More Wakeup Juice With a Fan Cutoff Relay

As always with my mod and how-to write ups, a little speal divulging the inspiration: The bike was acting up every once in a while when I'd go start 'im up. Figuring it was another electrical gremlin, I started measuring voltages. Long story short, I found a broken ground terminal. Don't know if it was the root cause, but knock on wood, I haven't seen the problem in over 50 starts. During the hunt, I was studying the wiring diagram and realized that unlike the headlight circuit that is cut when the starter button is depressed, the fan remains connected to the battery and, if the temperature is right, spins through a startup sequence. Sure enough--after warming up the bike to get the fan spinning, I attached a voltmeter to the battery and restarted the bike. HOLY CRAP, as the bike faintly struggled as I coaxed it into service, the display dipped down into the high 9s--not exactly the high 9s that Maxxers shoot for. LOL. Anyways, I removed the fan fuse and restarted the bike. The voltmeter held true somewhere between high 10s and mid 11s and the bike fired up like it was rudely awakened and wanted to kick some ***.

So, I got to thinking and figured that the fan doesn't need to turn during the period it takes to fire up Max. The solution came pretty easy to me due to the work I did with my RFID mod. Failing to make a long story short, I spliced a relay between the fuse box and the fan and energized it using the starter relay's ground signal coming from the starter button.

Here's a schematic of the Single-Pole/Double-Throw relay


Here's a wiring diagram of how I inserted it into the bike's electrical system


Here's a couple of pics of the connectors I spliced into the fan line


Here's a couple of pics of the connectors attached to the SPDT. NOTE that pin 87 is left unconnected--I went so far as to shrink some plastic around the pin to insure no incidental contacts from whatever may happen. You don't want this connected to anything--especially NOT ground.


Here's a pic of the blue/white starter relay line that I connected SPDT Pin 86 to.


Here's a pic of the relay nestled next to the main fuse holder after encasing the terminals in a section of heatshrink and electrical tape to protect it from the salty Floridian air.


Alternatively, I figured up another configuration, but preferred what I ended up with, in favor of the relay coil not always being energized as what would be the case

Impressive - great deductive reasoning, Mr. Ninj!
Do you suppose that this could be contributing in part to the infamous "poor hot starting " problems experienced by many Maxes with the old 2-pole starter motors???

You know Miles, the thought did cross my mind. This afternoon while I was walking the dog, I thought about all the procedures that is done in order to maximize the charge in the battery to cure the "hot start" problem; and ended up wanting to convince myself that these helped the matter by getting the battery through the huge demand it experiences when the starved starter motor cranks. But I don't want to claim anything for sure without a storage oscilloscope. One thing for sure, as with all of the by-the-seat-of-my-pants measurements I rely on with my mods, this sucker now wakes up on "the wrong side of the bed". Hahahaha.

ninjaneer said:

You know Miles, the thought did cross my mind. This afternoon while I was walking the dog, I thought about all the procedures that is done in order to maximize the charge in the battery to cure the "hot start" problem; and ended up wanting to convince myself that these helped the matter by getting the battery through the huge demand it experiences when the starved starter motor cranks. But I don't want to claim anything for sure without a storage oscilloscope. One thing for sure, as with all of the by-the-seat-of-my-pants measurements I rely on with my mods, this sucker now wakes up on "the wrong side of the bed". Hahahaha.

Click to expand...

If the load demand from an energized fan was a contributing factor, would certainly be easy enough to confirm - if you could find an older bike with this problem. Just get 'er smokin' hot, shut 'er down, pull the feed wire off the fan motor. Then see what happens.
Have you measured the draw of a running fan with an ampmeter? Just curious.
And if it wasn't for wiring size and fusing arrangments, couldn't the brown thermo switch power supply wire simply be spliced into the red/yellow headlight fuse wire?
No, I take that back - not a good idea to have the fan and headlight on the same circuit . A safety concern.
Keep those ideas coming! Great work!

Nice neat job....good thinking! :thumbs up:

That is a GREAT idea. Well done Ninja! I live in a HOT climate too, so this will be invaluable in the coming summer months. :worthy:

Why couldn't Yamaha engineers thought of this years ago, good on ya Greg.........Joe

You da man!!....as usual....great idea....great implementation!!

Greg once again helps the VMax community. He has helped me personally, and now has potentially given all of us a way to protect our bike's function when starting. I suppose that you could use this on other Yamaha products too. I understand the procedure is not-only a Yamaha dysfunction. I think he should write it up & send it to the major magazines' tech sections, as this process could apply to any "electric foot" system where there are other draws electrically, and we need to spread the word. I coin the phrase, "Greg's Electric Leg Mod" to give it a catchy name to make him famous, at-least among we of the "V-Boost" persuasion. At least, it could become a 'sticky.'

I have never experienced the hot start problem, and I have never heard the fan come on when cranking either. Might be something in that.
Good mod Greg. :clapping:

Ok.... I just wired this mod.
Remember having some weak starts when hot, so I hope this helps. Seems smart anyway. Thx a ton!!!