anyone had this situation before?

bugsy46 · Village Idiot Joined: 16 Mar 2004 Karma :

Was working on a Thundercat today, and noticed the bike wouldnt spark, upon looking it seemed the kickstand had to be placed up, with the bike in neutral for it to fire OR the clutch had to be pulled in. Now obviously the clutch switch AND the sidestand switch are working, what seems to be logical is that the CDI thinks the bike is in gear, even though there is a neutral light which would suggest the neutral switch is working fine too. I have no experience of yamaha wiring looms and was wondering if anyone else has had the same problem. My feeling is that there is a problem within the loom. Any suggestions will be taken on board, thanks
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Whosthedaddy · Super Spammer Joined: 11 Dec 2005 Karma :

Seems normal?

The ZXR had to have the clutch in to start (the 7R sometimes the same) and side stand switches are anyones guess Laughing

The FZR wouldn't start in gear despite the clutch pulled in.
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bugsy46 · Village Idiot Joined: 16 Mar 2004 Karma :

LeeR · World Chat Champion Joined: 12 Dec 2006 Karma :

Yup my Suzuki's have all needed the clutch in, whether in gear or not, and I'm not too sure but side-stand up as it has a switch, so I just flick it up anyway from habit.
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bugsy46 · Village Idiot Joined: 16 Mar 2004 Karma :

LeeR · World Chat Champion Joined: 12 Dec 2006 Karma :

iooi · Super Spammer Joined: 14 Jan 2007 Karma :

My divvy wont start with the side stand down, even when in netural...
Now i know the clutch switch works coz if its in gear it will only start with clutch in. Side stand switch works coz if you put it down it switches the engine off.....

Really annoying problem. But i can't be fussed to find the problem.
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bugsy46 · Village Idiot Joined: 16 Mar 2004 Karma :

Lol. No mate I havnt had it from new. Its on my ramp at work! The bike isnt in for this problem, its had motad downpipes and a major service. However Im interested as to what the problem is even though it isnt our problem.

bugsy46 · Village Idiot Joined: 16 Mar 2004 Karma :

No worries, without looking at a wiring diagram, there should be a wire that collects all three switches which routes to the CDI, might be a problem somewhere along that feed
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Laura - "And where did looks come into this and bugsy leave steven alone. You are not gods gift to women you may think you are but you're not."
Keith - "All the best"

stinkwheel · Bovine Proctologist Joined: 12 Jul 2004 Karma :

Well, when I've looked closely at these kind of things before, here's what usually happens.

Basically there is a relay in the 'black box' between the starter switch and the solenoid. Pressing the button puts power to this relay. The switching side of the relay is not connected directly to earth. It usually has three options, it can either earth through the clutch switch being pulled in, the sidestand switch being up or the neutral switch being in neutral.

In the case of a bike where you need all three to work the starter (eg, you need the stand up, clutch in and being in neutral to work the starter), the switches are connected in series with the eventual earth being via the neutral switch.

On most bikes I've ridden (and certainly on my Dads Yamaha Dragstar), the neutral switch and the clutch switch are in paralell meaning the starter can be operated all the time if in neutral and only with the clutch pulled in if in gear, the sidestand switch having nothing to do with the starter lockout.

The sidestand switch is usually just connected to the engine cutout system which prevents you riding off with the stand down. This is usually via a wire coming from the CDI that needs to be earthed for the CDI to throw a spark. In this case, it is usual to have the sidestand switch and the neutral switch in paralell. The CDI earths through the neutral switch when in neutral and through the sidestand switch in the up position when in gear.

In summary. I surmise your problem is a bad connection between the starter relay in the junction box and the neutral switch. Follow the wiring diagram back from the neutral switch. There should be a wire leading up to the switching side of the starter relay. I suspect this is broken or detached.

Simplified diagram of 'universal' starter lockout system attached.

EDIT: You will notice that these two systems 'overlap' at the neutral switch. For this reason there is often also a diode in each of the wires leading out to the three switches in question (just after the starter relay but still inside the junction box). Incidentally, the relay is usually a very small one soldered to a PCB because it isn't handling a lot of current, it's simply being used as a logic gate.
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bugsy46 · Village Idiot Joined: 16 Mar 2004 Karma :

Hmm interesting read stinkwheel! I hope one day I can be as fluent as yourself with auto electrics! Funnily enough in this case with the thundercat. It allows the starter motor to run, but it doesnt produce a spark, so, would I be right in saying that it would be more down to a connection disabling a spark? ie CDI?!?!

I pictured the CDI thinking "THIS BIKE IS IN GEAR!!" when actually its in neutral!!
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Laura - "And where did looks come into this and bugsy leave steven alone. You are not gods gift to women you may think you are but you're not."
Keith - "All the best"

stinkwheel · Bovine Proctologist Joined: 12 Jul 2004 Karma :

druidsam · Crazy Courier Joined: 01 Sep 2007 Karma :

my 98 thundercat will start with the side stand down and without holding the clutch lever in, but it has to be in neutral,if the engine is running and the stand is down the engine cuts out immediately when you click into first gear.dont know if that will be of any help to you,but thats how mine works Very Happy

............................Sam
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bugsy46 · Village Idiot Joined: 16 Mar 2004 Karma :

Thanks stinkwheel! Perfect explanation!!! Big credit to you for that!! Thumbs Up

____________________
Laura - "And where did looks come into this and bugsy leave steven alone. You are not gods gift to women you may think you are but you're not."
Keith - "All the best"