Norton jubilee no pull.

Have you checked the screen on/in the petcock.

It might be plugged up but letting enough fuel through to fill the carb over time but not letting enough through for any engine speed above idle.

Mike

So many things it could be! When you say it stops does the engine simply stall or will it pull away with lots of revs and clutch slipping? Does it rev nicely in neutral, can you push it in gear so the engine turns over (ie the gearbox hasnât locked up!) is this a new fault, was it working ok before, what have you done to it etc etc!

Remember they were never torque monsters!

Make sure you clean the pilot circuit thatâs usually one of the first to get blocked.

Previously colin_ross wrote:

Previously Dan Field wrote:

So many things it could be! When you say it stops does the engine simply stall or will it pull away with lots of revs and clutch slipping? Does it rev nicely in neutral, can you push it in gear so the engine turns over (ie the gearbox hasnât locked up!) is this a new fault, was it working ok before, what have you done to it etc etc!

Remember they were never torque monsters!

Hi Dan, it will only pull with a lot of revs on it and it stops when the clutch starts to bite. The previous helper said about the petcock which we found dirty and the carburettor. I took the amal carburettor off it and it was very dirty so I cleaned it all and put it back on. It runs but won't run very well so I must have done something or it needs the carb reset. Thanks for your help, cheers.

Hi Colin,

If it starts and runs but does not have enough power to move it's own weight, then this is a classic sign of a dead or missing condensor. Are you still on points? If so, look at the points and see if you get a lot of sparks from them. Then, replace the condensor.

Regards

Tony

Yep 90% of carb problems are electrical, and vice versa! ð keep plugging away, youâll get there. I had similar problems, in my case i was supplied with the wrong sized carb (concentric) from Surrey cycles, after fitting a new monoblock it was sorted except now itâs leaking gearbox oil like the Torre Canyon! .... the joys of owning a 50 year old bike!

Colin, just a thought, all the spares to rebuild your Monobloc are available through Burlen Ltd or the NOC shop but it is very easy to spend more than the price of a brand new Amal and end up with a less than perfect carb! If the one on your bike is looking tired and wont respond to cleaning and setting up it might be better to buy a new one to more or less guarantee solving all your carb problems. Unfortunately a quick look at Burlen's web site shows the correct new 25/32" Amal 375 price £166.85 inc VAT) is temporarily out of stock but a phone call (01722 412500) will soon tell you when they will be available again and there are probably other suppliers! Mind you as Dan says above 90% of carb problems are electrical so a methodical check through the ignition system, particularly points, condensers and coils can only pay dividends (all available new from NOC shop at sensible prices) - particularly on a Jubilee! Good luck - ignore all the critics, a well fettled Norton Lightweight is worth all the hard work!

Nick

Previously Dan Field wrote:

Yep 90% of carb problems are electrical, and vice versa! ð keep plugging away, youâll get there. I had similar problems, in my case i was supplied with the wrong sized carb (concentric) from Surrey cycles, after fitting a new monoblock it was sorted except now itâs leaking gearbox oil like the Torre Canyon! .... the joys of owning a 50 year old bike!

The Torrey Canyon sinking was a good while back - I am guessing it was 1967 as I had just moved from London to Leeds; anyway it is impossible to permanently stop the early lightweight gearbox leaking oil without a major redesign of the oil seals. My Standard Navigator was totally oil tight all last year but over the winter for no known reason it started leaking gearbox oil again. It keeps one occupied.

I think the stalling problem is most likely related to the carb. Does the engine rev up properly when testing on the stand? Condensers can fail in all sorts of ways but if it is running properly on the stand then they seem less likely a suspect. I assume you are aware that you can mount the condensers close to the coil rather than the standard fiddly mounting in the points housing.

Patrick

I don't have any direct knowledge of the Jubilee, so I'm stepping on thinnish ice,but...

With their very short stroke, the Jubilee is very badly affected by imperfect ignition. A small inaccuracy in the timing is easily compounded if the atd is worn... People report that they respond VERY well to electronic iginition.

Paul

Paul is absolutely right Colin, timing is particularly critical on the Jubilee and has to be set very accurately at 30 deg BTDC fully advanced. This is a rather fiddly procedure and I strongly recommend getting the outstanding Twin Cylinder Manual for the Norton Twins 1957 to 1970 (ISBN 1-58850-069-1) or at least the original Jubilee & Navigator Maintenance Manual & Instruction Book. They tell you everything you need to know about maintaining and rebuilding the bikes and are available as photocopies from the NOC shop or from Veloce Press as a more robust paperback. If your auto advance retard mechanism is worn out a long term solution is electronic ignition but you will need to do some quite major re-wiring and a conversion to 12v electrics. Expensive but a better long term solution by all accounts. Specialist advice available from Andy Sochanik the club Lightweight technical expert and Al Osborn electrical expert - you will find contact details by following the Technical on the club home page. Good luck!

Nick (PS....my Navigator is still running happily on points and 6v so it can be done!)

Previously patrick_mullen wrote:

Previously Dan Field wrote:

Yep 90% of carb problems are electrical, and vice versa! ð keep plugging away, youâll get there. I had similar problems, in my case i was supplied with the wrong sized carb (concentric) from Surrey cycles, after fitting a new monoblock it was sorted except now itâs leaking gearbox oil like the Torre Canyon! .... the joys of owning a 50 year old bike!

The Torrey Canyon sinking was a good while back - I am guessing it was 1967 as I had just moved from London to Leeds; anyway it is impossible to permanently stop the early lightweight gearbox leaking oil without a major redesign of the oil seals. My Standard Navigator was totally oil tight all last year but over the winter for no known reason it started leaking gearbox oil again. It keeps one occupied.

I think the stalling problem is most likely related to the carb. Does the engine rev up properly when testing on the stand? Condensers can fail in all sorts of ways but if it is running properly on the stand then they seem less likely a suspect. I assume you are aware that you can mount the condensers close to the coil rather than the standard fiddly mounting in the points housing.

Patrick

Mounting the condensers up by the coils is NOT the thing to do. Yes it does work BUT the condenser is there to reduce the points sparking/burning, if you fit it by the coil the bit of wire down to the points now 'gets in the way' so you still have some increased sparking. Yes it works but not as long term reliable as putting the condensers where they should at the points. Cond. for the JUB, Navy, even the Electra can be hard to find that fit. Some years ago I had this problem all I could get was car condensers with no bracket so I unsoldered the brackets on the original cond. and resoldered them carefully on the car ones. It worked very well, I then fitted Boyer Bransden ignition, haven't touched it since. Unfortunately the BB does like its voltage high and the electric start does use it up. Hence unless you keep a good battery the electric start doesn't.

Hi Al,

The reason I am in favour of remote mounting is the fact that you can use car type condensers which are very cheap- a couple of pounds each- and work well in practice. I use MGB ones as I have these already as spares.

Mounting the condenser by the coil was common Japanese motorcycle practice as far as I know; certainly used by Yamaha on the four strokes in the 1970's before they went electronic. Also it was common works rally practice on the Cooper S and others to mount a spare coil and condenser in the engine bay so you could very quickly swop wires over in the event of any ignition problems on stage - lost time maybe 20 secs.

So I was only copying what was supposed to be 'best practice' as I am no expert on electrics.

Patrick.

Colin, great advice from Al. Luckily the NOC parts team have new condensers, points and coils in stock which fit in the original position perfectly. When I got my Navigator the previous owner had mounted car type condensers up by the coils which seemed to be working fine but the tick over was erratic and it suffered the occasional miss fire / hesitance in the mid range - all symptoms of carb and electrical faults and wear. I rewired the bike, replaced the points and condensers in their original position, re-timed it and rebuilt the carb and it now starts first kick, ticks over and runs smoothly with none of the original problems and performs as advertised. That said I know it will require regular maintenance to keep it that way. When I do come to a rebuild I will look very carefully at 12v and BB ignition conversion for really accurate timing, smoother and better performance and carefree maintenance......I hope! Good luck with the Jub'!

Nick

If Colin hopes to "pull" on a Jubilee then I think he will definitely need to ride it back to 1967 and hope to meet a nice "dolly bird" (although even then Jubilees were sadly under-appreciated).

Previously patrick_mullen wrote:

Previously Dan Field wrote:

Yep 90% of carb problems are electrical, and vice versa! ð keep plugging away, youâll get there. I had similar problems, in my case i was supplied with the wrong sized carb (concentric) from Surrey cycles, after fitting a new monoblock it was sorted except now itâs leaking gearbox oil like the Torre Canyon! .... the joys of owning a 50 year old bike!

The Torrey Canyon sinking was a good while back - I am guessing it was 1967 as I had just moved from London to Leeds; anyway it is impossible to permanently stop the early lightweight gearbox leaking oil without a major redesign of the oil seals. My Standard Navigator was totally oil tight all last year but over the winter for no known reason it started leaking gearbox oil again. It keeps one occupied.

I think the stalling problem is most likely related to the carb. Does the engine rev up properly when testing on the stand? Condensers can fail in all sorts of ways but if it is running properly on the stand then they seem less likely a suspect. I assume you are aware that you can mount the condensers close to the coil rather than the standard fiddly mounting in the points housing.

Patrick

I take the point that condensers can be at the coil BUT I wouldn't do it anyway, electronic....

The other item up here is that TR says that if it 'starts well but fails when under some load then it could be condensers' can't agree. The condensers are there to reduce points burning/arching and they increase the efficiency hence voltage of the spark. You always need most when starting so duff condensers will reduce starting efficiency.

Colin:

I am not familiar with the Jubilee but I wonder, does the pionts/distributor have a flyweight assembly that advances the timing as the revs go up?

If so, maybe the flyweight assy is stuck??

Mike