Bought a Bandit 250: No Spark Diagnosis / Strange spark problem

Hi guys,

New here; first of all a huge thanks to the whole community and contributors, without sites like this I never would have had the balls undertaken this endeavour! I'm not a mechanic or anything like that, as will become apparent.


I bought a 1994 GSF250 (R) GJ74A with "a bad CDI" for a steal. I've been troubleshooting the bike all morning and have finally got some a clue about the lack of spark.

I replaced the CDI, and firstly got no spark from any of the four leads. This was true for both coils (1,4 and 2,3). However, after removing and shorting a faulty kickstand kill switch, I managed to get a consistent spark... but NOT while cranking.

A spark will only appear (a healthy, single spark, from any lead to be tested) exactly 4 seconds after I stop cranking the starter.

This makes me think that something between the timing signal from the alternator pickup/Crank Position Sensor and the CDI coil driver switch thing is not doing its job. Basically it seems like the capacitors receive enough power from the battery for the spark, but are never triggered to release it and then dump their charge when safe (4 sec delay).

I've read through the DIY CDI repair post on another forum, and want to cover other simpler fixes before I try to replace the Coil Driver Transistor (bit in the CDI that receives the signal from the Crank Position Sensor/Alternator pickup thing and tells the CDI to release the spark).

I tested the Brown and Black/Blue lead coming from the alternator pickup, and when cranking it seems to put out about 1.2V but I can't tell if its a consistent 1.2V or pulsing with correct timing.
Without cranking, the resistance between the same Brown and Black/Blue wiring pair is 348 Ohms which is within range according to that Synapse japanese tech data site (sorry no links for 7 days)

I'm way over my head here so any help is welcome!

Welcome to the forum bandithat, I'm sure you'll get plenty of good advice in no time at all, good luck with the diagnosis and repairs.

Welcome bandithat.  Sorry, can't help with a 250 problem as I have no experience with those machines.

PS: where do you hail from?

Thanks guys! 
Living in Maroubra at the moment, bike is at parents place due to lack of garage.

What are used CDI units worth? 
I'd be thinking a swap would be easier than ddismantling.  In any case are you sure the ignition isn't 180 deg out?
Hopefully someone on here will have had some experience with the baby Bandit which are good bikes when going.

Count the easy stuff out first. Side stand and clutch switch are two things that'll stop spark.  As will a crappy kill switch or ignition barrel

In just wondering how you test for spark. I presume you are grounding the spark plug electrode somehow? Of not you'll definitely have no spark.

I am sure the bandit shares the same motor as the across. Here's the across manual http://suzukiacross.org/downloads/

Thanks for all the replies guys!

So in my effort to carefully buy the right CDI I bought the wrong CDI like an idiot. (I bought a 32900-11D00 instead of a 32900-11D10). In a similar error I failed to notice that this site is focused on Bandit 1250's- so I appreciate your help all the more!

Reddog (that movie made me want an Australian Cattle Dog so damn bad): I've been testing via a screwdriver stuck in the plug end of the spark leads, held close to the block (~1cm). I've done the same with the spark plug grounded in the block.

I've found a US Supplier of new CDI units for around $350 posted to me. Decided to go with this over an old unit given their propensity to fail, and eliminating problems.

I have the battery hooked up to a trickle charger for now, was jumping off my car previously.

Given the sparks that I got before, I'm hoping that the coils are in good nick; one did require a solder repair under the rubber boot (so hopefully the rubber boot will stop any leak of spark).

Until the new CDI arrives the project is on turtle!