Interesting Test results vs. running issues.. any ideas? (GS550 1980)

[Guest]

Hi All,

I appreciate the subject of stators, reg/rec's and coils is one of particular popularity (if thats the right word) on this forum, but having read through lots of previous threads as well as all the stator papers, i am still struggling with the running of my GS550E 1980. Without taking over someones thread i though i should start a new one.. although if this is the wrong thing to do, i will happily remove and add this to an existing thread.

i will try to summarize my symptoms simply below:

1. Bike starts easily from cold, and runs smoothly at idle (14/1500RPM), with lights off. With lights on, the bike runs ok at idle for 10 seconds then slowly fizzles out and stalls.
2. after starting several times the bike becomes more reluctant to start.
3. It only seems to fire when the starter button is released, and slowly creeps to life.
4. when out for a ride on the weekend, the bike seemed to drop a couple of cylinders when running this was intermittent, however at traffic lights i maintained revs at 2500rpm so not to stall as I knew the bike would refuse to start if it cut out.
5. When i pulled in at a garage the bike cut out, and i was unable to start the bike again, not even by bump starting. When i pulled a spark plug out (clutch side end plug) the plug didnt appear to spark as often as the engine was turning over. the battery was still strong, and the engine was turning over as quickly as usual.

After being recovered to home, i removed the battery and put it on charge overnight. The battery is only a few weeks old and this was the first ride out using it, infact my first ride out on the bike since owning it!



This evening i have run the 6 quick electrical tests both with lights on and off. See results below.


1.) key off................12.76V (same for both)

2.) key on (but not cranking with lights for 10 sec).....Lights off - 12.41V Lights On - 12.20V

3.) at idle (1500 rpm).....Lights off - 12.94V Lights On - 12.70V

4.) at 2500 rpm Lights off - 13.90V Lights On - 14.28V

5.) at 5000 rpm.....Lights off - 14.44V Lights On - 14.37

6.) key off..... - 13.0V


I can't see much wrong with these results, but if anyone has any ideas or possible further tests i can run to try and track down whats wrong with the bike i would be very grateful.


Many thanks in advance, and sorry to you knowledgeable guys out there who have no doubt problem solved these issues for hundreds of bikes...


Matt

[60ratrod]

i would suggest checking the resistance of the coils, checking to make sure you're getting the full 12vdc from the switched hot wire(should be orange with a white stripe), and check the resistance on the plug caps. these are all of the things i look at with my bikes, and found a bad cap on my kz1000m1, and eventually a bad ignitor on my 81 gs650g. from what you're saying, i would check the resistance on the plug caps, the resistance on the coils, 12vdc(engine off, key and kill switch on) at the coils, the resistance of the pulser coils, and then finally check the ignitor. my guess is it's the plug caps, but again, it's just my guess

[BigD_83]

i don't see anything "wrong", but I find the results at 2500rpm interesting. It's the only rpm at which the recorded voltage is higher with the lights on than the lights off.

Other than that, it looks like it is charging well enough.

The note that it only seems to start when you release the starter button rings a bell, but I can't quite recall what/who it is that I am thinking of.

The symptomology while running sounds an awful lot like a coil or R/R dying when it heats up.

It could even be a stator going out on you so it would be time to move on with your electrical testing.

This thread would be a good starting point:

http://www.thegsresources.com/_forum/showpost.php?p=1138531&postcount=1

[tkent02]

[*]It only seems to fire when the starter button is released, and slowly creeps to life.

This is key. The battery for whatever reason isn't putting enough power to turn the starter and run the ignition both. When you let go of the starter button, the ignition suddenly gets enough voltage and starts to work, the engine starts to run.

Electrical connections somewhere between the battery and the starter or between the battery and the ignition are not clean enough. Too much resistance somewhere, or the starter or the battery could be bad. I'd start with connections.

Do this, check the voltage at the coils while the starter is cranking.

I bet it's low, for the electronic ignition systems in the 1980 GSes about ten volts is as low as it can go and still spark, maybe even higher.

[posplayr]

Seems mysterious, but doesn't seem to be charging. Even if the the stator had a temperature sensitivity the battery is strong enough to maintain voltage unless the voltage drop to coils is so high , that this thing is definitely marginal. As recommended check the voltage to the coils. If I had to guess the ignitor is going out given weak spark while cranking.

Don't understand the bit about firing only after start button was released because the battery holds up the whole system including headlamp at 12.2V. Double check what is at the coils.

[Gadgetboy550]

Thanks all, Will be back shortly with test results.

[Gadgetboy550]

I have run several of the suggested tests this evening and the results are as follows.

First Coil (LHS Bike)
Voltage at coils when cranking - 7.20V Lights off 6.30V Lights on
Running/not cranking over - 10.40v

Second coil (RHS bike)
Voltage at coils when cranking - 7.20v Lights off 6.30v Lights on
Running/Not cranking over - 10.40v

Cylinders from Left to Right facing forwards (as seated).

LHS Coil - cylinders 1 & 4
RHS Coil - cylinders 2 & 3

I assume this is correct!

Finally, Resistance on coils Cylinders from Left to Right facing forwards (as seated).

1- 5.0K
2- 5.70K
3- 4.90k
4- 4.54k

Hope this leads us somewhere, Obviously the voltage is very low to the coils.. which isn't good.

Look forward to hearing what people think.

Cheers,

Matt

[Jptech11]

I might be talking out of my ass but the capacitors inside your igniter might be starting to dry out not holding complete energy as they used to. Try borrowing an igniter. basically regulators need changing i mean you can get a new one with 3 phases for 50 bucks free shipping. sounds like alot but we spend that kinda money on dumb stuff anyway right. the igniter thats another story. try but you can get a european made copy of the exact thing from a company called ah i forgot but search gs450 igniter on ebay and youl see it for 175 bucks. they have even copys of chinese 5 pin cdi's made in europe. legit company try it out. might help if youre searching for one WITH A WARRANTY

[Jptech11]

No i thought about it. Its most likely the r/r

its like this

l------------spark
-----battery---regulator----cdi/igniter-10v?coil10v here?
l l l combu
l l l energy
l --------------------------- stator
-------------------------------------------l

[Jptech11]

ok that came out all wrong

[Jptech11]

...............

[Gadgetboy550]

I have got to say, I am now completely confused!! can anyone make sense of the test results i posted?

JPtech11, thanks for the response, its just i am now left without any idea where i am! haha

Thanks,

Matt

[OldVet66]

Go through the entire electrical system and clean all connectors, switches, plugs, grounds and fuse box, coat all connections with dielectric grease and replace any burnt connections where the wire insulation has gotten hard and brittle. You will be chasing your tail until you remove the cumulative high contact resistances built up in the electrical system due to corrosion. Pay particular attention to the grounds and possible broken wire strands in the heavier cables hidden by the wire terminals. Then your test results will mean something if it doesn't inadvertently fix your problem.

[posplayr]

Cleaning electrical connections means using a chemical contact cleaner. If it is really bad use a brush. Deoxit is good.
if your coil voltage is that bad I would start by hot wiring the coils direct through a fused switch from the battery to see if that fixes the problem. If it does go back to cleaning your connections. If not if could be an intermittent ignitor. And intermittent R/r is possible I guess but you would not be seeing the same symptoms.

[Gadgetboy550]

[QUOTE- if your coil voltage is that bad I would start by hot wiring the coils direct through a fused switch from the battery to see if that fixes the problem.[/QUOTE]

Thanks for the comments, What rating Fuse would you put inline for this hot wire Posplayr?

Would never have thought of that as an initial test, but will certainly try it then clean up all the connections.

Cheers.

Matt