Back in UK after 3 months. Now bike won't start (round 2)

[Lord Percy]

Well, it was working when I left, and now it's not!

Engine turns over but possibly there's no spark. The plug caps are so deep that I can't just put them against the tank to test.

Thoughts? Gammy fuel? Water or rust in a bad area? Or maybe it just needs a load of turning and turning until it chugs into life?

Main point is that it worked 100% fine when I left and now it won't start. And I think it's not sparking.

Honda CMX 250. (Mechanically the same as a CB250, as far as I know)

[c_dug]

Is the battery fine?

I've found a decent bump start to be more effective at getting a stubborn bike to start than just cranking the starter motor until the battery is flat.
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[doggone]

I've found it's not unusual for mine to be reluctant if not used for more than a couple of weeks.
Last time I eventually went to dig out some easy start, but when I came back to it it started without it.
In other words, give it a prolonged starting session then an break then try again after 10 minutes or so before getting too hands on.

Jump leads would be good to be sure you have maximum crank speed.

[Lord Percy]

Update:

Definitely no spark. Pushed a bit of copper wire into the plug cap to connect with it properly and there's not even the slightest pop.

It's jump cabled to a car now so the engine is turning over absolutely fine.

Just no spark!

The kill switch is at the correct setting, kickstand light is off, it's in neutral, etc etc.



What could electrically go wrong if I haven't touched it? ......water in the cables?

[Lord Percy]

Update 2:

The engine actually has two spark plug jacks, and both plugs aren't working.

So I don't think it's a wiring issue. I think something may have jammed somewhere so the engine has been 'kill-switched' somehow.

No idea what to check though. Hopefully it's just gonna be a really obvious textbook human error. Although I do think I've checked everything.

[lihp]

do the test with a plug in it. Hold threads against frame.
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[Lord Percy]

[lihp]

Are all your other leads and plugs connected?

What bike and year is it?
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[P.addy]

Does it still turn over if you flick the killswitch to off?

If so, I'd initially be checking the contacts in there.

[Lord Percy]

It's a Honda CMX 250 2001. I think mechanically it's similar to the CB250.

With the killswitch set to off, it does still turn. But I think it's always been like that as I've had killswitch fails several times before.

Killswitch is still a good shout though. I'm gonna have it apart and check.

[Lord Percy]

Well that's the last time I take a kill switch apart . Some tiny ball bearing fell out of it and it was fiddly as anything! Checked the contacts and they seem fine. I've put it back together, minus the ball bearing because I can't even figure out what it was for and I lost it anyway...

Still no spark.

[Pie-Roe]

Where was the bike kept?

Have you tried taking off the ht leads and spraying some wd40 up them? When it snowed water used to get into my cb250 in the ht cap somehow. Also there was a block connector on the left hand side that would sporadically loosen itself off.
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[bikenut]

:D hi percy,

see what happens when you leave them all alone...........

no spark: does the cdi have a black/white wire coming from it as a single wire with bullet connection??????

if so, disconnect it. and now try for sparks, making sure that the plugs in the caps contact properly ( rather than hoping they do ) to earth!!!!!!!!

if it does spark now, then there is a fault in the ign kill circuit.....which will be in the main ign switch and/or the handle bar kill switch, the one you took apart.

the black/white wire is earthed to kill the ign usually.

some pics would help, you have a wiring diagram to study and prove the wiring and earth to kill ign etc etc.......

when you have sparks, the fuel would be next, as modern fuel goes "off" quickly and is bad for the system ( increased methanol content ).............drain tank and carbs and flush, some redex fuel system cleaner may help.......then onto fresh clean fuel.

any water /condensation in the tank or was bike stored in a very dry room??

service and charge the battery ( as it needs to whizz the engine over quickly to generate the energy for the cdi system, as your may be non battery dependant ) for a hot spark and good starting.

if it bursts into life, dont rev the bollocks off it and bend a valve, just leave ticking over ( with adequate cooling ) outside for a while.............then service the rest of the bike................pics pics pics........

does it have a kick starter??
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nuts about bikes

[Lord Percy]

Pyro, bikenut, top info, cheers!

I'll have a close look at all those things tomorrow. I've given up for today as jetlag has gotten the better of me - went to bed last night feeling shattered, then woke up at 3am and couldn't sleep again!

I'll let you know how I get on.

And nope no kickstart. Also the battery is a little flat from me turning the engine so much, but I'm jump starting it off a car now so it's back to full whack again so no issues there.

Definitely seems most likely that there's a 'kill' operation happening somewhere when it shouldn't be.

I'll check it all over tomorrow.



Oh and it was kept outside for the whole time, under a thick tarp. So moisture could be the cause.

[Suntan Sid]

Had, remarkably, similar issues with a bike of mine that hadn't been started for a while.
A new spark plug, inexplicably, fixed it, started straight away!
There was no reason a plug should have failed, there was no visible damage to it, but fail it did!
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[Vincent]

You'll need the little ball bearing for the switch .
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[Pie-Roe]

[bypass2]

did you spray wd40 in the kill switch maybe damp. what about a faulty side stand switch if one is fitted. you need the little ball bearing you lost

[Lord Percy]

[Aff]

[Lord Percy]

[Lord Percy]

Update: FIXED!

It was presumably something to do with the CDI but I have no idea what.

The black/white wire was actually a two-pinned thing, so when I pulled it out, another red wire had to come out too. Google Images tells me the red wire went to the alternator.

I turned the engine but still no luck. And then - heh this bits all a blur for some reason - I can't remember if I'd reconnected the CDI or not, but I decided I'd give the plug caps one last test, turned the engine, got a nice shock in my hand and it chugged into life with the remaining spark plug still in the engine.

And now it's all back together and works like a dream. Happy days.

I guess it was a poor connection somewhere around the CDI? Or by removing the black/white wire, I reset a capacitor or something and made everything hunky-dory?

Anyway. Win.

Now I just need to hope it survives the journey into town because..... I checked the fuses and kind of broke one of them and now it's precariously positioned so that a circuit is still made but it could bounce out of place at any moment......

Thanks all for the help, specially to bikenut as I think is was your CDI tip that led to it being solved.

[Boxing]

As for fuses, can pick them up from most shops on the cheap side.

Blew mine, picked a new fuse up for about a quid.

[bikenut]

i hope you have fixed the kill switch..............and serviced the rest of the bike and its brakes, as well as all electrical connections.........you know it makes sense..........

red and a black/white wire.............red from genny and b/w to earth to kill ign??

any other wires on cdi unit??
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nuts about bikes

[Vincent]

The switch and ball thing........if it's the type of switch I think, the ball does indeed locate on a dimple either side of the switch so that it locates correctly ........ and the switch probably feels vague without it and could move freely, but also, without the ball, the spring isn't long enough to push the slider against the contacts properly. 'Could cause problems further down the road. I might have an old switch I can canabalise if you want to put one back.
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