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Fuelling issues

The saga continues,

the 961 street has returned from the dealers after nearly 3 weeks, guess what. The first ride out and the problem remains. It ran fairly roughly until warm and then wouldn’t slow down until a prompt from the brakes . At the first stop after 25miles it wouldn’t tick over at anything less than 3000rpm. Turn the ignition off, start the bike up and it ran perfectly well for the rest of the run!!!!

Back to the dealers I guess.

have fun 




Guess. There is precious little chance of diagnosing a fault like that unless you can interrogate the ECU and Norton wont release the access code. That also prevents a third party from making a diagnosis. My understanding is that this is technically illegal as BMW found out 5 years back.


My 961 expired and took the factory so long to fix that I lost a bucket load of cash in terms of Insurance, Road Tax, Warranty and value of the bike itself. Most annoyingly, my plan had been to ride the bike until month 10, then sell it so giving the next owner 2 months of the full warranty. When the first year of warranty expired, with the bike still at the factory, I asked for this to be extended for the reason mentioned above. No prizes for guessing what the factory said.

On my 961 the first year warranty covered the whole bike but the second didn't. I wonder if this is why you see so many 961s for sale after just a year of ownership?



it could be anything with these bikes - for a simple push rod twin, it ain't half complicated!

Mine went back on Month 11 of the first year as the EML came on, at Norton for 2-3 weeks to sort issues and requested 12mth service; issues were Lamda sensors (replaced), cracked/broken wire to the throttle position sensor (wire replaced) and a leaking gasket (replaced) quote from technician - "somewhere in the bottom of the engine case".  Collected on 12th August and proceeded to ride home and the bike started misfiring above 4000 rpm. Eventually cutting out at 70mph as I was overtaking an articulated lorry.....

Back to Norton.... on 13th August and eventually, after speaking to warranty manager, was informed ECU dead and causing issues so replaced.  Bike coming back on Wednesday 11th September.

Why so many up for sale after one year?

1) Issues coming up and warranty running out - 2 years but some exceptions after year 1

2) Issues could become a problem on the road!

3) Owners want some return on their "investment" while the bike still actually runs?


I guess I must be one of the lucky ones then, 14,000 miles and still going strong . Maybe the 'old girl' new I was going to keep her for ever and not sell her off after ten months and said to herself "I like this man and we are going to get along just fine" :) .


Hi all, I've investigated this issue at great length. Using wide band oxygen sensors to see what was happening at idle. After much testing I was able to discover the root cause.

When the engine is at idle the throttle body butterflies are essentially closed and air is supplied via the Idle Air Motor. This is a little stepper motor that opens and closes on command from the ECU to finely adjust the airflow to achieve the target rpm. The air is supplied to the engine via a shared pipe between each throttle body in front of the throttle butterflies.

With a wide band oxygen sensor in each header pipe I was able to monitor the air fuel ratio (AFR) in each cylinder. I discovered that cylinder two was stealing charge from cylinder one at idle rpm via the shared idle air pipe. As I have fitted a programmable ECU to my bike I was able to adjust the amount of fuel to individual cylinders. If I added fuel to cylinder one which was lean, cylinder two got richer and cylinder one stayed the same (and no the wiring was not crossed over)! Now on a standard bike the ECU gets information on fueling via the two narrow band oxygen sensors located in each header. From the ECU's perspective, it see's cylinder one is lean and adds fuel, cylinder two is rich so it cuts fuel. The ECU frantically adds more fuel to cyl. one and cuts from two. Around and around it goes until it reaches its programmed limits (generally around 20% extra or less fuel). The end result is an engine that struggles to idle if left to long at idle fouls the cylinder two plug.

After much experimenting I ended up with a very simple solution. I removed the entire idle control system and plugged the shared pipe that was causing all the problems. I then adjusted the throttle position screw so the engine at stone cold would idle at the lowest possible rpm so that once it warmed up the idle wasn't stupidly high. What I discovered was a bit of a revelation, the engine is actually perfectly happy to start and idle from cold at around 750rpm, far below the the factory 1,250. Once fully warmed up it sits at around 1,200 perfect.

I also removed the narrow band o2 sensors as I felt the PID controller (a mathematical algorithm that tries to predict what the ECU has to do to correct the fueling based on the o2 sensor input), needed work and was contributing to the idle hunting problem. This is because the ECU needs to swing the fueling rich and lean to get the catalytic converter to work properly. If the algorithm is not spot-on then the AFR can swing too far and the algorithm essentially loses control. I know all this because I could switch the o2 sensors off and on in the ECU and see the result.

Here's the proof.

Note: the numbers on the display are in lambda. Lambda 1 = AFR of 14.7:1. Less than 1 is rich more than 1 is lean. Part way through the video I add and subtract fuel from individual cylinders to confirm the fix. At idle I find the engine is happiest running a touch rich around .95 lambda or 14:1.

Lastly to prove just how good this engine can be at idle. Here's a cold start in winter, notice how happy the engine is to start and settle into a stable idle at well below the factory 1,250!

I did all this work over last winter (northern hemisphere summer) and now that spring is here have got out and done 600 or so km. Engine has started and idled perfectly every time hot or cold!

Also fixed the oil in the airbox problem - which ironically involved removing the factory sticking plaster fix!

So I've ended up with the entire idle system deleted which has resulted in... a perfect idle. I've removed the ugly air/oil separator box and oil collection bottle and put my own system in place (nothing goes into the airbox). Here's the result.

Norton Dominator SS finished







I would think that the Factory needs to hire you on a consultantcy basis to get their fueling system problems ironed out!


Peter....there were so many niggly problems with my 961 that I could have filled a book with the details. In fact I still could as I kept a very detailed diary which eventually hit 20 pages of A4 size text. The problems which included engine management, numerous electrical issues, very bad vibration at 70 mph, corrosion, loose rear wheel spokes and a leaking fuel tank being just some. 

The bike would start and idle each morning but then cut out at every junction for the next 2 to 3 miles. It was unpleasant to ride in slow traffic with a continuous jerking, juddering or snatching. To solve these problems the service agent set the idling to 1200rpm. This rose to 1500 when the engine had warmed up making selecting any gear very difficult.

In wet weather, when riding at motorway speeds, a whole bundle of problems would occur. The vibration would cause the light switch to operate on its own. Generally switching the headlight off. The same vibration would continuously shake my right boot off its footrest unless I rode at 60 or 80mph.. The speedometer trip meter would start to go backwards and the headlight bulb would probably blow. I think I replaced five of these altogether.

The servicing dealers had problems getting replacement parts for this bike due to the changes of suppliers and specifications. By the time the Factory became involved in trying to sort out the lengthy list of issues, two sets of wiring, regulators, rectifiers, speedometers, sensors, oil pumps, breathers and associated separators had been fitted. People kept telling me to expect teething problems with such a new model!!!


While I can't speak for all of the dealer network, many have no clue and will try random things in the hope the problem will go away.

Regarding your idle Philip, as I explained the ECU relies on the narrow band o2 sensors for fueling information. BUT when you first start the engine the ECU ignores the o2 sensors input as they need a couple of minutes to heat up first. Until that happens the ECU just delivers a pre-programmed amount of fuel. This would explain why the bike started ok, but turned to rubbish not long afterwards.

I had all manner of niggles and the bike spend much of the first couple of years at the dealer. They had no clue and did as much damage as good. The factory meanwhile was trying all manner of fixes to sort the oil in the air box issue. I broke down on a few occasions mainly due to relays falling out due to crazy design of the fuse/relay box. The cover is not latched down and can easily spring off with vibration. So you need to cable tie it shut. Someone posted a picture to the Norton 961 facebook group the other day of their visit to the factory. Low and behold it would appear a cable tie around the fuse box is now a factory option!

Cable tie on fusebox

Now if I knew back then what I know today, I could have sorted the bike out in about half an hour! I don't think the necessary checks and balances are in place to ensure each bike that comes of the line is fit for purpose. Only last week I replaced both tyres and discovered the front axle had never been greased and was covered in surface corrosion, others reported their axle's were greased - I'd be tearing my hair out if these were my staff. One bit of individual carelessness can have far reaching consequences for the brand.

If the throttle body design was changed slightly one of the major problems would go away. Norton has seen all my videos and initially suggested it was an engine map issue. Once I had proven beyond doubt it wasn't they went very quiet. They've continued to try and use software i.e. the engine map to get around what is a mechanical problem. As to why it continues this way only Norton knows. I could speculate and give you half a dozen reasons as to why, but what's the point. They have my email address and I know they read all the posts both here and on AccessNorton.


Sounds like the dealer has messed around with the throttle position screw. That’s the only physical thing they can touch since the ECU is locked. By messing with the screw too much air is getting in and the ECU can’t bring it down when warm (the screw opens the throttle butterflies). The snatching behavior possibly indicated that the throttle position sensor needed to be reset.

Permalink follows are the details of the first couple of rides on my new 961. The bike was delivered in the middle of a heavy rainstorm. I understood, from the dealer, that he had test ridden the machine the day before ......also in very wet weather. Each time that I rode the bike it was hand washed, towel dried and the shiny chunks sprayed with WD40. Like yourself my 961 had a seriously rusty front wheel spindle and a rear one that looked like it had been stored in a pond. The latter having delaminated in its hollow centre so badly that the spindle hole was full of flakes of rust. I asked for both to be replaced under warranty , suggesting that surely the integrity of each had been compromised by the corrosion. This request was turned down flat and I was charged extra for removing and servicing the spindles. The first service bill included extras I did not expect to have to pay for including £90 for the oil change. At this first service I was informed that my 961 needed a mod to fit a breather oil separator. The Agent had none in stock and I had to return a few weeks later for the fix.This separator was fitted free but I was charged for another oil change. The first 3 months of ownership cost me over £500 in servicing fees and travelling expenses. At the same time if you purchased a new Honda or Triumph, the first service was free.  Attached pictures show the bad news after just a couple of months of ownership.

03/12/2015      Bike delivered at 2.30pm.  Looks good but one exhaust is bright blue already courtesy of a Thor pre-delivery test ride.  After signing off all the relevant paperwork the deliveryman rapidly disappeared. His only words of advice being that ‘they don’t handle very well on Dunlop tyres.’ Which of course it has fitted. I go and start the bike ready for my own test ride.

                        The engine is very, very noisy and lumpy at low revs. I set off down the road and the bike cuts out at the first corner and the second and the third. I check the fuel level and cannot see any. So presuming that low fuel is causing the problem, head off to the nearest petrol station.  I top up with 10L of unleaded and then head off for a 30 minute ride over hills and round the back lanes of Porchester.  The low rev lumpiness continues and the engine sounds as though several people wielding lump hammers are whacking it. There are also horrible vibes between 4 and 5 thousand RPM. In my opinion, having owned 6 Atlas’s, I would say the 961 was as bad as the worst of these. 10 miles added to the clock. Bike then locked away due to bad weather.

                       Read through the Rider’s Handbook.  It has 116 pages of which 34 are totally blank and tell you so with the statement, ‘This page is blank’ on each of them. They are also quite a few ‘nearly blank’ as well as plenty that inform you about the warning stickers that adorn the bike.

08/12/2015      Run number two. Check bike over and notice rear chain with large patches of rusty sideplates. The road is still damp from the mornings deluge but I head off to briefly challenge the M27 motorway. The engine started easily, once again, but as before died at the first junction. This time, the ride was a mix of hills and long flat roads. The engine pulled happily up to 65MPH at just over 4000RPM.

                        20 miles later I returned home and followed the procedure for an oil check. Shock horror here when the dipstick showed the oil level as 3mm below the min mark.

                        Now thanks to my previous collection of bikes, I had a stock of unused pots of oil from every big name manufacturer. The 961 handbook insisted on Silkolene 10w/40 semi-synthetic as its one and only lube. Which of course I did not have. I had both Mobil and Castrol versions of this oil but not Silkolene.


Going a bit off topic now. I just think Norton got caught out in the belief that if you hand build a motorcycle it will be of a higher quality than a mass produced equivalent. As they've discovered nothing could be further from the truth. In addition with very little institutional knowledge to fall back on with regard to the do's and don'ts they've discovered a lot of design decisions have not stood the test of time (which more road testing would have discovered). Not helped by some pretty poor support at the dealer level.

This is the state my bike returned to me in after a trip to the local dealer. They managed to snap off both the ECU mounting lugs and figured stuffing some packing foam in would do the job. Even a backyard cowboy would think twice. Yet this was an official dealer working on a very rare and very expensive motorcycle!

I'm not surprised many owners just gave up and moved on. Your experience while not universal was far to common and many potential sales have been lost as a result.

Packing foam under ECU


The dealer should be named  and shamed and the pictures sent to R.G. at Norton , not that they would take any notice though :(


Ian has highlighted an issue that was also a problem with my 961. At the major service, when the seat was removed to check and change the oil & filter, the inside of the rear fairing looked as though a bag of flour had been tipped in the recess. The ECU was clearly floating around unthethered and vibration had done its worst. Possibly this was an explanation why the volt meter was showing now 14.7v at cruising speed and the main headlight  bulbs kept blowing.

While replacing the fifth blown main bulb that I had noticed the rusting headlight rim. I mention this during the bike's major service. One of the mechanics had the nerve to blame me for this happening. Apparently, I had failed to seal the rim with sufficient waterproofing goo while changing the bulb. This on a bike I had owned for just 6 months. As follows are the faults reported at the major service......

Both wheel spindles corroding

Both silencer brackets rusting

Corroded Brake reservoir screws + leak from reservoir seal.

Corroded Handlebar Bolts

Rusting Rear brake hose bracket

Rusting Headlight Rim

Flaking Stainless Steel Exhaust pipes

Rust spots on both silencers

While not life threatening issues, this 961 was sold to me as a quality product built for a niche market. Perhaps my understanding of the word quality differs from that of Norton salespersons. The list of faults had doubled before 2000 miles were on the clock. Including Rusting of  the fuel tank mounting bracket attached to the top of the frame. 



I would have expected some replies to the postings about a shoddy product being produced but perhaps they are too busy doing a  brewup to take notice???



It's sad but the issues all seem to arise from emmision standards becoming so nearly impossible to achieve that it has become impossibly expensive for any but the huge global manufacturers to enter the market. When I look at a 1930's Norton single, it's hard for me to see what could be improved (apart from an electric start, and perhaps the oil leaks...).

But the fact that a feedback system can oscillate out of control causes problems everywhere it exists...from adjusting the hot vs cold shower in the bathroom to suffering a banking crisis like 2008.

This was not the dealers worst bit of workmanship. Hard to believe I know!

When the oil in the airbox issue was at its height, the dealer decided to attempt to raise the height of the air filter inside the airbox to stop the oil that was pooling on the bottom soaking the filter and dripping out (air box entry is on the bottom in the Dominator). To do this they trimmed the base of the air filter so the base would fit inside the airbox and simply covered it in some kind of sealant to glue it in! No idea how long it lasted but I discovered it dangling half out of the air box. Who knows how long the engine had been breathing unfiltered air for...

Air filter



Norton were actually quite helpful in resolving a lot of the issues I had, so please don't bag them for dealer incompetence. Although these issues really should have been caught before the bike went into production.

Touch wood, my bike is a joy to ride now. I never worry if it will start or idle. The engine feels and sounds great and I still need to finish the ignition timing map.




A nice engine ruined by a bad calibration. 

I run mine with a decat and lambda sensor blanking plugs and Standard silencers. Runs fine and has lost that fluffy power delivery between 2700 and 3300 rpm. My 961 commando sport doesn't sound as nice as yours. You must have the "aftermarket silencer" calibration since you have all that wonderful sound. I think they made even more of a hash of the aftermarket calibration. My understanding is that there are only two calibrations "std" and "aftermarket silencer". 


And I thought reading various road tests by MCN (a trustworthy publication) and tests by the esteemed Alan Cathcart that these bikes were brilliant and the saviour of the British bike industry, just as I have almost raised enough money from regular saving for a deposit am I to understand they are not perfect  ?

Triumph engines are mechanically silent and have no such issues. Sorry, Mr Garner, it is your designers and production staff and absence of effective QA that are to blame.  A talented privateer  can design a far better bike. Seen it done time and again.


Oh dear Terry, inflammatory comments, expect a strongly worded letter, BTW, I have such a Triumph, excellent bit of kit but not as good as my Nortons (64-75) for the avoidance of doubt .


Didn't say "I could design it"; just saying that talented designers could. I met loads when I worked on ECUs for the Ford Motor Company. I just looked after their software design methods. I left the "talent" to do the real work. I just have a little better appreciation of what it really takes. 


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