gs750 dyna s problem

mobcharge

mobcharge

New Member
desperate plea for help before i send my new dyna s back.

I have 12,4 at the battery
The coils are a set of newer accel 3ohms i borrowed, tested them to 3.5 each and about 13,5 so all good, the wires are brand new dyna.

So plus side on the coils (orange white wire from the kill switch) is a healthy 12.2 (the same orange white wires is hooked to the red dyna wires, switched possitive)
At the minus side, black and white wire, i have 12.2 too, if i disconnect the white and black and just check between ground and them i have 6v from one and 4 from the other, if i rotate it by hand it drops to 0 once each revolution, still 12.2 on the actul coil.

That seems very strange, they should read very low and then go up to full 12v once each revolution and that would
be when it spark right?
If the modules are messed up they'd be totally dead you'd think and not work "backwards".. i have looked high and low and either i am super dumb or no one has had this problem.. Am i missing something obvious, can a weird short or ground issue
be behind it?

If something is unclear just ask and ill straighten it out, it ran fine, then my dyna died one my way home one day, wired in the new one and it never worked
at all. Dyna says the new one was tested.. I really dont want to wait for more than a week just for them to get it, then another week before testing etc..

did talk to dyna, they don't know either, its the 6v from one module and 4v from one constantly that worries me.
me and makes me think the dyna is to blame.. Then again when they go bad, like my old one (dyna tested and confirmed) they do nothing, not signal no nothing
here i got a drop every time the magnet passes the module..
I've re soldered and rewired a lot already but will do more today to make sure there is nothing wonky going on.
The thing is the bike was working great before then one module died on my old dyna, i installed this one and no no spark, makes me think its the problem.
 
I never bothered to check the voltages on any Dyna, but does it make sparks when you turn the motor ( or the rotor)?

If you use a small test lamp does it go ON when the rotor gets to the timing mark?
 
You mentiuoned thast this is a replacement system, so a failure on both modules would be most unusual. Are the coils OK in terms of wiring to the Dyna and resistance. You mention they are new Accel at 3.5 ohm primary and 13.5K ohm secondary - at least that's what I think you said. Did you try your old coils?

If the old S worked fine until it didn't, that suggests that either the S module burned out, or something caused it and the new units to fail. If it's not running it can't be the alternator or regulator. Are the S modules wired back to front by any chance? Agree that would be hard to do. Dyna S Red to switched 12v and the white and black leads to the coils.

The way that the circuit works is power to coils to Dyna to Ground (when it switches). If the light is on all the time, is it possible that the engine ground lead is broken or has a poor connection?

You said no spark, so it's not that the timing pin dropped out and timing is out of place. One simple test is to remove teh rotor and put it back on teh shaft inside out so you can spin it back and forwards between your fingers. With power on, it should spark with each reversal of direction as the magnet passes the trigger.

I don't suppose the magnet(s) came loose and dropped out did it/they. That would be unusual, but I think we are looking for something that happened when you were riding it last time.
 
teazer said:
You mentiuoned thast this is a replacement system, so a failure on both modules would be most unusual. Are the coils OK in terms of wiring to the Dyna and resistance. You mention they are new Accel at 3.5 ohm primary and 13.5K ohm secondary - at least that's what I think you said. Did you try your old coils?

Yeah its a replacement for my old one when ONE module went bad, dyna confirmed.
the coils resistance was 3.5ohm and 13,5k yes, can rememeber what the old ones tested but the secondary differed to much and
i picked up theese ones cheap (accel). Yes they are wired as follow. live lead from confirmed working kill switch goes to both the coils, then white from dyna goes to other left coil terminal and black to other right terminal. thats is.
Tried old coils. nothing.


If the old S worked fine until it didn't, that suggests that either the S module burned out, or something caused it and the new units to fail. If it's not running it can't be the alternator or regulator. Are the S modules wired back to front by any chance? Agree that would be hard to do. Dyna S Red to switched 12v and the white and black leads to the coils.

See above, wired right

The way that the circuit works is power to coils to Dyna to Ground (when it switches). If the light is on all the time, is it possible that the engine ground lead is broken or has a poor connection?

That what it normally is, but if i take the white and black wires of, still power wires to the coils and the dyna i get 4v out of 1 and 6 out of the other. IF i unscew the dyna and let it hang freely, no ground, it jumps straight up to 12 volt on both as it should.
the ground is fine, i even just to make sure ran a cable from the dynas mounting plate straight to the main fround point, no diffeence. ive tried to power (temporary) the dynas red cable staight from the battery and the coils from the switched power and vice versa, same thing.


You said no spark, so it's not that the timing pin dropped out and timing is out of place. One simple test is to remove teh rotor and put it back on teh shaft inside out so you can spin it back and forwards between your fingers. With power on, it should spark with each reversal of direction as the magnet passes the trigger.

No spark in any plugs, will try that, but even if the timings was totally off there should be a spark, i could hold the plug in my hand if i wanted to.

I don't suppose the magnet(s) came loose and dropped out did it/they. That would be unusual, but I think we are looking for something that happened when you were riding it last time.

No nothing like that, I rode it home on the two working cylinders.
The reason i just didnt send it back right away, im not that inexperienced wrenching after all, is that if its dead you get nothing/

i get 4 and 6 volts which drops to 0.1 or something each revolution if i turned it by hand.
as long as i have power on and 12v going into the coil i also have 12 volts on the "minus" side (white or black wires hooked too)
i have to take the wires of to get the 4 and 6, also if i leave it all on and meassure the minus side nothing happens.

So stuff is happening in both the modules but nothing that is helping me getting a spark...
Click to expand...
 
also my old dyna was a used one that turned out to be 18 years old when failing..
i installed it and rode the bike for a year .
 
At this point I'd send it back to Dynatech and ask them to check it out. They do say that you can't test it for voltage or resistance.
 
Yeah i did late yesterday afternoon after yet another day of going trough every single part of my electrical system, should be bullet proof by now..
 
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