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M750 fouling plugs

Started by DownwtheQuickness, April 06, 2013, 06:35:11 PM

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DownwtheQuickness

April 06, 2013, 06:35:11 PM
Smart people,

My bike has curiously fouled two plugs in the last few months in the vertical cylinder only. After the second one, I knew the plug wasn't the only problem. It seems like the mixture has somehow gotten screwed up and it's running too rich on that one side. Both plugs look about equally darkened, yet the horizontal cylinder has never stopped firing, even when the vert is fouled and only occasionally backfiring.
I found the screw to adjust idle speed, but can't find the mixture screws. That seems like the first place to start, but could it possibly be a jet problem? Any help/direction is greatly appreciated!
2000 Monster 750

ducpainter

#1
April 06, 2013, 06:49:17 PM
Could be several things.

How many miles?

Do you still have the vacuum petcock?
"Once you accept that a child on the autistic spectrum experiences the world in
 a completely different way than you, you will be open to understand how that
 perspective
    is even more amazing than yours."
    To realize the value of nine  months:
    Ask a mother who gave birth to a stillborn.
"Don't piss off old people The older we get, the less 'Life in Prison' is a deterrent."


DownwtheQuickness

#2
April 06, 2013, 06:55:53 PM
I'm at about 16k miles, bought it at 12k two years ago.
I honestly don't know what a vacuum petcock is.

I forgot to mention, however, that I DID go through the entire ignition and wiring with a multimeter, and got all the correct impedance, and since the plug sparks when it's new, or switched with the horizontal cylinder's plug, I'm pretty much ruling out an ignition problem.
2000 Monster 750

ducpainter

#3
April 06, 2013, 07:04:04 PM
Quote from: DownwtheQuickness on April 06, 2013, 06:55:53 PM
I'm at about 16k miles, bought it at 12k two years ago.
I honestly don't know what a vacuum petcock is.

I forgot to mention, however, that I DID go through the entire ignition and wiring with a multimeter, and got all the correct impedance, and since the plug sparks when it's new, or switched with the horizontal cylinder's plug, I'm pretty much ruling out an ignition problem.
The vacuum petcock is what shuts off the fuel when the engine isn't running.

The vacuum line from it runs to one of the intake manifolds. It is located under the bracket the tank hinge bolts to.

Three lines...2 large, and one small diameter. Trace the small diameter hose to the intake manifold it goes to. If it's the vertical, pull it and see if it's wet or smells like gas. If it does I'd wager that's your problem.

If it isn't wet it might simply be time for needle jets/emulsion tubes.
"Once you accept that a child on the autistic spectrum experiences the world in
 a completely different way than you, you will be open to understand how that
 perspective
    is even more amazing than yours."
    To realize the value of nine  months:
    Ask a mother who gave birth to a stillborn.
"Don't piss off old people The older we get, the less 'Life in Prison' is a deterrent."


DownwtheQuickness

#4
April 06, 2013, 07:15:24 PM
Found it, traced it. It goes to the horizontal cylinder...
2000 Monster 750

ducpainter

#5
April 06, 2013, 07:25:00 PM
Quote from: DownwtheQuickness on April 06, 2013, 07:15:24 PM
Found it, traced it. It goes to the horizontal cylinder...
Now trace the one from the fuel pump, and see if it goes to the vertical.

Check it for wetness.
"Once you accept that a child on the autistic spectrum experiences the world in
 a completely different way than you, you will be open to understand how that
 perspective
    is even more amazing than yours."
    To realize the value of nine  months:
    Ask a mother who gave birth to a stillborn.
"Don't piss off old people The older we get, the less 'Life in Prison' is a deterrent."


DownwtheQuickness

#6
April 21, 2013, 02:09:52 PM
Sorry it took so long for me to get back to you, the board said I had no replies to my posts. Anyways, I checked it, and it's bone dry (as it should be, right?). I took the carburetor(s) out, long story short [bang], and am waiting for a weekend I can drive in to San Antonio to have the guys at SA Ducati take a look at it. I've heard good things about their service, so I'm pretty optimistic.
Anything else you guys can come up with, I'm more than happy to attempt! Thanks for the knowledge thus far.  [beer]
2000 Monster 750
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