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Author Topic: VF500 Starting Issue  (Read 684 times)

Offline HiroProtagonist

  • Posts: 143
VF500 Starting Issue
« on: Jul 12, 2017, 14:24:45 »
Hey all,

Just got a VF500 and I'm having the oddest issue. The bike turns over fine, gets a solid spark (red not blue, but solid all the same) and will turn over once, but then not turn over again until I let it sit for quite a while (30 minutes plus).

I cleaned the carbs and they were pristine from the moment I opened them. I would assume that the engine is flooding but this seems extreme.

Here's a video of the issue


Offline TheCoffeeGuy

  • Posts: 608
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Re: VF500 Starting Issue
« Reply #1 on: Jul 13, 2017, 09:31:40 »
leave the petcock off and try it.  on the other hand if there is a vacumn tube that opens the fuel flow, it may not be connected.  this will not allow the fuel to flow at all.   So the once over is basically fuel vaporizing up into the carbs from the bowls giving you the one fire.   Wait 30 and more vaporizes to give one more fire.

JMO
www.thecoffeeguy.ca Not your ordinary Blog site.

1968 Harley Aermacchi ML 125 Rapido, restored
1972 Honda Cl 450 engine rebuild, a day rider soon, now sold
1980 Suzuki GS850GL Street Brat  My other day bike
2000 Harley 1200 Sport S My day bike
1982 Honda CB650 Chopper light

Offline irk miller

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Re: VF500 Starting Issue
« Reply #2 on: Jul 13, 2017, 09:45:31 »
A red spark is a very weak spark. Red is the coolest color, then to orange, yellow, blue, white.  Not sure if you'll get ignition at that compression.  I'd run through the ignition and test those coils.  They may be overheating or something and on their way out.

Offline HiroProtagonist

  • Posts: 143
Re: VF500 Starting Issue
« Reply #3 on: Jul 13, 2017, 13:20:12 »
Good god I love you guys. Posted on the VFR forum and nobody is any help at all.

Offline HiroProtagonist

  • Posts: 143
Re: VF500 Starting Issue
« Reply #4 on: Jul 13, 2017, 13:32:49 »
SO:
I took off the air box and fired it up. I was seeing the slides bob up and down and seeing what appeared to be fuel coming up the jets near the needles, so I'm prettttyyyy sure it's getting fuel.

Would the vacuum tube issue stop fuel from coming up the jets or just stop it from getting to the float bowls?

My next steps that I've thought of:
  • To eliminate it being a flooding issue, I have drained the floats completely, and left the petcock off. I'm going to turn it on for a very short amount of time (just enough to get some fuel in each bowl) and try to fire it.
  • Once I do that, I'm going to turn it on and fill up the bowls. Then I'll open the drains and make sure each bowl has gas. (Should not be that, though, as I know that at least 3 of them had gas, so at least 3 of them should be firing.
  • Check all 4 spark plugs to see if they're getting weak spark. I check a front one yesterday with the actual plugs intended for the bike (I was testing before with a spare plug because taking these plugs out is the worst thing ever) and it had a nice white spark

Any advice on the next steps after this? From what I understand I should have eliminated flooding, made sure fuel is getting to the carbs, and spark. Guess I just have to clean the carbs again? Maybe check the diaphragms?

Offline TheCoffeeGuy

  • Posts: 608
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Re: VF500 Starting Issue
« Reply #5 on: Jul 13, 2017, 15:23:55 »
the vacuum tube from the petcock would stop fuel from getting to the bowls
www.thecoffeeguy.ca Not your ordinary Blog site.

1968 Harley Aermacchi ML 125 Rapido, restored
1972 Honda Cl 450 engine rebuild, a day rider soon, now sold
1980 Suzuki GS850GL Street Brat  My other day bike
2000 Harley 1200 Sport S My day bike
1982 Honda CB650 Chopper light

Offline HiroProtagonist

  • Posts: 143
Re: VF500 Starting Issue
« Reply #6 on: Jul 13, 2017, 15:26:15 »
Rgr. That should be easy to test.

Offline HiroProtagonist

  • Posts: 143
Re: VF500 Starting Issue
« Reply #7 on: Jul 13, 2017, 15:41:34 »
Also heard that it could be CDI related. Any input on testing that?

Offline irk miller

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Re: VF500 Starting Issue
« Reply #8 on: Jul 13, 2017, 16:17:06 »
Start at your plugs and work your back to test for resistance. Check the plug connector to the positive connector on the coil, and check the positive to negative connector on the coil.  If you have resistor caps on your plug wires, check with and without the caps. As far as the CDI, I'm pretty sure they work or they don't.   

Offline HiroProtagonist

  • Posts: 143
Re: VF500 Starting Issue
« Reply #9 on: Jul 13, 2017, 17:12:25 »
Start at your plugs and work your back to test for resistance. Check the plug connector to the positive connector on the coil, and check the positive to negative connector on the coil.  If you have resistor caps on your plug wires, check with and without the caps. As far as the CDI, I'm pretty sure they work or they don't.   

Judging by this you believe it's electrical?