Sparks only from right hand side coil GK73A

[jamesgoodfella]

Hi,

Bought myself a gk73a to use as a road legal track bike and I was told by the pervious owner that there was no spark on cylinder 3, bought new coils from a gsf650.
Plugged them in and I only get a spark from the right had side of the coils and they only spark when you toggle the side stand switch. Any ideas?

[SevenThreeSeven]

could be as simple as a bad HT lead (or leads) from one coil. The bike is pretty old so treating it to new HT leads would probably be a good thing and not that expensive either.

[jamesgoodfella]

I'm using coils from 2007 GSF650 and using the leads from that.
I've read online it could be something to do with the CDI or side stand switch. The switch was previously taped up by the previous owner but now it only gives a spark of I toggle the switch no idea what it could be, I'm used to messing with my CB350 K2

[Variablevalves suck]

Treat yourself to the service manual on the front of the site and then have a good look at the wiring diagram.
There must be a short of some kind as the side stand switch should only switch off the ignition if the bike is put into gear with the stand down, the previous owner had shorted it so the stand was effectively always up.

It's not too complicated and works by simply grounding the signal out so the fact it works / stops when you wobble it shows the fault is that end.

[jamesgoodfella]

I'll go back and check the wiring, hopefully this will solve the issue of one of my coils not working at all

[minkathecat]

YOU SAY NEW COILS ARE THEY ........new
TEST THAT COIL WITH A VOLT METER BOTH PRIMARY AND SECONDARY CIRCUITS
LOOK ON UTUBE HOW TO DO THIS
(DO NOT DO NOT TAKE THE CIRCIT TESTER OFF WHEN READING AS SOMETIMES THESE COILS DONT SHOW BAD COIL STREIGHT AWAY SHOULD SEE THINK IT 3.5 IF IT STARTS TO DROP COIL IS CREAM CRAKERED THROW IN BIN.
this will tell you that that coils circuits are correct.

next as variable valves says check the side stand switch and wiring with your voltimeter for continuity.
the line from the side stand goes to your cdi unit think its green check the continuity all the way up to this.
then check when stand down is on and off when up.
depend wether you want to do away with stand as when you start off and dont put it of it wont tell the cdi to stop the engine (do you wana be safe or not especialy if you got a disk lock on?) just saying.
i suspect it could be a little bit of both here.
oh and you could check them risistors in the plug caps if you take them off when checking your coils.
regards john

[dobbslc]

Have you tried swapping the coils over to check them? If the fault moves with the coil, it's the coil that's fubar, if it stays in the same place it could be the cdi that's knackered.

[jamesgoodfella]

Have you tried swapping the coils over to check them? If the fault moves with the coil, it's the coil that's fubar, if it stays in the same place it could be the cdi that's knackered.

Swapped the coils and it is not the coils that are at fault, was the first thing I checked. If it is the CDI i'm looking at £100 for a replacement which I seriously don't want to shell out for as I only paid £350 for my gk73a to use on track. Is there any alternative to buying a replacement CDI possibly from another bike or is there a fix I can do. Call me stingy but I've got a apprentice wage and I'd rather spend the money on my other bikes when this was meant to be a cheapo track bike

[Variablevalves suck]

Have a good check of the wiring to that side before getting drastic
BuT if its 100% the cdi they can be fixed so long as you are confident using a soldering iron

Common cause is the 5 capacitors and the two other things that I forget as I write but if you go over to the banditalley site and search the 400 section for CDI repairs there have been a few well documented posts with everything needed to fix the problem.

[jamesgoodfella]

Yes that's the site I stumbled on earlier right after I replied today so I've popped home to pick up my CDI and going to have a look it with one of the electrical tutors back at college.

I'll have to search for the wiring diagram tonight then, from a basically inspection the wiring all seems the same but will also go over with WD40 on all the connections