Fouled plugs! (again)

[ndutton]

Do you guys realize except for Bingy's question this is a three year old thread?

[JOHN COOKSON]

[QUOTE=Sony2000;72635Idle RPM screw should be backed off, so as to NOT touch the carb.
Run the engine and back off the idle mixture screw until just before the engine starts missing.
Your excess carbon is no longer.
Now, maybe, set idle RPM screw.[/QUOTE]

+1 on this.
I did this same procedure 2 or 3 years ago. It reduced my plug fouling by 1/2 to 2/3.
BTW: I like Bingy have had good luck with Champion spark plugs.

TRUE GRIT

[toddster]

Do you guys realize except for Bingy's question this is a three year old thread?

That's OK. Some of us lurkers are still chasing the same thing.

[Bingy]

Engine started to stumble again last night.
Assuming changing plugs was not the solution.Carb may be set too rich.
Back to boat this morning to check plug condition, check idle adjustment , check wires and check choke.
Engine has received only short runs to race start ,10 min. or less.

Doing another race requiring two hour motor to Lake this weekend.

Will carry spare plugs on board in case problem not solved.

[Sony2000]

#4 in after these changes: suggests you should do it again, but try this....
Idle RPM screw should be backed off, so as to NOT touch the carb.
Run the engine and back off the idle mixture screw until just before the engine starts missing.
Your excess carbon is no longer.
Now, maybe, set idle RPM screw.

Bingy, I'm 4 turns out on the idle mixture screw, to get rid of an excess carbon situation, not as bad as yours. At 4 turns I haven't reached the "missing" point! Yesterday I had to further back off the idle screw, to take the engine down to 600 rpm, and it goes into the upper 500s when in gear.

[Mo]

Engine started to stumble again last night.
Assuming changing plugs was not the solution.Carb may be set too rich.
Back to boat this morning to check plug condition, check idle adjustment , check wires and check choke.
Engine has received only short runs to race start ,10 min. or less.

Doing another race requiring two hour motor to Lake this weekend.

Will carry spare plugs on board in case problem not solved.

Bingy,

Hard to say what's going on there without a pic. If you can get some pics of those plugs when fouled may be very beneficial. I motored 5 hrs again last Friday and decided to pull the plugs Saturday morning for a look-see....all good, even 3 and 4. Still using my NGK XR4's and they are on year 3. Another spare set aboard if needed.

If it doesn't look like heavy oil deposit you might want to pull the carb apart and give it a good cleaning. Also remove that mixture screw, clean up point and threads etc so that it performs as it should. I've worked on a few that were full of corrosion.

All the best with that.

[Bingy]

Pulled plugs this morning,one was damaged,replaced all 4 with Champion RJ8C.Adjusted idle jet out to 2 full turns.
In neutral motor will ramp up easily and back to idle with no hesitation.
In forward gear at full throttle 1800 rpm. Cruising rpm 1300 for hull speed.
Planning on doing carb and points/condenser before haulout.
Will update
Thanks again for the help.

[morphios67]

Hi guys, since you change the coil and you have points and condenser, i think you should change the condenser and points and see if your coil is the right one for them, i get the seam problem and get fix when i change my condeser and points...

[JOHN COOKSON]

Anything funky going on inside the distributor cap?
Are the burn marks on the contacts inside the cap uniform?
Maybe one or more spark plugs are not firing all the time.

TRUE GRIT