What Happens To a Starter Relay When its Fried? (and how i fried it twice!)

So this part of the story I can easily call “being cheap”, because I steered away from the problem, and bumped into another because I picked up a cheap replacement part! 

Just to be clear, I have nothing against cheap Chinese parts, because most are made there anyway and are absolutely fine, however, now and then we bump into stuff that is made less than adequate, and then we pay the price for it!

Picture: all parts of the relay

For those who have no idea what Starter Relay, or Starter Solenoid is, it’s basically a switch that can be triggered remotely if you like! In short, instead of running 100A (or so) rated wires from the battery to the starter button on the handlebars and all the way to the starter motor, or moving starter button closer to the starter or battery itself (obviously beefier switch would be needed for that too), it allows to run thick wires only from battery to starter motor via Starter Relay that is triggered by a switch on the handlebars using a lot thinner wires – saving a lot of weight and money for manufacturers…  And construction of the Starter Relay is, well it’s  nothing but an electromagnet that once activated – pushes a metal rod to make a contact between battery and starter motor terminals – completing the electrical circuit in order to make a starter motor to spin.

Trouble is that inside of them there are moving parts, a lot of current passes its contacts, and with time they do wear out / burn out and do not function as they should – and that’s what happened with my old one… on the first start it would just click once, and only on the second attempt it would spin the starter motor – sign of bad contacts inside of the relay.

Luckily I already had a spare starter relay, so I didn’t waste any time and just replaced it, but… Not long after, my xt’s electronics would go off for no apparent reason and of course it had to be intermittent to make things more interesting to diagnose… once it just stalled a few meters from the parking spot at work, next time it stopped at the traffic lights.. XT’s electrics would go off and on at completely random times!

Checked fuses and connections and found out that the 4 wire plug that goes from the main wiring loom to the starter relay has something to do with it. Since the relay was new and working, I didn’t even think that it would be it, instead, I thought it might be the wires, as they did get disturbed while changing the relay! 

Funny enough after taking all the protective layers of that part of the wiring loom, I found nothing. Cleaned the plug itself and the relay connections, and after a good look at the fuse, I found something I haven’t seen before – a fuse that looked like it was exposed to some heat! 

Now xt’s main 30 amp fuse is right on top of the relay itself, and it’s not for the starter motor just in case someone is wondering. It’s for all electrics of the bike. And that is fine, if construction of the relay unit is decent. However on that cheap relay, for whatever reason manufacturers used a very thin srip of copper strip to connect between the “power in” on the relay to the main fuse, and that is where it started to fail – heating up, oxidising, melting fuse too.. And when I say “melting fuse”, I mean one side of the plastic (green plastic in this case)  not the fusible element itself!

Picture: a bit blurred, but the difference of thickness is clear, left terminal from old relay, right from the new one.

And yeah, being cheap, I didn’t replace the whole relay unit once again – I took both of them apart and swapped the main fuse holder bit (that was burning up on the new relay) with the one from the old relay unit, as it was made from a lot thicker material! 

So here it is, the difference between the cheap and not so cheap  is in the materials used!

Explore More!


All Yamaha XT660Z faults and hiccups that left me scratching my head.

  1. How to fix rattling headlight reflector
  2. How the regulator rectifier overcharged my Tenere’s battery.
  3. Funny oil leak, or how i lost 1 liter of oil in 500 miles.
  4. Funny story: how my XT660Z fuel reserve light tricked me, leaving me stranded!
  5. How the starter relay got fried twice on my xt660z!
  6. How I fixed a squeaky / rattly dash on my xt660z!

All Yamaha XT660Z Mods!

Recommend this article on:
Scroll to Top