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CX-GL Honda MCC

I Used To Have One Of Those

Peter

Occasional Starting Problem

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During my last European ride around with PeteG I had a problem starting the bike after a brief stop.

 

Engine warm, fresh fuel and a good battery and when turned off, running like a clock and doing 55 ish to the gallon. Cold starting - instant.

 

Occasionally, 3 times in about 3 weeks, after having been stopped for a few minutes, maybe 5 to 15, the engine refuses to start. Turns over fine, just refuses to fire up. After a LOT of cranking and even more swearing suddenly she starts and runs perfectly as if nothing was wrong.

 

I have eliminated the kill switch by disconnecting it. The Ignitech is getting power and the carbs have fuel. I have an inline filter but that is clean. Plugs are Iridium, clean and correctly gapped. Wiring to and from the Ignitech is clean and connections are good.

 

I stress that the bike runs like a dream when running, smooth with all the pull I would expect. Top speed doesn't seem to be limited in any way.

 

Any ideas?

 

My only thought is an occasion fault in the Ignitech but difficult to prove as the problem is unpredictable. I will, until a solution is found, be carrying a spare Ignitech.

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Chris, I've pretty much discounted the ignition switch. The Ignitech is getting power and I fitted a link In the kill switch circuit so I could easily disconnect the ignition switch/kill switch.

The bike starts and runs so well 95% of the time it's a devil to find what is going on. I'm going to make a spark tester today and carry that and a spare Ignitech with me ready for next time.

Normally I use one of the other bikes for running around locally but the CX will be my sole ride until I solve it. I don't want to be setting off on another Euro wander until I'm sure of the old girl.

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Peter, you know your onions but surely - if you've got the plugs resting on the head (not yours) earthed out, then you can tell the state of the sparks ie ignition? It's never going to delay or advance it - just no spark or weak spark? I would have thought that decides for you step 2 either further ignition work or carbs. One last question- does / did it only do it when abroad? Fuel differences regarding ethernol? Long shot I know but that happened to me on my Benelli.

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Marty, unfortunately every time it did it I wasn't ready for it and just had to get her going and, after I borrowed a spare plug from Pete, ofcourse it didn't do it. Next time I will be ready!

I don't believe fuel quality is an issue, even with the ethanol it never has before. I avoid the e10 whenever possible even to the extent of putting 98 octane in and paying though the nose. These old bikes aren't set up for high ethanol. If I'm pushed and have to use it I find she doesn't run well at all but she does run.

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My guess would be a slightly sticky fuel shut off valve or slightly high fuel level in the float chamber. If it is too high then the fuel could spill into the inlet tract giving an over rich mixture. If left for longer the fuel will have evaporated and not cause an issue but with only a short time it can't evaporate and effectively floods the engine.

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Just a possibility but when a hot engine is stopped there is a build up of heat due to no coolant being circulated and no cooling air passing through the radiator. This can cause the petrol in the inlet ports to vaporize and prevent the engine starting. Usual solutions are to give it a bit more time to cool or to open the throttle wide and gradually close it with the starter running. Sods law but you probably won't be able to recreate the conditions for test purposes.

This used to be a problem with the old side valve cars.

Colin

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Dusz/Samnav

Thanks for you thoughts. Food for thought but under either scenario I would expect a bit of a cough/sputter, perhaps running on one cylinder for a second and perhaps a puff of black smoke. Nothing like that occurs, she just eventually fires up as if nothing was wrong.

I have tried throttle open, closed and swinging between the two.

On one occasion we had only covered about two miles. She was barely warm so I'm inclined to dismiss vapour build up.

I just wish the darn thing would do it again now I'm ready for it!

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At last she did it when I was able to diagnosis the problem.

No spark, no start - simple really.

Voltage and earth good at Igntech, all connections look sound.

Ignitech substituted, no start.

Cdi reconnected, instant start. So pickups and all other associated bits are ok.

Next move will be to substitute the Ignitech wiring harness, I had a doubtful connection years ago on one of the plugs, I'd forgotten about it until I started poking about so I am hopeful the fault can be pinpointed. Back at it tomorrow.

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have had similar problems over the years! now whenever i reconnect multipin connectors i always make sure that non of the wires has pushed back in the block making a borderline connection. but poor hot starting can be a real bitch to sort out, have played extensively with big singles which when hot can reduce you to tears and or hernia! solution? fuel off full throttle and clear engine out. generally will restart as normal

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Well an hour or so poking around has yielded nothing positive really.

Old Ignitech harness removed and examined in some detail, no fault either mechanical or electrical found. No sign of loose or scorched wires and continuity good.

New harness fitted and she now starts as normal.

Just wish I could find an actual fault. So it's back to ride and see what happens.

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You have our sympathy Pete. The very worst sort of fault. I suppose the only up side is you have good reason to get on the bike and just ride till it / if it stops. You'll need a reasonable bag of tools of course.

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Difficulty hot starting was a problem with old BMW boxers that had an older heat sensitive coil (grey one i think) that when hot wouldnt start the bike, when cold fine !!

 

Eric.

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Well now what?

Having changed the harness I expected that all would be well today but she did it again!

Quick switch back to the Cdi and instant start, perhaps a little quicker than the Ignitech when it works (significant?).

Having substituted the Ignitech and found no improvement I put the old one back but I'm now thinking maybe I may have done something stupid like maybe knocking the kill switch off, wouldn't be the first time.

So tomorrow on with the new Ignitech and try again.

Good job I'm a patient man - ask my wife

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I found carrying a small hammer is enough of a threat that the bike starts all the time !!

 

On a serious note - is your battery in tip top shape ????

 

Eric.

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Eric. Good advice, I will look out my toffee hammer at once but will show her the escalating range at my disposal

On a more serious note, the battery is first rate, I have a Motobatt fitted and she spins over at a good rate.

As soon as I reconnect the Cdi she fires up.

I have checked the voltage at the Ignitech when cranking and it drops no more than I would expect, maybe a volt or so when she's warm. Cold starting is fine, I would expect a larger drop then but she always fires up no trouble.

I'm switching the Ignitech today and trying again. If it still fails then I will rewire the Ignitech supply and earth from scratch, maybe direct to the ignition switch.

Hope springs external

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A case for Sherlock Holmes this one.

"Once you eliminate the impossible, whatever remains, no matter how improbable, must be the truth."

Once again she failed to start after a run and a brief stand despite having replaces all things Ignitech related and even wired it, via a relay, direct to the battery.

Got her back home and started probing with the meter. All was as it should be until, in desperation, I tested the high speed and low speed coils, these provide the trigger pulse for the Ignitech. The resistance was high on all except one which was open circuit. As things cooled down the readings dropped back to more correct levels and the one open circuit began to read, albeit with higher than correct level.

It seems the Cdi is far more tolerant than the Ignitech, running well even with significantly incorrect resistance.

So it's an engine out, back cover off job as I don't really dare run her too far even on the Cdi.

I need to check the timing chain/tensioner blades anyway as I'm getting a bit of a rattle from that end and the oil pump chain chain needs retensioning/replacing possible as well.

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Well done Peter....get all the work done and I'll give you £200 for the bike including the spare ignitec.....now dont snap my hand off !!

 

Eric.

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Eric, that's an offer I almost can't refuse however if you add a zero to the end we may, only may, be able to start negotiating.

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Ok then you got me, £0200 - cant say fair than that !!

 

Eric.

 

Wrong end Eric

 

You know I seem to recall a very smutty school boy joke which ended "wrong end" but memory fails to provide the preamble

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