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I think my NC might be terminal - total loss of power


pmjones79

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Hello All
I have a 2012 NC700X that I use everyday (except extreme weathers).  I have looked after it as best as I can.  I try to resolve all issues as they arise but this week I have encountered a problem that I cannot solve.
I was taking my regular commute to work (about 13 miles) when I there was a drop off in speed and power.  I was travelling at about 60mph and the bike slowly dropped off to 50mph.  I pulled over and looked for anything obvious.  Nothing jumped out as obvious.  So I attempted to set off on my way.
Unfortunately, when setting off the bike had lost a lot more power now and struggled getting above 30mph.
The bike seemed to lose all torque.
I had to get recovered and my bike has been in my garage since.
I have been trying to investigate various things.  I have checked and replaced the spark plugs but no change.  I even went back to the old plugs and it is still the same.  I have checked the battery and it is great (not very old).  I have stripped all the plastics off to get to and test the ignition coils.  The resistances I am getting on the primary and secondary side of each are identical.
I have spark test device and when I plug that into the spark plug lead and fire it up I have a strong/long spark across it.
When I start the bike it starts fine.  Before it starts I hear the fuel pump prime.  It appears to rev fine and steady.  I put it into first and it still sounds fine.  When I attempt to pull off the bike makes all the right noises but pulls off at a snails pace with no torque.  It won't even ride up my very shallow ramp into my garage.
I don't want to just throw money at it, mainly because I cannot afford to do that.
I am swaying towards a fuelling issue.  Something like a fuel pump/filter or injectors.  I am not getting any fault indications on the dash/clocks though.
I wanted to ask you lovely people on here if anyone has experienced a similar issue and if so, how they rectified it.
Thank you in advance.

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Well, Thanks to all you wonderful people my bike is alive again. Today I replaced the clutch and it did the job. I am chuffed to bits that i finally got there. I had so much help from a

Do you have the "check engine" light on? If yes then find out what the fault code is.   Does it have oil in it?   Do the brakes get unusually hot? Can you push the bike easily in n

… there was an OP?

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ChrisCB

Not sure if this will help but I recently bought cheap 700 with a similar problem, it wouldn't pull the skin off a rice pudding. In these cases I always drain the fuel, replacing the fuel cured this one but I pulled the fuel tank anyway and it was full of some kind of sediment, now cleaned out and some fuel treatment run through it's as good as new.

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jeremyr62

A long time ago I had similar symptoms with a CB250N. Turned out to be a cracked valve which was serious. You could try compression testing it if you have access to a tester. 

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SteveThackery

Any odd mechanical noises or audible changes?

 

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Thank you all for the rapid replies.

It doesn't sound to like it is a happy bike at the moment.  One of the guys at work said it sounds like it is missing but I can't hear it.

Obviously it is something or it would still be running trouble free.

I hope it isn't a cracked valve but burying my head in the sand isn't an option.

I'll check the fuel tank first.  That seems like a quick win.

If not, then it is going to have to go into a garage.  Trouble is, there aren't any reputable bike garages around here without going to a dealer.

Dealers usually want mega bucks too.

AAARRRRGGGGGGHHHHHHH!!!!!!

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Do you have the "check engine" light on? If yes then find out what the fault code is.

 

Does it have oil in it?

 

Do the brakes get unusually hot? Can you push the bike easily in neutral (brakes not binding)?

 

Check the voltage at the battery when the engine is running, the battery might be good but if the volts go low when running it can upset things. You should see in the region of 14V running.

 

Check the airbox for foreign objects or blockages. The spout, filter etc. 

It is not unknown for rags or mouse nests to find their way in there.

Check the exhaust tailpipe doesn't have something stuffed in it, kids can have a strange sense of humour sometimes.

 

Check the throttle is actually opening, not the twistgrip but the actual throttle cable cam on the side of the throttle body.

Do a basic compression test. I'm assuming it's a manual. Put it in gear (1st or 2nd) and either try pushing it or if you have a centrestand do it on that and turn the rear wheel by hand. If you feel definite separate compressions then all is not lost.

The tips above regarding fuel are right. Have you recently filled up somewhere unusual? Did it start to play up shortly after refuelling? Does it perform OK when cold or is it bad at all times? If in any doubt get the old stuff out and add some good fresh fuel from a busy station (turnover of fuel), and if you use a can make absolutely sure it is clean before getting the fuel. I had to sort out a neighbour's mower 3 times before I eventually looked in the fuel can he was using to find about 1" of water in the bottom.

 

There are more intrusive things which could be checked of course, valve clearances for example.

 

 

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Andy m

Lots of good advice above. 

 

Terminal stuff tends to be just that, big bang, noises like rusty bolts in a tumble drier, then pedestrianism. 

 

This to me is one of the many annoying small things that can ruin your day. Fuel filter, TPS, exhaust sensor (although they bring a light on), bad earth, coil on the way.....

 

I'm afraid you have to observe, list the suspects and hunt deeper until you find it. If you've got a spark I'd be going fuel system next. 

 

Andy

Edited by Andy m
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I had some thing like this when my heated grip glue let go on the throttle side, even if i did not have the grips turned on five mins after take off the big would slow to a crawl.

Only needed to be re-glued..

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Definitely check for any blockages in the air supply

In fact, when was the air filter last replaced? Try starting and running the bike with the air filter removed 

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Is it revving free in neutral. I've had two similar issues on cars, one was low fuel pressure that I thought was the fuel pump but ended up being a blocked fuel filter - this was allowing the engine to rev but not pull. The other was a blocked CAT however this meant the engine would not rev past 4000 rpm

 

hope you get it sorted

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trisaki

Do a compression check , when were the valves checked  

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Grumpy old man

Just a thought,  you say it runs fine when until you try to pull away at this point does the engine still rev or does it die. I'm just thinking could it be a clutch problem ie. Clutch slip. 

Just a thought. Hope you get it sorted.

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Graham NZ

If the fuel pump assembly is at the top of the tank, (I'm not sure about that) checking out it's filters could be worthwhile.  Much easier than getting to the buried air filter, but it too could be the culprit.

 

From the service manual the fuel pump does look pretty typical.  There is usually an obvious and easily replaceable intake filter to stop grunge reaching the electric pump and a finer filter on the outlet side to prevent dirt getting to the injectors.  The fine filter is often only replaceable as part of the pump assembly.

 

Where is the fuel pump located, anyone? 

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Graham NZ

Yoiks!  Looks like access to the fuel pump and it's filters on these bikes is even more difficult than assess to the inaccessible air filter. Blimey!

Concern about tank internal rusting has prompted me to take the following measures to minimize the risk:

  • Try to refill the tank just before arriving home after any longish ride so that the tank will have as little moisture-laden air as possible in it for the moisture to condense into liquid water.
  • Every couple of weeks dose a full tank with the recommended volume of UCL.
  • Every few months add a half-cup of methylated sprit to a full tank so the meths will pick up any water and run it away during combustion.


One of the biggest concerns when buying used bikes, but especially old ones, is the risk of internal rust which can be difficult to spot. Even tanks made from coated steel can suffer from crevice corrosion where the tank top and bottom are joined.

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5 minutes ago, Graham NZ said:

Yoiks!  Looks like access to the fuel pump and it's filters on these bikes is even more difficult than assess to the inaccessible air filter. Blimey!
…….Every few months add a half-cup of methylated sprit to a full tank so the meths will pick up any water and run it away during combustion.

 

Indeed, the tank is tucked away well!

The usual stuff to use for de-watering petrol is iso-propyl alcohol, or IPA. It's what is used for carb icing prevention additives, it attaches to water molecules and prevents ice crystals forming. I don't know what availability is like in different markets, but in the UK it can be got in industrial purity in bulk from the auction site, something like £3/litre or similar if buying 5L for example. It is much cheaper than the proprietary anti-icing additives, but it is essentially the working ingredient.

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Graham NZ
20 hours ago, embee said:

Indeed, the tank is tucked away well!

The usual stuff to use for de-watering petrol is iso-propyl alcohol, or IPA. It's what is used for carb icing prevention additives, it attaches to water molecules and prevents ice crystals forming. I don't know what availability is like in different markets, but in the UK it can be got in industrial purity in bulk from the auction site, something like £3/litre or similar if buying 5L for example. It is much cheaper than the proprietary anti-icing additives, but it is essentially the working ingredient.

How much would be sensible in the NC 14litre tank?

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You beat me to it Graham.. or how much per Lt of fuel?

Lyn.

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Scootabout

I imagine once the OP has investigated all these suggestions he'll get to the bottom of it. Out of curiosity, though, does the NC's ECU have a 'limp home mode', like some cars?  

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5 hours ago, Graham NZ said:

How much would be sensible in the NC 14litre tank?

The usual rate is 1%, or perhaps up to 2%, as here https://www.silkolene.com/motorcycle/fuel-additives/pro-fst/

That equates to somewhere round 150ml per tank, or 100ml if you fill with 10lts of fuel and there's already some in there, round figures for convenience

 

3 hours ago, Scootabout said:

I imagine once the OP has investigated all these suggestions he'll get to the bottom of it. Out of curiosity, though, does the NC's ECU have a 'limp home mode', like some cars?  

There will certainly be default maps which will be used in the event of sensor failure etc. Whether there is a true "limp home" function as such, like many cars have, I really don't know. Without drive-by-wire throttle the potential is limited, if a certain amount of air is going in it needs an equivalent amount of fuel, it will only run within a fairly limited range of A/F ratios. I suppose it could potentially have reduced rev limiter under certain circumstances but I rather suspect not. The principle behind limp-home modes in cars is really to protect the emission control systems, and therefore avoid a high polluting vehicle in the fleet.

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motorbykcourier

Fuel pump??

I've had some dodgy fuel in the past and that clogged filter.

Managed to 'flush' system out to keep going - but it's still there and gives problems at times.

Bought a secondhand pump and just waiting on the 'inspiration' to change it - it seems quite an involved job to take tank out etc etc

 

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MikeBike

In the service manual there is a fuel flow test to be done by removing delivery pipe to measure the amount of fuel delivered in 10s to see if the fuel pump or filter are problematic.

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Graham NZ

And how to access the delivery pipe?

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SteveThackery

We shouldn't ignore what the mechanic said.  If it is dropping to one cylinder, it would produce symptoms very much like you've described, and that's maybe what the mechanic heard when he said it was "missing".

 

To be honest I'm not really comfortable with "try everything we've suggested" until it starts working again.  Every one of those suggestions could, indeed, be the cause.  But it's not always easy to check them.

 

If it were me I'd be taking a more organised, diagnostics approach.  Have you got one of those non-contact infrared thermometer things?  

 

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I would ride the bike until the fault condition arises, allow it to persist for 20 - 30 seconds, and then measure the temperature of the two downpipes as they exit the engine.  You'll need to stop quickly so they don't cool off too much.  If there is a significant difference in temperature then you'll know one of the cylinders is dropping off.  The coolest one will be the faulty one.  That will help you home in on possibly culprits.  If the fault is due to it running on one cylinder, you can discount all the causes common to both cylinders, such as airbox, fuel pump, etc.

 

Assuming you have a cylinder misfiring or not running, there is a slightly questionable, but effective, way of finding out whether it's a fuelling or ignition problem.

 

Warm it up and drive it for half a mile or so when the fault is happening, giving it a reasonable amount of throttle, then stop and have a look at the exhaust system.  If the problem is lack of fuel to the cylinder, nothing untoward will be apparent.  If the problem is lack of spark, the catalytic converter and silencer box will be extremely hot - probably making lots of rapid clicking noises and possibly smoking.  This is because all the fuel injected into the non-running cylinder will be burnt in the catalytic converter instead. 

 

With that information you can home in on either the fuel injector and its connector; or on the spark plug, HT lead and coil for the inoperative cylinder.

 

The above paragraphs (starting at "I would ride...") are an exact description of the approach I used on my Versys.  The fault on mine was a failed spark plug.

 

ON THE OTHER HAND... if you are sure both cylinders are behaving themselves equally (similar exhaust temperatures) then you can discount all the cylinder-specific stuff and look only at the common stuff.

 

Bearing in mind this has come on reasonably suddenly, I would venture to suggest this can't be anything like the air filter, dirty air box, etc.  A fault common to both cylinders that has come on reasonably suddenly is  more likely to be the fuel pump, or possibly a loss of electrical power (although I don't think that's it).  I'd be tempted to look at how feasible it would be to jury rig a pressure gauge which you can glance at when riding.  I don't think the NC has a fuel rail pressure sensor, so a faulty pump wouldn't generate a fault code.

You can also tape a multimeter to the fuel tank and watch the voltage as you ride along.  I've done that, too.

 

In summary, I recommend a logical, sequential, diagnostic approach rather than just trying everything and hoping you eventually find the cause.

 

Edited by SteveThackery
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sad vampire

The last bike I had that lost power in similar circumstance it was the coil, one before that was a plug cap getting hot, before that it was a plug lead. One before that was when the fuel ran out & I had to turn the fuel tap onto reserve & off it went again.

 

So, fuel supply or high tension electrics is my guess.

 

When plug caps & coils start to go they run fine cold & fail when they get warmer.

 

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