be other problems here;
Re; “It even took three days of trying to get the auto advance unit to free itself off the taper (the last thing I wanted to do was to damage it). I blame my self for that because I'm a believer in making sure everything is tight. I'm only guessing with regard to the amount of degrees of slip on the taper but to me it was very little, maybe 20 but it didn't look like it to me.”
The timing should be set with the advance/retard jammed in the OPEN position-you should jam a suitable nut into the A/R for this.
Also try this, remove mag and use a couple of small dollops of valve fine grinding paste on the taper and fit a/r and slowly move backwards and forwards till you have a matt shine where the a/r taper fits.
Having done this, clean all the grinding paste off as you don’t want any of that in your engine.
Also whilst mag is out check that the points gap is equal on each side with the same feeler gauge, and then fit the 2 spark plugs and ground to the body with tape ( or another pair of hands) and check in a dark room while you spin it for a healthy spark.
P.S I do hope you have the parallel twin magneto and not a V twin magneto (these have different points rings)

Dam –just found out johnm has beaten me to it :!: :shock: