Spark plug soaked in fuel, stuck slider?

[VmaxVboost]

I have a 2000 Max with 73,000 miles on it, stock carbs, jets, and exhaust.

For the last 4 months, it has been running as if one or two cylinders are not firing.

At a red light, the idle will switch from perfect to a stutter (like a Harley), then back to perfect, within the same red light. At any given red light, you are not sure if you'll get a good or bad idle. At highway speeds, all of a sudden, the faulty cylinder will "correct" itself, and the Max will have a significant increase in smoothness and power, so the problem occurs at idle or highway speeds.

I have done a very thorough electrical check (replaced two bad coils, and two bad spark plug wires), and have now verified that all four cylinders are getting spark. I have swapped out the igniter box (thanks to Morley), with no change.

The throttle side rear plug is soaked in fuel, while the other three look normal. I have brand new NGK plugs in all four cylinders.

Any help? Use Seafoam?

Brian
San Diego, CA

 

[93max]

Is the wet plug in questions coil been replaced? Possible bad connection at the plug boot or the boot is going bad?

 

[VmaxVboost]

Yes, the wet plug's coil has been replaced.

I used a "Lisle 20610 Inline Spark Tester", bought from Amazon, and verified all four cylinders are getting voltage to the plugs. The tester is in series, in between the boot and the plug.

After repeated boot disconnections and reinstallations, no change.

Thanks, 93max

Brian

 

[93max]

Yes, the wet plug's coil has been replaced.

I used a "Lisle 20610 Inline Spark Tester", bought from Amazon, and verified all four cylinders are getting voltage to the plugs. The tester is in series, in between the boot and the plug.

After repeated boot disconnections and reinstallations, no change.

Thanks, 93max

Brian

I'll try to find a pic of my sons cb750 had a very similar issue. it would break up sputter until upper rpms. turns out it was missing part of the needle jet the protrudes into the carb.
He dropped it off to a "professional" and he couldn't find it.
So my son went through the carbs for the 100th time and there it was!
1st pic it's missing by needle, 2nd presto!:biglaugh:

 

[dannymax]

Doubt that it's a stuck slide. More likely to be a stuck needle or float.

 

[VmaxVboost]

Thanks dannymax

What is the best fix for stuck needle or float?

Seafoam?
Remove carbs from bike, and clean in "machine shop parts cleaner"?
Purchase rebuild kit for all four carbs, and make them like new?

Brian

 

[Fire-medic]

A thorough cleaning (carb soak) disassembled, of the carbs seems like it's in-order, and new float valves/seats, and the bowl chamber o-ring gasket. Set the float level dry, and check it wet. Synch the carbs after you know the floats are set correctly. I expect that should do it.

 

[VmaxVboost]

Fire-medic, I agree, specially on an 18 year old bike with 73,000 miles. I guess I was waiting for someone to tell me what to do.

 

[[email protected]]

If you can get it to idle poorly in your driveway, I'd shut the bike off and drain the float bowls. Compare the amount of fuel that comes out of the carb with the wet plug to the others. In other words, use a graduated container or, mark your container.

If the carb that feeds the wet plug has more fuel in the bowl than the others, you just confirmed a float issue with minimal effort.

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[93max]

If you can get it to idle poorly in your driveway, I'd shut the bike off and drain the float bowls. Compare the amount of fuel that comes out of the carb with the wet plug to the others. In other words, use a graduated container or, mark your container.

If the carb that feeds the wet plug has more fuel in the bowl than the others, you just confirmed a float issue with minimal effort.

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This is a great idea but wont the one that is leaking be the same as its going to seek it's own level or do I have it wrong?
Won't the pump keep running also with key on/engine off if the float is stuck or too high?

 

[rebeltaz83]

I bought my 97 with a stick float, has would pour out of the vent hose at the top of the air box. Still ran, just leaked gas. I drained the float bowls and pulled the fuel line off and sprayed carb cleaner directly into the carb got rid the trash stopping the needle from seating and cutting off the fuel flow. Quick fix, ran half a can of sea foam every tank for about three months. ( it sat for 2 years because the owner didn't want and didn't have time to mess with the carbs) that was in April of 13 just rebuilt them last year. carbs were spotless when I tore them down, had a stuck needle in the #1 carb (left rear sitting on bike). Shut bike off pulled faux tank cover to of air box and you could see gas flowing post the needle in the throat, it would drain the bowl into that cylinder. Had same conditions as you, wide open ran like a banshee, idle or cruising it would stutter, buck, pop, backfire, like riding a bull. Found by hearing a sizzling sound when I shut it off.......... Pulled the slide cover needle and slide spring drained the float bowl left the drain open sprayed carb cleaner in, gently blew compressed air. Turned on key with bowl drain open flushed it closed drain. Put it back together, been running fine since.

 

[vmaxed1989]

Thanks dannymax

What is the best fix for stuck needle or float?

Seafoam?
Remove carbs from bike, and clean in "machine shop parts cleaner"?
Purchase rebuild kit for all four carbs, and make them like new?

Brian

My Vmax when hot would run erratic on tick over often stalling when waiting at stop lights. I pumped carb cleaner into the carbs with air filter off and also cleaned the float chamber with brasso and now okay but several applications of carb cleaner


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[[email protected]]

This is a great idea but wont the one that is leaking be the same as its going to seek it's own level?

If the float is stuck, the float chamber will have more fuel in it than the others.

Won't the pump keep running also with key on/engine off if the float is stuck or too high?

Key off engine off.

 

[VmaxVboost]

Thanks for your input. I've decided to have dannymax rebuild the whole carb set.

I have a long history of carb problems with this bike, and would love to have the problems solved for the next XX years.

Brian

 

[Traumahawk]

I had Danny rebuild my carbs several years back. Some of the best money that Ive spent.

 

[D-Max2012]

I have a long history of carb problems with this bike, and would love to have the problems solved for the next XX years.

Just from personal experience, AND if you have not done so already..
COAT YOUR TANK!!!
Kill the problem at the source.

It sucks when you pull the carbs and clean the hell out of them, only to have the same crap show up a few weeks or months later.

I did my used 91.
Even though the process was a lot of work and slow,,, I should have tackled it 1st.
It would have saved me a lot of time, money, and sweat.

While I waited a full week, for the coating to cure.
I took the time to pull out the pump and disassembled it, cleaned and rebuilt it.
Pulled the carbs, completely broke down and ultra-sonic cleaned.
Pulled all fuel lines to clean them all on the bench.

So far, 5 years - Crystal clear fuel system, and counting.

Good luck, Take care.