my first serious breakdown, engine died at speed!

[suzbug]

Hi guys.
ive just got back from a nightmare of a ride.. well, part bike ride, part transit van ride...
Thought it would be a nice day for a trip to whitby on the nc24..
i was doing the speed limit (plus a bit..) on the a64 dual carriage way when the bike just died!!
literally, the engine stopped and the tacho needle dropped to zero. i managed to get accros to the hard shoulder from the outside lane safely and pull up.
When the engine died i was in 6th gear, not giving it any beans, just enjoying the ride at about 80, and the engine lost spark. there wasnt a splutter, nor a missfire.
there is definatly fuel in the tank as id just filled up to brim 28 miles previously.
Before this, the bike was running lovely

when safely at the roadside i tried to start, the engine would turn over (nice and quick) but nothing.. not a splutter nor a cough..
i rolled a cig and pondered for a bit and tried it again.
This time it fired up and ran for about 5 seconds and died completely.
any further attempts was the same - just turning and cranking but with nothing else.
I pushed it up the road to the little chef and had a breakfast
came out and tried starting it..
turned the engine over and it fired, then 5 seconds later died again, with further starting attempts resulting in not a splutter.. -(it almost as if the engine kill switch is off but it isnt)


long story short, i dont have breakdown cover (stupid stupid stupid!!!) so had to call on a friend and van (Thanks Alan!)

So..
im home, the bike is home. but cant start it and looking for suggestions.
the vac pipe to the fuel tap was replaced and is clear pvc, this isnt kinked nor collapsed, and does not have fuel in it.
When cranking the engine the tacho needle apears dead, as in, it doesnt flutter as the engine is cranking.
The battery is good, all lights work and are bright. Engine cranks well.
Its just puzzling me that if left for a while it will fire, it will rev, but dies after 5 seconds...

Any help would be appreciated.. If i had hair i would be pulling it out!

Thanks in advance for any suggestions

[mattjc]

Had a similar issue with my wife's bike, turned out to be a bad earth connection from the battery. was a weird one because if I sat on it it'd be fine, I must have made the connection possible, if the wife sat on it nothing. but I am a fatty!

Got to be worth a look it's an easy check. (on a 30 anyway)

Good luck

Matt

[Mr_Fen]

I had a similar problem on mine, it was solved by replacing the fuel breather hose from the tank selector switch to the back right carb. The hose was supplied by Rick Oliver as he advised it, I thought that it might need a new fuel tap but his diagnosis of the problem was correct.

[amaechizzle]

Had a similar issue with my wife's bike, turned out to be a bad earth connection from the battery. was a weird one because if I sat on it it'd be fine, I must have made the connection possible, if the wife sat on it nothing. but I am a fatty!

Got to be worth a look it's an easy check. (on a 30 anyway)

Good luck

Matt

For your bike to die instantly, it would definately be electrical.
Check your earth's and fuses.

If it was a breather or something along those lines, the bike would splutter and feel as if running out of fuel.

[Neosophist]

Test the electrical system first...

Failing errors there

This sounds like a vaccumn hose / breather hose culprit too, espically at speed. Thevaccumn pipe collapses in on itself and starves engine of fuel.

[amorti]

I would be looking for a fault in the main earth. I had similar symptoms in my CB-1, this was the cause:

[Neosophist]

Ok I have had time to re-read your post now im home from work.

Tacho not registering anything isnt going to be related to vaccumn pipe.

Have you took any of the plugs out yet and checked for spark? Could be kill switch related.

The NC24 has a couple of earth points.

one is on the front two coils, if this is loose though your temperature gauge would read full hot.

Since its cranking over this is odd without seeing it.

Firstly id charge the battery up full and make sure its fully charged. Try starting the bike with choke and no throttle and see what you get.

If it refuses to start remove a sparkplug and make sure it is earthed and check for spark. Report back and we can go from there.

No spark + Fully charged battery points to electrical issues somewhere.

Spark indicates somethign else

[suzbug]

hi guys.
thanks for your replies

i had chance to look yesterday.
again, i tried starting it, cranked it over (tacho needle fluttering) and it spluttered a bit then nothing. Tacho needle still, no signs of life - just cranking..

I removed the tank. I checked all the connectors, wd40 them and plug in and out several times each to clean the contacts a bit.
I used my multimeter and found each coil had a good earth (<0.1 ohm)
When ignition on, coil also had 12v to other wires.
I didnt have a spark plug socket handy so didnt manage to take out the plugs to crank and test for spark..

I opened the wiring loom and traced all cable through. re-insulated afterwards as no sings of anything worrying.

I have tested the kill switch and that works fine. When i crank engine and tacho needle flutters, when i kill with switch it doesnt, but starts again when switched to 'run'

put the bike back together and still the same.
Had the battery charging and jumped from my old fiesta so it definatley had enough oomph. (turned over nice and quick!)

I did notice a sensor type item which screws / attaches to the block under the carbs. If i remember correctly it was in the 'V'
is this a crank position sensor?? it has two wires coming from it up to the connector plug bolck. It is inulsated with heat resistant shrowd.. i have a funny feeling about that wire...
Also, the ecu (?) is sealed so i cant look inside, but the plastic of the ecu box looks to have been plastic welded at some point, dont know if that from manufacture or from modification..

so, plenty of good fuel, good battery, cranks well, sometimes tach needle flutters, other times its dead, will fire up but dies after 5 seconds and wont fire again for an hour.. 12v to coils.. good earth to coils..

im thinkin ecu?? or carnk postion sensor?? but thats just a stab in the dark...

Any ideas or suggestions?? its really odd.. if it was ecu, why would it attempt to fire? surely it would just be dead??
i was hoping for a bad engine earth, that when runs for 5 seconds gets too hot and resistance goes up causing engine to die and has too high a resistance to run unitl it cools down, which it will then allow to fire up and so on.. but that doesnt seem to be the case...

HELP... Pleeeease..

[iDemonix]

Weird about the tacho, but aside from that I had a similar problem.

Was doing about 40mph and tootling along when the bike quite suddenly cut out. Rolled to a stop as it was red lights ahead anyway, tried to start up again, started then just as I gave it a bit of throttle it died. Cranked again and got about 3 seconds of running but the slightest touch of the throttle killed it - after this it wouldn't start at all.

Pushed it to my dads warehouse which wasn't too far away and was loaded with tools, took everything apart and the vacuum pipe from the tank to the rear right carb was bent slightly, enough to restrict flow. I took it off and blew through it to ensure it wasn't blocked, then I took off the tank breather and blew an air gun through the petrol line (and petrol came out the breather like a whale, should of took the filler cap off...). Reassembled and recharged and it ran fine.

Might be a completely different problem, but worth checking all your fuel lines, breather lines and vacuum pipes for any slight kink or block?

[suzbug]

i was looking on ebay last night and saw ignition pick ups and ecu for sale...

the thing is, the ecu looks different to the one in my bike.. has anybody got pics of their ecu's from an nc24 to confirm i have the right one??

Where should i be looking for ignition pick ups?? I didnt see any on my engine??

a friend is lending me his timing strobe so i can test is the plugs are getting ht to them when i crank it over..
ive got a feeling its spark and electrical related..

does anybody know how the coils 'know' when to spark if this engine doesnt have pick ups??
im not familiar with how this works, theres no distrubutor, so it must be getting information as to where the engine is and which to fire..

just as the weather turns nice the bike dies... arrrrrrrrrrghh!! ive been comuting most of the winter on it, freezing my conkers off, and just as the weather turns nice i cant go for a pleasure ride..