carbon on plugs

[film495]

68 evinrude 3hp, decarbed motor and cleaned carb - ran for a couple hours and took a look at the new plugs and they appeared to have some carbon build up around the base of the plug. Is that normal or am I making too much carbon? I'm just wondering if I should decarb again - I ran a can of tuner through it, but I'm pretty sure that had not been done in 20 or more years.

 

[Rick.]

Re: carbon on plugs

I doubt your making carbon that fast. I always use an old set of plugs for the decarb. After it's over then I put new plugs in. Perhaps the carbon is just stuck to your plugs from doing the decarb.? You will see a little form on the plugs over time for sure. How's it running. Are there any issues with the performance or are you just being careful? Rick.

 

[film495]

Re: carbon on plugs

I'm just trying to get it all tuned up this year. It was time to retire it for a new motor or get it tuned up and working good -and it seems to still have a few quirks, it will just quit once in a while still, but starts again on one pull; also, the bottom cylinder seems to flutter from time to time and has flooded out and quit completely a few times also. Saw the carbon on the "new" plugs (no more than 2 or 3 hours of use, new after the can of tuner went through) and made me wonder if my one can of engine tuner may not have been adequate for 40 years of carbon build up. Maybe I'm answering my own question there.

 

[Rick.]

Re: carbon on plugs

I got a new to me 71 - 4Hp last fall. It would run for 10 -15 min. and stop, one pull and the cycle would continue. I cleaned the carb. and put a kit in it and that solved the problem. Now it runs for ever without issue. Not sure how you know the bottom cyl. flutters every once and a while. Could it be that your motor sneezes? A sneeze is like someone turned off the ignition for a millisecond and then back on. It is a symptom of the slow speed knob needing to be turned a wee bit richer. Good luck. Rick.

 

[tashasdaddy]

Re: carbon on plugs

also open you plug gap to .035 will help with the carbon build up. if you troll alot you can open it to .040.

 

[film495]

Re: carbon on plugs

also open you plug gap to .035 will help with the carbon build up. if you troll alot you can open it to .040.

Oh - that's interesting. I'll certainly add that to my bag of tricks.

 

[film495]

Re: carbon on plugs

I ran some Sea Foam through it yesterday (the tuner type you spray up into the carb air intake) with some older plugs and it seemed to run better after the procedure. It still does just die once in a while, but it does just start again with one easy pull. Maybe that is a coil starting to friek out once it is pretty hot? I bet the carbon on the plugs is because there was still a bunch of carbon in there that did not come out on the 1st decarb. I'll run it for a while and take a look at these plugs and see if they do it again.

I'm working under the assumption the lower cylinder has an issue because I have had it just flood out a few times and completely stop firing (I isolated that cylinder by checking the temp and the top one was hot and the bottom not). And based on the carb low speed setting, it appears to skip on that cylinder sometimes - but, not completely quit and flood out. It seems that if I open the slow speed adjust on the carb a little more, the rpm on the slow setting drops a little, but I do not get the flutter - or skipping on the bottom cylinder. The best low rpm is almost closing that needle right out where it is only 1/4 turn from seated - and I wonder if I'd be better off to just leave it at the 1.5 turns open, and run at the default setting there. That danged low speed setting has always confused me.

And thanks for all the tips on this motor - a big thanks - still a little tuning to do with this thing, but really - running better than I ever imagined already and I feel like just a little more work and I'll have this thing all figured out.