gt750 condensor failure and timing question

[chance johns]

i have new points and condensors on my gt750. i havent had this bike up and running very long, but ive had it on quit a few test rides and its been ok. recently its been sputtery and my first inkling is to check the spark. and check the points.

my L set of points are arcing out of control.

i could replace this condensor and correct it, but it will probably just happen again. what would cause this to fail.
this is what i know.

heat: if this condenser got too hot it would make it fail. BUT it doesnt make sense that this one spot got too hot and the other condensers right next to it didnt get as hot and didnt fail.

ground: if this condenser has a bad ground it would fail. its new the plate its bolted to is clean. not the issue here.

bad from factory: it could be faulty from the start....but i had a couple handfuls of good runs so it was working properly for some time.

what else could i be checking? the condenser has relation to only the points and ground,correct?




TIMING QUESTION.

SO theres a window on the points plate and through that window there are timing indicators. should the points just start to open at this mark as indicated per cylinder? the manual requires a dial indicator which i do not have, and is expensive. if i have to buy this i will, but whats the point of this window if not to set the timing?

K THANKS

[Coyote]

Yes. The points should just be opening at the mark you see through the timing plate window. If it does not, you need to rotate the plate for the left and the points themselves for the right and center. Always start with the left as rotating the plate will affect the other cylinders as well. Once you rotate the plate to set the left, it does not move again.

[Vintageman]

ground: if this condenser has a bad ground it would fail

If the condenser was not grounded, it would not cause the condenser itself to fail. It would prevent the condenser (a capacitor) from doing its job of sucking away the coils inductive current spike quickly and keeping the voltage across the point low.

The spike occurs when the current flowing through primary side of coil is disrupted as the points open. The condenser sucks up this energy which would otherwise be seen across the points. Every coil has some leakage inductance and why a spike and a reason why a condenser is needed across the point set to shunt away electrical energy that would otherwise burn up the points .

If truly the condenser is good quality (large enough value for example) well grounded, and other side connected to points proper and say one point sets burns up quickly my guess is the associated coil has too much leakage inductance (more than normal). That means the coil primary to secondary side coupling is getting poor ... large inductive kick when points open ... AKA failing coil. Can't say I have seen this but, it is theory if all else is really OK.

[chance johns]

what is the order of operation with the current flow?
battery-coil-condenser-points-coil-high tensionlead/plug?

so if my new condenser is failing and ive ruled out ground/excessive heat/point connection, then i should test my coils?

ive done this on my gt550, and i think ive done this on my 750 but i could be mistaken. can somebody refresh my memory on how to do a proper resistance check for my coils?

is a resistance check the only way to test the coils?

[GT750Battleship]

Hi,"bin" the points & go Electronic,I've just fitted the Accent System to my A model,best thing I've done in a while,idles sweetly when hot & cold...more responsive to the throttle
Regards,
Roger

[Alan H]

Just fit another condenser. THE CORRECT TYPE.
They don't last forever and the one you have may be 40+ years old.
They are oil filled and dry out with age.

[chance johns]

roger, I DONT SPEAK AUSTRALIAN.

[GT750Battleship]

Nothing wrong with points & condensers,except for the maintenance & checking timing as things wear,Suzuki genuine point set now $47 dollars for one!! plus condensers & this all adds up,guess I'm trying to cut down on maintenance time by fiddling with points,hope you get the bike running well soon
Cheers,
Roger

[Vintageman]

Change Johns

I know you said you changed all points and condensers. Did you use OEM or aftermarket parts. Usually Aftermarket points are not as good typically wear out sooner.

Are all three points failing too soon? or just one set?
I read that only the "L" one is failing. So that is odd

Again if everything is 100% good with points and condenser and grounding and good quality, yes question that one coil attached to "L" points. Leakage inductance can be measure roughly by shorting secondary and measuring the inductance and the primary,,, if you have an inductance meter and a specification. If this was the issue it probably was the case day one and has trouble a lot of people since as to why only after a relatively short time after changing points the engine starts to run like poop.

Coil Resistance measurements are easier to do and would give a clue as well... maybe the coil is shorting and too much current through primary... more common failure mode

If the points and condenser are good, connected correctly, what else can it be? Coil bad internal or the high tension lead from coil to plug is open (measure resistance), Or maybe you are running a 24VDC battery (doubt it)

Verify points and condenser again and try swapping coils, check coil resistances or swap coils to see if problem follows the coil or stays with L points.

Let us know what you know