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Author Topic: VF500 Starting Issue  (Read 403 times)

Offline irk miller

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Re: VF500 Starting Issue
« Reply #10 on: Jul 13, 2017, 17:52:22 »
That's where I'd start based on what you described by your spark.  If I understand correctly, you're also getting fuel. 

Offline HiroProtagonist

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Re: VF500 Starting Issue
« Reply #11 on: Jul 13, 2017, 18:33:22 »
I believe I am.

I'll check all 4 plugs today first, and see how the spark is.

Offline cxman

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Re: VF500 Starting Issue
« Reply #12 on: Jul 13, 2017, 20:56:08 »
it realy sounds like a cdi igniter box

viffers dont have a typical cdi system so they dont always do the just work or dont

and one side of the ignition does more than the other in it drives the tach as well as something else

it is  also had to test these reliably

give these guys a call they can point you in the right path

http://www.v4spark.com/

1978 CX650 Super Deluxe
1979 XS1100 Special
1980 XS650
1980 cx500  The Beast
1983 GL650 i
1983 cx650 Custom
1973 CB450
1973 cb750
1980 cb750
1981 cb650
1982 cb900 c
1977  gl1000
1976 gl1000 LTD
 1983 GL1100 Nekid
and a bunch of others

Offline HiroProtagonist

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Re: VF500 Starting Issue
« Reply #13 on: Jul 14, 2017, 01:27:15 »
Awesome. I'm trying to decide whether to start with carbs or electronics. I cleaned the carbs so I'm just not sure how much further to go. HOWEVER, leaving it overnight with the carbs drained and the petcock off resulted in it completely not starting at all!

Offline cxman

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Re: VF500 Starting Issue
« Reply #14 on: Jul 14, 2017, 07:43:07 »
run it from a test tank and eliminate the guess work about the tank and vacuum petcock for now
1978 CX650 Super Deluxe
1979 XS1100 Special
1980 XS650
1980 cx500  The Beast
1983 GL650 i
1983 cx650 Custom
1973 CB450
1973 cb750
1980 cb750
1981 cb650
1982 cb900 c
1977  gl1000
1976 gl1000 LTD
 1983 GL1100 Nekid
and a bunch of others

Offline HiroProtagonist

  • Posts: 126
Re: VF500 Starting Issue
« Reply #15 on: Jul 14, 2017, 12:28:11 »
Roger. Am I crazy or is the vacuum switch not in the petcock - I drained the floats with the tank off and fuel still in the line, and the fuel didn't go into the bowls until I turned the bike over

Offline TheCoffeeGuy

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Re: VF500 Starting Issue
« Reply #16 on: Jul 14, 2017, 17:21:03 »
the vacuum switch is in the petcock. Yes.
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

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Re: VF500 Starting Issue
« Reply #17 on: Jul 17, 2017, 13:01:39 »
It was the carbs! The pilot jets were just a tiny bit clogged - still able to see through them, but the hole was a little bit too small. Cleaned those out and it runs! Just need to run some techron through the gas to hopefully wash the rest of it out

Offline ChopperCharles

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    • Modified Motorcycles by Chopper Charles
Re: VF500 Starting Issue
« Reply #18 on: Aug 03, 2017, 12:13:17 »
The 500cc V4 is notorious for the carbs clogging after it's been sitting. There are a LOT of tiny passages in there, and the carbs need to be immaculate on the inside, or you'll run into hesitation, strange running, and performance issues.

First thing you should always do when you're not sure if it's fuel or spark is shoot some ether (starting fluid) down the carb throats and try to start it.  If it catches and starts running, you know you've got decent spark - decent enough to run at least. Saves a lot of headache diagnosing things.

Also, very VERY few motorcycles actually use CDI ignition. (Capacitor-Discharge Ignition). The V4s are TCI - Transistor Controlled Ignition. Basically you have two identical spark boxes on the 500V4. One of them drives the electronic tach. If you have running issues where it feels like two cylinders drop out, check your tachometer. While the bike is running (poorly) does the tach read zero rpm, or alternatively bounce around crazily? If not, swap the spark boxes. Does it do so now? If it does, you've got a bad spark box. (Check the harness, the connector with the extra wire is the one that drives the tach, and now you know which spark box is bad).

I had the VF500C, which is the cruiser version with the same engine. I'm not sure about the F, but the C did not have a rev limiter box. The bigger V4s have two boxes, one with a white connector and one with a red connector. The red connector box has a rev-limiter built in (cuts two cylinders at 12k rpm). They are interchangeable, and you can run the bike with 2 red or 2 white boxes. With 2 white, you won't have a rev-limiter. With 2 red, all 4 cylinders cut out at 12k. Note that the bigger V4s have a 10k redline.

Boxes from different 1st gen V4 bikes will swap in and out without issues. HOWEVER, the advance curve may be slightly different between boxes. You can still do it, but in that case you should replace them in pairs. I didn't notice any performance issues running my V65 Magna (VF1100C) with V30 (VF500C) spark boxes, and I keep a pair as emergency spares in case of a failure on the road. Also, since the larger bikes have a lower redline, you may want to avoid the boxes with red connectors, as they'll cut out sooner. Then again, maybe not:

The 500 V4s have fragile wrist pins. Don't spin them past redline. My first bike was a V30 I got in boxes, because of that issue. Broken wrist pin, scored cylinder wall, but fortunately it broke at idle and the PO shut it down immediately, so a honing fixed it enough to be a runner again.  (It burned a little oil, but I could live with that).

Also, dunno if it makes a difference but the V30 Magna and V30 Interceptor (VF500F) have the exact same motor... but the Magna has 500rpm lower redline. 11,500 on the magna, 12,000 on the Interceptor. There is no difference to engine internals, the only difference is printed on the tach itself. Just keep away from redline if you want your motor to live!

Charles.