Mastiff engine wouldn't stop!!!

[tedthebudgie]

Have just come back from a 60 mile ride on my Mastiff with a few stops along the way. Started and stopped no problem. About a mile from home engine started making a nasty rasping sound so bad that my wife came out from the house to check what was up. I put it in neutral and turned the key to turn off the engine but it kept going. Stuck it into first and couldn't stall it. Kill switch didn't work. Turned off the fuel and waited until the engine died. Tried starting it again but nothing apart from a click from the starter relay when the starter button is pressed. Neutral light and electrics all working. The starter relay was very, very hot and some of the plastic shroud had melted. Obviously, I will try another starter relay.

I just wanted to check whether something might have caused the starter relay to fail like this or might it simply be knackered given it's 21 years old (9,000 miles on the bike)? Any idea whether a failed starter relay would make the engine continue to run with the key removed from the ignition and the kill switch on?

[DAVID THOMPSON]

check relay 19/30 on mz drawings if its contacts stuck it may be the problem

or the start relay may have welded its BIG contacts together
and your battery took a bad hit if this happened
battery may still work but it may be short lived
relay 30/19 has red/black wire /red/white wire and and a green wire every thing in the bike goes threw it
sounds like its contacts are stuck in run mode
click to see drawing larger or download and print a copy
dave

[tedthebudgie]

Thanks Dave. Much appreciated.

[DAVID THOMPSON]

Halfords has relays the green wire has a too small spade lug for most relays

the oem relay is too small and does not cool well
dave