My 1986 VF500F revival

Ok so I found out the hotwire.is literally just "run" with lights. The fan switch is wired through the ignition switch. Kinda wondered what the other wires did

Put the battery charger on 2A for an hour, then hit the starter and she fired right up.

Looking into AGM battery options. Either the scorpion YT12C or MotoBatt MB12U

On the plus side, all of my wiring connections have been scotchbrited and deoxit soaked now, and I have a more reliable start button/kill switch pod to install.

Edit
Bacon turned out Amazing

Oh!
And I was looking at replacement key switches.. might need help finding one and setting up the wiring in the plug

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MotoBatt makes excellent batteries. I tend to get 6-8 years out of their AGMs, which is nothing to sneeze at.

 

The MotoBatts got good reviews

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When I permanently eliminate the keyed switch, I make the other needed connections with a donor plug, like off of the bad switch.

 

Brand new MotoBatt installed.

Nothing.

Cranks over fine, just a cough here or there. No starting. Pulled #1 plug, wet with fuel so not a carb problem.

So now Im wondering about the spark units..



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Possible. 500 units are pretty damn resilient tho and bad ones usually aren't intermittent like you describe. Starting no problem to not at all? Both units intermittently failing at the same time?

 

how wet with fuel are we talking ? so wet it flooded out real bad or expectedly wet because there is no spark? if its a cough here or there thats suggests you do have some spark

 

Do you need new plugs perhaps? and do you have spark or not?

 

I'd be tempted to pull the tank and hook up a fuel bottle just to eliminate something from the fuel system.

After that - you know it has to be electrical.

But I defer to the more experienced crowd here.....

 

I am running off an aux tank.

Gotta be electrical for sure. It won't even fire with fuel down the intakes

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So maybe I'm looking at the starter clutch? They've been known to crack, but the odd startup and run thing has me stumped.

This battery has 13.0 testing volts. 13v on both power wires at the solenoid.

13v at the red wire at the key switch end of the harness side.

Key off I read 13v on the coil inputs wires from the spark units.

Memory a bit foggy, but I feel like I had a .5v drop at the spark unit wiring to coil.. have to check in a few hours, gotta finish my shift

Also sent a message to a member on V4MB who remade spark units asking for help

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I replaced the rear plugs with the tool I have now. I'd have to pull the radiator to get the fronts, but seeing as she doesn't run lol I probably should


Spark with a inline tester shows yellow spark on front and rear.

I agree weird that both units would fail..

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And I would think if the starter clutch were damaged, I would not have got the odd 2 times it ran fine.

And the starter cranks the engine just fine

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If it's cranking, it's not the starter clutch. If the starter is spinning up and not "grabbing" or engaging the engine, that's a starter clutch. Or if it sounds like you are making smaller gravel out of larger gravel.

 

I figured the starter clutch since it has the triggers for the pulse generators, which would affect both banks of cylinders, but I forgot about the engagement issue would be present.

Chances of coils failing?

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Pulsar coils absolutely do fail, but are nearly always heat related when acting up and usually affect one bank. But certainly not impossible for both to fail. You can do resistance and continuity checks per the SM, but I have found sometimes they can be inconclusive. (i.e. test bad but work fine, or the opposite) But if they are so bad they are failing when cold, you might get some smoking gun readings.

 

Lemme change the front plugs and do a dynamic test of the ignition coils and see what spark looks like.

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Lol. W T F

I just hit the starter with the hotwire installed and she fired right up.

Completely baffled.

I will still be changing the front plugs, but seriously

WTF

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Front plugs changed.

Pretty black.. might be rich on pilot setting or from weak spark?

Had to futz with the kill switch a bit, but got bright blue fat spark at the plugs, and she fired right up.

So still have a newer dortyy switch, but at least the plugs are new and she fires up.

Charging 14.2x volts at idle.

On with the show and the many other repairs.. keeping an eye on spark still

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Congratulations! Always nice to get some resolution to a problem!