It wont's start !!

[flash gordon]

I've only had my gsx750f for a few weeks and I've never had it on the road but it has always started on the button.


This morning I started it and again it started on the button. However, a short time later I tried to start it but it did not spin over as fast as it usually did, so I put it on charge for a few hours. When it was fully charged I tried it again and the engine turned over at a good speed but wouldn't start. With no choke and minimal throttle it felt like the engine wanted to try to start as it would fire just now and again. I don't know if the problem is fuel or ignition related.


I've checked the plugs and they spark but the spark isn't a nice deep blue spark that I would expect.


Which parts do I need to look at to get it going again? Why is it affecting all the cylinders ?


It just seems strange how this happened all of a sudden!!


Any help appreciated.

[Kreylyn]

I've only had my gsx750f for a few weeks and I've never had it on the road but it has always started on the button.


This morning I started it and again it started on the button. However, a short time later I tried to start it but it did not spin over as fast as it usually did, so I put it on charge for a few hours. When it was fully charged I tried it again and the engine turned over at a good speed but wouldn't start. With no choke and minimal throttle it felt like the engine wanted to try to start as it would fire just now and again. I don't know if the problem is fuel or ignition related.


I've checked the plugs and they spark but the spark isn't a nice deep blue spark that I would expect.


Which parts do I need to look at to get it going again? Why is it affecting all the cylinders ?


It just seems strange how this happened all of a sudden!!


Any help appreciated.

Lets do some simple tests to narrow down issues.


First test - use a digital volt meter and test the voltage at the coils when the key is on, and when the starter is turning the motor over.


That should give you 8 results... 2 for each of the 4 wires.


If any of those are below 11v, then your going to have starting issues and you will need to track down the voltage loss issue.


krey

[flash gordon]

Thanks...sorry for late reply as I do long shifts!!


Anyway here goes. Battery had been on charge overnight prior to test. I've cleaned the connections at the battery, starter relay, stop switch, the terminals on the black plastic box on the side of the battery holder and coils.


Ignition off battery 12.65 v
Ignition on battery 12.20 v lights on


Coil 1


Orange/white wire ign on 11.44v ; cranking 9.6v
other wire ign on 0v; cranking 0.2v


primary resistance 3.2 Ohm secondary 34900 Ohms


Coil 2

Orange/white wire ign on 11.42v; cranking 9.83v
other wire ign on 0v; cranking 0.17v


primary resistance 3.2 Ohms secondary 35400 Ohms


When a new wire connected to battery positive to coil 1 showed 11.00v on cranking but would not start.
Obviously the non orange/white wires to the coils are very low. The neutral light is on.


Any more help appreciated!! Thanks.

[Kreylyn]

Your battery is on it's way out. Replacement is probably necessary. It's failing the load test, and that is why you see the voltage drop down to 9 or so. This could be exasperating another issue though...


My next test would be to locate and borrow if possible a known good CDI and swap, redo the electrical test you posted and of course check if it will run.


The extremely low voltage on the signal wires is disconcerting and problematic. That combined with a weak battery I think is combining to make the bike not run at this time.


Krey

[flash gordon]

Thanks for the reply.
Is there any way of testing the cdi unit and the signal generator?

[Kreylyn]

Thanks for the reply.
Is there any way of testing the cdi unit and the signal generator?

There is a simple test for the signal gen in the manual.


The CDI requires specialized equipment to test, and generally isn't something that most shops now days have on hand.. if they did even prior. If you can't find someone local-ish that may be able to offer a loaner to test with, then you can probably find a used one to purchase cheaper than paying for a "test" to be done.


Krey

[flash gordon]

Cheers.


The signal generator checked out fine.


I'll get a battery and a cdi unit. TBH I'm no speed junkie ...I ride like a District Nurse. My bike's a 750 but will a CDI from a 600 or any other models from the Suzuki range fit and work OK ? I'm not bothered about rev-limiters as long as it runs properly !!

[Kreylyn]

Cheers.


The signal generator checked out fine.


I'll get a battery and a cdi unit. TBH I'm no speed junkie ...I ride like a District Nurse. My bike's a 750 but will a CDI from a 600 or any other models from the Suzuki range fit and work OK ? I'm not bothered about rev-limiters as long as it runs properly !!

For the test, it will be all about matching the connectors at the cdi. I don't have a list of those to match up by. Sorry. I suggest taking yours with or verify by pics before committing.

Krey

[flash gordon]

No probs.

I didn't know if different engines have different ignition characteristics even though the external features are similar !!

Cheers.

[GSXFJim]

I'd start with a new battery before spending $ on a cdi...

[rexazz2]

I'd start with a new battery before spending $ on a cdi...

and fresh spark plugs

[flash gordon]

For reference.. all sorted, it was the battery !!

Thanks everyone.

[Taybiker]

Good to hear your all sorted now

[zwieringa]

Had same prob