Idling fouls plug...UPDATE

Well,I checked out my Motomarina last night `til about 11 P.M..I thought about everything you guys said and did this:(1) Ron said drain the gas and I did.Replaced with a whole tank of fresh(almost 3 gallons).No change in the problem.So to the carb.I go.(2)Completely cleaned carb and air filter(there was a little oil in airbox)and reset float `cause it seemed a little high.It's non-adjustable so I shimmed under the needle valve by cutting the proper thickness from an old feeler gauge and tightly wedging it into the plastic float.I've done this before and it really works great.STILL SAME PROBLEM.(3)Also verified that the float and needle valve are not leaking thru.(4)Checked choke and idle setting per Rick and Miguel but no problem there.(5) So now I'm down to Doug and Ron's advice on stuck rings or cracked or not having enough spark.I lost my compression tester so I'll check the spark tonight............There's only one outside shot that I hadn't mentioned because the bike ran for days with no problem after I did it,but I did port the intake pipe a while back because of a restriction in the 90 degree turn.The only way that could be the problem is if(which I doubt) I didn't idle the bike for an extended time during all those days and long trips.Any more advice is appreciated.THANKS!

Re: Idling fouls plug...UPDATE

Ron Brown /

Don,

I have never seen your ped so I do not know what kind of carb you have so kust use what you can.

If you can take off the choke and idle very soon after starting from cold then you are running too rich. If not, the problem lies elswhere, weak spark or wrong plug maybe. I dont have much faith in the bad rings/compression theory, after all, the same stuff is above the piston as below it so who cares, if it has enough compression to run well.

If you are too rich, if your carb has an idle mixture adjustment screw, turn it toward lean. If your carb has a needle in the slide, lower it a notch, even though it is not supposed to affect idle. If your carb uses an enrichment device instead of a plate that restricts the intake, take it apart and check that the "rubber" tip is in good shape and the seat is clean. If all of this checks out, it sounds like too big an idle jet, is this replaceable in your carb?

Ron

Re: Idling fouls plug...UPDATE

Thanks,Ron! I should've mentioned that it's a super simple carb with NO adjustments other than idling screw lifting the throttle slide.The choke is only needed for 15-20 secs. ,but that's the way all my bikes are.I think you are putting me on the right track when you say it's spark.I will check that tonight.These carbs(Dellorto)are so simple they're amazing! All my life I've worked on adjusting carbs.and rebuilding 2Vs,4Vs,single-throated,dual quads,etc.and to see how well these are made is a new experience.I don't mean I'm an expert on carbs.,I mainly just did grunt work for chief mechanics.I could stand to learn a lot more about flow and atomization and the like.I'll keep you posted on the results,`cause I'm determined to get this fixed.It's my main traveling `ped because it has the 2 gears.But I've got the Sebring with the Minarelli on standby if I need it.

Re: Idling fouls plug...UPDATE

Hi Don, I will stand on rings, final answer (ha!) Let us know who wins the golden nut award... Doug

Re: Idling fouls plug...UPDATE

Okay,Doug! I'll answer honestly.But I'm leaning Ron's way because of the suddenness of the problem.That's why I suspected the mixed brands of oil at the first.The `Golden Nut Award' ;not bad..............if we lose do we get just a `regular nut' award? (8^)

Re: Idling fouls plug...UPDATE

Ron Brown /

Don,

If you cleaned this carb, did you poke anything through the pasages in the carb body? If your carb is typical, one of these pasages is an idle jet, drilled into the aluminum or pot metal carb body and is really easy to open up a bit.

Ron

Re: Idling fouls plug...UPDATE

Yeah,Ron,all passages are clear to the best of my knowledge.I always check them before assembly by blowing carb cleaner thru them by using the spray tube that comes with the cleaner.But if a passage was plugged,why would it idle so well?It'll sit there for a long time just idling away,but as soon as you get on it to go,Sputter and die immediately.Of course while it's idling the plug is getting sootier too.Weird,huh?

Re: Idling fouls plug...UPDATE

Oh! I just got what you're saying I think,Ron.You mean did I inadvertently enlarge a passage? No,I don't use anything unless I'm SURE the spray won't blow it out.When I do,I use only very fine copper wire taken from a finely stranded piece of wiring.

Re: Idling fouls plug...UPDATE

Ron Brown /

Don,

Glad you re-read my post, thought I would have to have you self administer a "dope slap". : )

Back to the spark, idling fouls the plug somewhat, which it almost always does on a 2 cycle because it actually 6 or 8 cycles at idle. When you open the throttle to take off, the increased mixture density in the cylinder makes it even harder to spark across the plug and so it fouls out.

If this is true, narrowing the plug gap should improve it.

Ron

Re: Idling fouls plug...UPDATE

Keeettchhh! Did you hear that Ron! I gave myself a `dope slap' just for good measure.Well,on that gap thing:I know it's only gapped at .024" now.It's a new plug.How much narrower would you gap it? You know,I can't check it `til 7:30 P.M.,but you got me wantin' to `dope slap' that spark plug right now! I can't wait to get home and do it.I didn't mention this earlier,but trying out the `ped last night I got to go on a pretty long ride in excellent weather,although dark.

Re: Idling fouls plug...UPDATE

Ron Brown /

Don,

I don't know exactly, but you are just trying this to determine if a weak spark is likely to be the problem, so I would try about .016 or so and see if the symptoms change.

Ron

Re: Idling fouls plug...UPDATE

Okay,Ron! Sounds like good advice as always! I'll try that right off the bat.THANKS!I guess I can always carry around a wire brush and a dozen spark plugs with me if I don't solve it.Ha!

« Go to Topic — end of thread

Want to post in this forum? We'd love to have you join the discussion, but first:

Login or Create Account