Author Topic: intermittant spark (Read 3486 times)

skolviking · « **on:** December 30, 2005, 07:31:13 AM »

Hi I have a it of a problem with my bike, all to do with the spark

Ill crank it over and it catches and runs for 1/2 a second or so then dies with no spark, and the spark doesnt return unless i leave it for 30 mins or so.
theres no spark on both sets of coils.

Occasionally it will start and run, once its going and warm it hasnt died like this, it only seems to be a startup problem.

The CDI is good, I have 2 and one had been tested by a company, i have an oscilliscope trace to show its working properly. The traces show nice 12v signal with dips where they should be for spark.

I have topped up the battery and charged it overnight, and to stop it draining too much i normally crank it over with the charger attached.

I have checked the continuity of the spark signal wires, from CDI to coils. and timing signal wires from crank sensor to CDI. And the earth wires.

There is always 12V on bith wires in to the coils when the ignition is on.

Any more ideas out there?
It seems to me that the coils arent getting the dip in the signal to create a spark.
Could it be my battery is too old and a brand new one is needed?
Is there anything else in the system that could cause me problems?
Im thinking crank sensor, its resistance seems a little low but just within tolerence are there any good ways to test this?

Cheers
Matt

Farre · « **Reply #1 on:** December 30, 2005, 07:44:24 AM »

What about the spark plugs? Are they in good shape? Is the gap distance correct?
Spark is heavily dependant on those factors as well..

Zhi · « **Reply #2 on:** December 30, 2005, 12:11:54 PM »

I've had this problem before, so I'd say it is most likely your battery.

skolviking · « **Reply #3 on:** December 30, 2005, 01:22:58 PM »

Thanks for the ideas,

Plugs are good, i have 2 sets, same problem with both.

In my mind i keep going back to the battery, i dont know if its too tired and cranking it drops the volts too much weakening the spark to the extent that it doesnt work.

Ill try connecting a spare car battery in series to back up the little bike one, see if that makes a difference

pmackie · « **Reply #4 on:** December 30, 2005, 01:35:56 PM »

Also, check all your wiring and especially connections. Take all connectors apart, clean them with contact cleaner, etc.

The battery is the first thing to make sure it's OK, but it is possible that youv'e got some damaged or poor connections.

skolviking · « **Reply #5 on:** December 31, 2005, 01:40:08 PM »

well thanks for all te help, in the end i traced it to the signal generator whach was producing a tiny signal, sometimes the CDi picked it up sometimes it didnt.

This is quite strange because the sensor was sopt on as far and the manual is concerned, it is 100ohms, bang in the middle of its tolerence.

Thanks again

Matt

doqq · « **Reply #6 on:** January 22, 2006, 08:18:43 PM »

would the signal generator be the same as the pulse generator? i had the same problem you described but my mechanic can not figure it out. but he did say it could be the cdi or the pulse generator. so are they the same?

Herr Tod · « **Reply #7 on:** January 22, 2006, 09:14:56 PM »

A pulse is an individual electric signal, so yes it is the same

skolviking · « **Reply #8 on:** January 23, 2006, 05:49:42 AM »

to me they are different although my terminology may be wrong,

the signal generator is a component that sits in the LHS engine casing and sends a signal to the CDI as the crank spins

The CDI picks up this signal and from it sends the spark pulses at the correct times

matt

gsxr400 racer · « **Reply #9 on:** January 23, 2006, 11:00:27 PM »

yes those are the same thing those are both term for the pulse generator ,signal generator , pick up coil !~