Idling probs and bike that keeps going with no key!

[monkeyking118]

Started up my bike this afternoon (can't ride yet so i'm just testing stuff out) and the engine will not idle without the throttle open.

idles fine when in choke or half choke at 1.4k, but refuses point blank to idle with no choke. it starts fine as long as the revs hit above 2k, any less and it just dies, whats gonig on, and isn't this a problem when i do actually ride my bike?

now the second part of the prob...
when in choke or half choke, the bike continues to idle AFTER the ignition has been turned off... i can even take the key clean out and it sits there happily ticking over! (obviously i do not know if this happens without the choke, because it won't idle anyway!)
I'm very confused about this!
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Baimo RSR125(sold), Suzuki En-125 '06 (sold), Honda VFR400 NC-30 '92(sadly stolen), Kawasaki ZX6R Ninja '96 (sadly stolen), Kawasaki GPZ500s '93 (sold), KTM rc390 '16 (f***ing stolen)

[stinkwheel]

Check your sparkplug. In some cases there can be a buildup of carbon on it which causes the engine to 'run-on' after switching off. More likely there is a fault on the ignition switch or the connections to it.

If you aren't riding it, I have my doubts if it will be getting warmed up enough to idle properly.
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“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[monkeyking118]

cheers, i'll leave it idling on choke for a bit to warm up and see where that gets me.

as for the ignition, spark plug has been cleaned so i guess i'd better check the wiring!

thanks, i'll post a reply as to whether any of this helped once i've had another chance to look at it tomorrow!
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Baimo RSR125(sold), Suzuki En-125 '06 (sold), Honda VFR400 NC-30 '92(sadly stolen), Kawasaki ZX6R Ninja '96 (sadly stolen), Kawasaki GPZ500s '93 (sold), KTM rc390 '16 (f***ing stolen)

[stinkwheel]

Just so you know. The usual case is that the ignition switch MAKES a connection between a wire coming from the ignition coil and earth when you switch it to 'OFF'. Earths the spark, kills the engine.
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[www.125power.com]

Cleaning the thread of the plug and the thread on the cylinder block may help it earth better.....
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[monkeyking118]

Just updating...

idling prob sorted, used the adjustment screw on the carb... now idles without choke at a nice 1.4k

ignition still a prob though, when turned off all the lights go out as expected but the engine still runs. going to get someone to check the wiring as i'm not confident enough to do this myself!

Cheers for your help people, much appreciated
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Baimo RSR125(sold), Suzuki En-125 '06 (sold), Honda VFR400 NC-30 '92(sadly stolen), Kawasaki ZX6R Ninja '96 (sadly stolen), Kawasaki GPZ500s '93 (sold), KTM rc390 '16 (f***ing stolen)

[sickpup]

[monkeyking118]

also forgot to mention:

The manual states that the engine stop switch should prevent the engine from starting, yet when this is set to "off" the engine can still be started.

anyone think these two electrical problems are linked?
____________________
Baimo RSR125(sold), Suzuki En-125 '06 (sold), Honda VFR400 NC-30 '92(sadly stolen), Kawasaki ZX6R Ninja '96 (sadly stolen), Kawasaki GPZ500s '93 (sold), KTM rc390 '16 (f***ing stolen)

[stinkwheel]

Almost certainly. Sounds like the wire running from the coil up to the ignition and stop switches is detached or broken. That or the earth connection from these switches is broken or rusty (assuming they share an earth connection).
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[meooo]

that, or its been hot-wired directly to the battery to by-pass the ignition and kill switch...........

[stinkwheel]

[meooo]

that would be true of a magneto type ignition, but if its not then a coil would need a constant 12v supply, which by putting it to earth would cause a short circuit.
the ignition swtch makes a 12/6v contact from battery to coil +ve, to switch off, it breaks that feed.

[sickpup]

[meooo]

now the second part of the prob...
when in choke or half choke, the bike continues to idle AFTER the ignition has been turned off... i can even take the key clean out and it sits there happily ticking over! (obviously i do not know if this happens without the choke, because it won't idle anyway!)
I'm very confused about this!




constant feed to coil...................
"would cause constant spark"

[Gazdaman]

Sorry, I believe a coil ignition does need a battery, a constant 12v circuit which is then broken by the points, where the phenomena that when a current is suddenly stopped inside a coil it induces a current in the other one. which in turn induces a current... and spark. Feel free to correct me if I'm wrong.

If it was magneto then it doesn't need a battery, although would need a fairly large capacitor.

It's far more likely there's a dodgy connection somewhere around your ignition barrel and maybe the right switchgear.

Gaz

[sickpup]

Not sure for certain if a battery is required but don't think it is. Vespa's with no battery have coils, at least the later ones do and CG125's with knacked batteries will run although badly.

My point was that coils are not constantly powered, connect up a multimeter to the low tension side and this will be proven.

As it is Stinkwheel is right about what the problem is but I'm not going to explain it and I kinda hope he doesn't either.

<edit>sorry confused there, magneto's have coils of course. 17 years since I worked on one<edit>

[meooo]

thank you, you are correct in your understanding of an ignition circuit operation.
I agree, the fault is probably a worn key/ignition barrel

[meooo]

for a coil to fire without a battery it has to be flywheel induced ignition...ie magneto system.......to stop these engines the coil must be earthed.

[stinkwheel]

I'll put it another way. You can start my CDI ignition Honda H100 with no battery in the bike. When I got it it had the ignition switch wired up wrong and had had a seperate button fitted to to earth the spark and kill the engine.

Many (most?) smaller capacity bikes have a totally seperate coil on the stator for the ignition which generates power all the time the engine is turning.
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[meooo]

yes, a magneto ign system.
& I understand how yours was by-passed stinkwheel, in that situation the only way to stop it would be to earth the LT side of the coil.

[Gazdaman]

Exactly, if this bike has a magneto ignition, then I would suspect it's a bad earth via the kill switch, and therefore not grounding the spark.

Whereas turning the ignition off just cuts the battery, which isn't needed.

And I guess it would normally cut the engine via the same earth as the kill switch. This is all mainly guesswork btw, but I would assume some kind of bad earth/corroded connector.

Gaz

[tribal_tiger]

Some people know nothing!!!

This is a dodgy earth connection. I told this to the guy i sold it to, and I thought I'd mentioned it to Monkey as well!

As for the idle problem. Once it warmed up properly it's fine. I know it's OK now you've adjusted it, but I think you'll find that when you are riding it, it will now idle a bit high. I found if the bike was sitting and you were waiting for it to warm up it took ages. I'd wait a minute or two then ride it gently. After a mile or even less it would be warmed up, and the revs would be fine!

Honestly, I'm away for the board for a while and look at you!!!
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All of it.

[monkeyking118]

cheers once again tribal!

you may have mentioned it, but my memory is preety bad, so i probably forgot!

should be riding regularly after sunday so i'll sort the idle for good after that.

so there we go problem solved! thanks everyone!
____________________
Baimo RSR125(sold), Suzuki En-125 '06 (sold), Honda VFR400 NC-30 '92(sadly stolen), Kawasaki ZX6R Ninja '96 (sadly stolen), Kawasaki GPZ500s '93 (sold), KTM rc390 '16 (f***ing stolen)