mz rt 125 blowing fuse

[kev]

As on yours dave the blue goes to purple and red to brown.
with button pushed down i am getting no power to either connection (apart from the main that runs to battery +v.


and on this bit (is the coil) i get no reading here either yet

[kev]

I am yet to have the problem of blowing any fuses too, so i have no idea why that was happening. all i get is a click in the relay and nothing else, why is the starter motor not turning over when i do this, i also have no spark. im starting to think its the cdi unit???

[DAVID THOMPSON]

should be no spark till starter motor runs making motor timing sensor send signal to cdi box

[kev]

by bypassing relay 19 like dave said, ive finally got to where my friend was with the fuse blowing, so at least i now know i need a new relay,next step is to find the fault as to why the fuse is blowing so will go back to previous posts and start fault finding again.

ive also now stripped and cleaned carb, fitted new sprockets and now trying to find a link to put the new chain on, we're not far away now.

can anyone verify if this relay is the same as one as vw use in car window wiper systems? if i search for relay 19 that is what it comes up with.

[kev]

checked all the main +ve and -ve cables up and down and i happy they are all making good connection. to rule out the problem of a dodgy starter button i have gut the wires and connecting them myself, by twisting together what ive found is, that the main fuse blows as soon as i connect the purple wire that goes to the starter solenoid to the rest of the starter button wires.

remembering that now i have bypassed relay 19, where do i go from here folks

[kev]

somehow ive solved the blowing fuse problem, what we dont yet have is a spark, i have ht lead out connected to a plug which i am holding close to the engine to offer it an earth(i think thats the way to do it?) and as engine turns over and all sounds as i would expect, i get no spark, i have put multimeter on the wires leading to coil from cdi and have a reading of 0.03v probably not what the coils requires,

[kev]

ht lead looks corroded,not convinced im getting enough power there either, whats the best replacement coil for these?

[kev]

so with engine turning over and multi meter connected to the wires from cdi unit, what reading should i be getting from those wires? im getting next to nothing, this is the last hurdle now before its running,

[kev]

david, i think this is the diode u were on about, after more tweaking, replacing terminals and getting better connections all round, i managed to get the blowing fuse back, and also this diode, smoking.


i shall get to my local electronics shop in the week hopefully and replace this.
do you reckon this could well of been the original problem?

[DAVID THOMPSON]

show everyone a better picture of where the diode is in the harness
take a pic from further away

on that diode after a close look at the wiring drawings with a friend he said its a Zener Diode

probably a 3 amp at 15volts
its to keep the reverse voltages spikes from the big starter relay from Blowing thing in the bike like the
light bulbs or forbid the cdi box (hope NOT)
grahams is probably only source for it
or a good radio/ TV repair guy
or a 1 watt with a 400 ohm resister in series
it needs to be there to protect the bulbs and other stuff in the bike
and it needs to be of good quality
dave

[kev]

ive since removed the diode so i can take it with me to electronic store tomorrow so pics not possible, its the diode which goes between the starter button and starter solenoid. purple and brown wires. number stamped on it are - 1N 5406

[DAVID THOMPSON]

not a zener then
same number 1n5406 made by many suppliers

[kev]

today i have replaced the diode and when i turn the engine over all seems ok untill we get to the coil end of things.

what voltage should be going to the coil?

im soon to be spending money on parts i may not need as part of the elimination process, it may just be the coil thats duff but may be the cdi

[DAVID THOMPSON]

WILL TRY TO GET YOU SOME VOLTAGE READINGS ON MINE
THIS WEEK END
DAVE

[kev]

thanks dave, will be a real help,
im going to try a new coil tomorrow as mines a bit suspect and i have a another idea of renewing all connectors, i would like to get this running this weekend, which is possible providing the cdi isnt faulty