Common faults (GK76a Won't Start!)

lordcalv · Post by **lordcalv** » Sun Feb 01, 2009 3:28 pm

Does it only do it in the rain or is it completely intermittent?
The CDI on a 76a sits in a tray which has the potential to fill with water if any gets in under the pillion seat. I'm guessing that if the expansion tank was overfilled or has a leaky/no lid then it would catch a fair bit of coolant as well. Worth a shifty under the pillion seat.

Jaicen · Post by **Jaicen** » Sun Feb 22, 2009 9:42 pm

Ok, now that the snow has gone from my end, I've started using my Gixxer again. It's been running just fine for about a week, until last night. I drove it to work just fine, finished work and filled up with super unleaded and went for a drive (just 25k, too windy!). When I tried it today, it wouldn't start at all, this morning or evening.
So, i'm pretty pissed off with it for letting me down again, but i've resolved to fix it. So, can someone point me in the direction of a new CDI unit, and/or ignition coils. I'm pretty sure I can replace them myself, but that's probably as far as I can go right now, if only because I lack time.
The intermittent nature of the fault surely suggests it's an electrical fault?

Post by **Variablevalves suck** » Sun Feb 22, 2009 10:47 pm

Hi Jaicen,
Dont buy a new Cdi just yet, if the fault is intermittent i doudt it will be the Cdi as they are transisterized and so usually work or dont. Like Will said it could be water or an electrical fault or one in the same so you need to take a look around, is there someone you know with some basic mech knowledge that can help. You may just have a loose terminal or ht cap/lead or a worn wire touching the frame, im sure if it runs sweet some of the time then it will be something simple.
Chris

Jaicen · Post by **Jaicen** » Sun Feb 22, 2009 11:20 pm

That's pretty much what I thought with regards to the CDI, but I know that there are also some caps and stuff in there which can age, particularly if they're sinking some big currents. Unfortunately, my CDI seems to be potted and unrepairable so that's out of the window.
I've had a look for loose connections and things, and I can't see anything. There don't seem to be any loose wires either.
If I gave the impression i'm not mechanically minded, that might be a bit misleading. I've rebuilt my Lambretta a couple of times, and i'm pretty good with electronics (mostly audio though...

). The trouble I have is the lack of manual, so I feel i'm working blind a little bit!

The thing that makes me reluctant to buy another CDI, is that it's going to be secondhand, so what are the chances of it going wrong again?!

EDIT: I forgot to mention, when you say it runs sweet some of the time it should be something simple. It runs sweet always, except when it won't start. It's all or nothing unfortunately.

Post by **Variablevalves suck** » Mon Feb 23, 2009 7:05 pm

LOL- if youve had a Lambretta you should be a top mechanic, i raced a GP200 about 20 odd years ago and it never worked, If you know abit about electronics you may understand some of the link below relating to fixing a Bandit 400 which is very similar.
http://forums.banditalley.net/index.php?topic=10585.0" onclick="window.open(this.href);return false;
The transistors will work or not but if the caps are on their way out do you think the bike will come and go? its 25 years since i did an HND and dont remember D'oh!

Jaicen · Post by **Jaicen** » Mon Feb 23, 2009 11:57 pm

Hehe, to be honest my Lammie is a lot more reliable than the Gixxer so far! Although a clutch spring has just gone, so that's gonna need some fixing.
I think the caps could be responsible for the problem. Certainly i've had trouble with a/v equipment when electrolytic caps start to break down.

Post by **Variablevalves suck** » Tue Feb 24, 2009 10:03 pm

Its the last place id look, i think its something else being on and off. The ignition barrel worn, broken wire etc. Post your cdi part No. ive got some test data for odd 400 suzuki cdis somewhere, i'll dig and see if any match.

Jaicen · Post by **Jaicen** » Wed Feb 25, 2009 1:43 am

Well i've had a look, and all the wiring appears sound as far as I can tell. I figure it's the CDI as i've read a lot on the bandit 400 forums and many people seem to be having similar (identical!) issues which are solved by a CDI repair.

My CDI is part number 32900-35D20 BB7261

Jaicen · Post by **Jaicen** » Wed Feb 25, 2009 12:46 pm

Ok gents, things i've learned today:

1: I need more patience
2: Copper slip should not be used on electrical connectors!

Seems like i've sorted the problem. I got in touch with the seller of the bike, there was a 3-pin connector under the seat that had been causing grief with corrosion or something, so he cleaned it up and put copper slip on to stop it happening again. Unfortunately, when the bike has got warm, this has run and was causing a slight short on the connectors. I cleaned it off, turned it on and it started immediately! And I mean, literally on the button, no cranking, it just went from off to on. It's never started that well since I had it.
However, before he got back to me I'd already started removing the potting from my CDI to expose the innards. I've got to the electrolytics, at least two of which may be suspect so i'll replace them since i've come this far. I would STRONGLY advise against anyone attempting to get into one of these black boxes, they're a nightmare of silicone sealant! If anyone's interested, I can take some pics before I box it up again.

Common faults (GK76a Won't Start!)

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