NC24 Big help needed Please!!!!!

[Lucky Tampon]

Hi all, got an NC24 not long ago and i'm now having some issues with it.

One cylinder (no.4) keeps dropping out intermittently, and very occasionally the other front one (only happened once so far). At first i thought the spark plugs were knackered and that was what's causing it so i replaced them but i'm still getting the problem, which lead me to believe it was the front coil but after a bit of reading about on here it would seem it could quite possibly be that the carbs need balancing and setting, though i've not ruled out the coil yet.

I've seen a few people on the interwebz make their own balancers but is it really worth doing and do they produce accurate enough results? I'm not in a position to be able to buy a proper gauge at the moment. Or if anyone is in the Lancashire area and would be willing to lend me a carbtune or similiar for the day i would be more than happy to chuck a few quid your way

Also i'm looking to do the valve clearances, had a read of the guide for the 30 but i'm sure i read that it's adjustable on the 24 and a different setup? Would consult a Haynes manual but the never did one for the 24

Would be good if someone could point me in the right direction.

Cheers
Lewis

[speedy231278]

Having looked at the home-made balancers they seem to work very well, and if fact are probably more sensitive than something like a Carbtune, however do you really want to go through the hassle of making one yourself? If you are successful it appears that you get really good results, but if I tried I'd probably end up sucking the water into the engine! lol

The method is nice and simple. Connect two sealed bottles of water together with a tube. Connect a tube from each bottle to the two carbs you wish to sync. I guess if you want to do all four, you have two pairs of bottles, and link them together as well as to the other carbs. I think I'd just do one pair, do the other pair, then replace the inlet caps on one each front and rear and balance using the other two....

Unlike a 'proper' vacuum gauge like a Carbtune, you are not measuring the vacuum level. You are simply comparing the level of each carb. The actual vacuum level, so I understand, is not important as it varies with engine speed. You simply want to get all the cylinders drawing the same vacuum at a given engine speed.

The principal is simplicity itself. Ignore the comparative water levels in each bottle as they don't matter. What matters is fluid transfer. if the carbs are not balanced, one will have a higher level of vacuum than the other. This means that as the bottles are sealed from the atmosphere, but joined to one another, the carb with the higher vacuum level with cause water to be sucked from the bottle connected to the other cylinder. So, regardless of how high or low the water is in each bottle, if it's not flowing from one to the other, it means both cylinders are drawing the same vacuum, therefore the carbs are in balance.

I like cheap. I also like decent tools, and I'm crap at making things like this. Earlier this week I bought a Carbtune...

As for the valves on 24, I'm sure there's a guide kicking about, they have some locknut arrangement or something like that. Sounds a bit complicated to me, but is does mean you presumably won't need replacement shims. I once got stung by a place who changed 11 of mine, and despite the fact you can guarantee they have their own 'shim bucket', I got charged for 11 new ones at about £6 plus VAT each, and that was almost 10 years ago!

[speedy231278]

Valves - take a look at Page 14 of the valve clearance guide that's stickied at the top of the forum...

viewtopic.php?f=24&t=1943&start=130

[Neosophist]

Valves - take a look at Page 14 of the valve clearance guide that's stickied at the top of the forum...

viewtopic.php?f=24&t=1943&start=130

Yes no shims for the NC24.

The NC24 also has 4 coils, 1 per cylinder.. could be a knackered coil on that cylinder, you can swap the coils over and see if the problem is reversed.

Balancing should only give a smoother idle so I doubt it is that. When does the cylinder drop out?

Its either carb or plug/coil related, shouldnt take long to fix

[Lucky Tampon]

Thanks for the replies. Nice one on finding the valve clearance guide for the nc24 speedy :) and also on your info on carb balancing.

Will try swapping coils over when it stops raining and see what happens. It drops out mainly in the lower revs (under 8-9k) and is completely random as to when it happens, sometimes it will drop out altogether though most the time it's on and off like it's misfiring and jerks when trying to accelerate because of it, i've tried running with lights on and off etc to see if it makes any difference which it doesn't. Generally speaking when it drops out altogether if i drop down a gear and put it back up into the high revs it will kick back in again.

Other times i can ride it though and will not have a single problem with it, it's pretty much a game of luck as to wether it will work properly or not lol. As mentioned i replaced the plugs all round last week so i'm not running any duff plugs, i'll admit also i've not cleaned the carbs out as of yet due to the fact that if any of the inlet manifolds split when i'm doing it i will be well and truly fucked as it's my only method of transport and i'm a bit too skint to be replacing anything at the moment, having said that i may do it today as i shouldn't (fingers crossed) be needing any transport until tuesday which would give me time to arrange funds for any replacement parts needed.

[Neosophist]

Thanks for the replies. Nice one on finding the valve clearance guide for the nc24 speedy :) and also on your info on carb balancing.

Will try swapping coils over when it stops raining and see what happens. It drops out mainly in the lower revs (under 8-9k) and is completely random as to when it happens, sometimes it will drop out altogether though most the time it's on and off like it's misfiring and jerks when trying to accelerate because of it, i've tried running with lights on and off etc to see if it makes any difference which it doesn't. Generally speaking when it drops out altogether if i drop down a gear and put it back up into the high revs it will kick back in again.

Other times i can ride it though and will not have a single problem with it, it's pretty much a game of luck as to wether it will work properly or not lol. As mentioned i replaced the plugs all round last week so i'm not running any duff plugs, i'll admit also i've not cleaned the carbs out as of yet due to the fact that if any of the inlet manifolds split when i'm doing it i will be well and truly fucked as it's my only method of transport and i'm a bit too skint to be replacing anything at the moment, having said that i may do it today as i shouldn't (fingers crossed) be needing any transport until tuesday which would give me time to arrange funds for any replacement parts needed.

The inlet rubbers will probably be well and truly knackered by now anyway (hard)

There about 5 quid each from david silvers (youll need 4)

Re-fitting the carbs can be tricky with hard old rubbers.

Interesting.

Balancing will only improve the idle tickover.. since your problem is at high revs and only intermittent that narrows it down a bit.

If it was a blocked up carb jet it would be a constant thing.

Without looking at it sounds like either an intermittent electrical issue manifesting itself as a misfire, a faulty coil breaking down (not sure why dropping down gears would fix it...)

Have you considered fuel flow?

The fuel tap is vaccum operated, theres a spigot on the outside of cylinder 1 (rear left, partially blocked by the frame) the pipe that runs from there to the fuel tap can split and become crap with age.

Particullary at high rpm the hose can collapse in on itself and shut off the fuel until you back off, which will cause a missfire due to the carb running out of fuel.

This is usually when giving it some beans but its always worth chcking out the hose.. give it a pull where it joins the spigot or tap and see if it splits or is brittle. New ones are cheap.

[Lucky Tampon]

Yeah i figured as much with the inlet rubbers, may just have to bite the bullet and order some new ones.

I was almost certain it was the coils at first but a bit of reading about lead me to believe otherwise, my theory on dropping down a gear is that at higher revs it could be generating more electric in turn providing the faulty coil with more power to run properly.... but that's a pure guess as i'm useless with electrics haha.

Tbh i don't think it is that pipe mate, i have however checked it and i can't see any cracks or splits anywhere. Though it does feel a bit soft :/ running at high RPM i.e redlining through the gears it pretty much runs sweet as a nut, but it's when trying to cruise normally that the problem occurs.....

I'll see if i can get a video of it tomorrow if that will help?

[speedy231278]

If you don't want to rip the carbs to bits, perhaps getting some of that carb cleaner you put in the petrol might possibly help? Not used it myself, but according to my old mechanic it was the next best thing, especially if you put plenty of it in a fairly empty tank. Dunno what going for a ride with it in would be like, maybe having a turbo.... lol

[Lucky Tampon]

Don't think that will make any difference tbh mate lol.

As said previously it seems to be an electrical fault, at least i hope anyway! Doesn't help that half the wiring loom is bodged up to fuck

[Lucky Tampon]

Ok... New problem lol. Just went out to help my mate out who broke down on his RS125 and on the ride back, after covering about 10 miles in the pissing rain the bike cut out then came back to life again and kept doing this along with some almighty backfires then eventually would cut out altogether at which point i would have to bump start it.

It kept going on like this for about 4-5 miles until eventually it died altogether and wouldn't start so i ended up pushing it home (luckily i was only about a mile from home).

So my question is..... WTF?!!! Lol, i really need help with this guys, i've got 2 job interviews next week that i need my bike for

I'm almost convinced the problem is electrical, following on from my previous problems and i'm on the verge of replacing the loom/CDI/coils/reg-rec. But before i do this i would appreciate it greatly if someone could shed light on the situation before i go chucking money at it.

Many thanks
Lewis