2002 Mastiff owner needs advice! Please!

[nathanfinkel]

Hi all,

new to the forum, and at my wit's end with this bike. If anyone can help, please say!


I have a 2002 Mastiff which has been mauled by the last owner and has been giving me no end of problems. I have literally been off road for months with various things. It's latest joy is the electrical system. The bike starts on the button but then cuts out (as if the killswitch has been pushed) straight away. If you continue to hold the starter button, it continues to work but then when you let go, it dies.
I have replaced:

Right handlebar controls
Solenoid
Stop Relay
Battery
Spark plug (several times)

I have just had the whole loom out and checked it, it seems fine. my bike is weird tho, the fan's gone and it doesn't have the 7.5A fan fuse among other things. But this particular problem is new and recent and came out of nowhere.

I have a wiring diagram and SZR660 workshop manual but am running out of ideas. Please help!

Thanks!

[nathanfinkel]

obviously checked and changed fuses too

[breakwellmz]

Sidestand cutout switch?

[DAVID THOMPSON]

PM sent
dave

[nathanfinkel]

OK, so completely mistified now...

DOES anyone know what type of 3A Diodes the bike has? It alledgedly has 3, mine has 0. i have heard they are shotkey or something? I just need to know to get some more.

Thanks!

[DAVID THOMPSON]

pm sent again on diode
link case anyone else needs
http://www.radioshack.com/product/index ... Id=2062579
may be over kill but will work
dave

[edis]

Sidestand cutout behaves just like that, unless you are in N.

[billr]

pm sent again on diode
link case anyone else needs
http://www.radioshack.com/product/index ... Id=2062579
may be over kill but will work
dave

Resurrecting this one, just had the "31" diode break.
Thanks for the link.
Bill R

[billtraveller]

Hi , I've had this problem on a different bike that was fitted with a ballast resistor on the ignition coil . When the starter is pressed the ignition supply bypassed the resistor ( which had failed ) & the bike started , when you released the button it stopped . The ignition supply / live can come from a different wire when the elec starter is energised . You will need to check the wiring diagram to see how the ignition supply is run with / without button pressed . I don't think the Yam engines have a resistor but it will be a problem with the normal live feed which is bypassed when you press the button . If the bike only had a kickstart it just wouldn't go & you could look for the bad joint in the wiring until you got your sparks back . There's nothing like a novice apprentice for checking if a plug has a spark !! Regards Bill .

[DAVID THOMPSON]

shame on you for trying to make some blokes eyes glow in the dark
by holding a spark plug wire

years ago it was a joke
with the high voltage of some systems on newer bikes
never handle spark wires
when cranking or running a modern bike
in fact read the labels on some of the bmw bikes
there under the seat in 6 or more languages
on at least 2 models i have seen
dave

[billr]

There's nothing like a novice apprentice for checking if a plug has a spark !! Regards Bill .

My dear grandfather..."Here, hold this up to the head...it won't do anything"...
It was a lawn mower and I only had to do that once...I learn quickly...
Bill R

[DAVID THOMPSON]

some of these NEW systems will not teach you
THEY WILL KILL YOU
and watch out for those electronic diesel fuel injectors
some of them have 150 plus volts on them in some applications
but even the low voltage ones have current flow levels that are very dangerous

i learned on grandmothers Maytag 2cycle washing machine
my whole arm was numb for several days about the summer of 1953
Dave