fouling plugs, why

lately my kitted sebring has been hard to start after a running it. i pulled the plug on two occasions, and it looks kinda fouled. i then installled a new plug, gapped correctly, and she starts on half a kick.

i'm running 4 oz of oil to a gallon of gas, a little rich i know, but i figured it would help with lubrication of the new kit, plus bearings, and all.

could i be fouling out brand new plugs because of the warmer weather now. it never did this before, so that's what i'm guessing.

any, and all advice is appreciated. thanks

Re: fouling plugs, why

plug chops are showing a great chocolate tan color,almost black, but a little wet...... it's running beautiful. real strong. got clocked at around 45mph next to my wifes car.the funny thing is it's not four stroking at all.

as long as it's just running rich, and not any big problems. i kinda figured it was the weather affecting it.

Re: fouling plugs, why

i took apart the carb today, and installed one size smaller of a jet. i went from #64 to a #62.

it ran well, BUT when i did plug chops it showed a a light tan ceramic. kinda scared me., don't wanna ruin the kit at this point, it's running so well.

i figured that is definetly not a good thing, and went back to the #64

i'm still not getting any signs of four stroking, or any loss of tranny fluid, there's no grayish colors on the plug, no signs of anything leaking, or any air leaks..i'm not sure what it could be now. i'm stumped!!!!!

anyone have any other suggestions.

i also went over the whole bike, and tightened everything up, check fluids, tire pressure,adjusted brakes, stocked up my saddle bags, etc.

i wanted to go on a big ride on thursday (maybe 100miles), but i'm hesitate now

i'm just sick of having to change out the plug after restarting it.

once it's running i go all day with no problems.

if i stop to run into the store, or something. i'll come back out, and i have the problem. put a new plug in, and it starts in half a kick.

sorry, almost left's a 1980 motobecane sebring.

Re: fouling plugs, why

Hmmm.....if it's hard to start after stopping, are you making sure it isn't flooding by shutting the petcock? Once my float was leaking thru slowly. If I started the bike within 5 problem....if I waited 15 minutes, the gas had flooded the cyl.

Just a thought. don-ohio (:^)

Re: fouling plugs, why

thanks for the reply don-o. actually my problem seems to be the opposite. if i try to start it after 5 minutes, no go, but i noticed today it started right up from sitting overnight, i went home after a quick ride, and shut it down. after a couple hours, i gave it a try, and she kicked right over. i can't understand's got my head

Re: fouling plugs, why

But?................Factor in whether you closed the petcock or not? But it still could be weakening spark due to a bad condensor or points not making great contact.

Do the spray thing around the intake to check for inleakage too? Could be an air leak, and i've seen `em make plug chops look crazy. You put in new flyside crank seal whern you kitted it,right? don-ohio

Re: fouling plugs, why

i almost always shut off my petcock. i try to make it a habit.

i had the sebring kitted by chris, mwh, so i'm not sure about the crank seal.

i will check for any air leaks tomorrow, thanks don-o.

Re: fouling plugs, why

Well,Chris might have replaced the crank seal,I dunno. The crankseal on a MO2 is best replaced by a MInarelli seal on ther flywheel side. It's at least half-again as heavy. don-ohio

Re: fouling plugs, why

well i got some time today to check for air leaks. i sprayed carb cleaner all around the intake, carb, etc.

there was no change whatsoever in the rpm's.

there's no signs of a leakage at the crank seals, no drips on the ground, or on the engine from sitting overnight......i'm at a loss.

i decided to roll it into my back yard, and douse it with gas, and throw a match.

that will teach that damn sebring to foul plugs on me

Re: fouling plugs, why

Jason Luther /

you go paul!

Re: fouling plugs, why

Jason Luther /

i had 6 month old gas and it kept fouling plugs? could this be your problem? or is your timing a little off? -jason

Re: fouling plugs, why

seriously, i think i have too rich of a mixture.

i was mixing 4oz to a gallon because of the new kit. now with the warmer weather, and all, it's eating spark plugs for breakfast.

the kits finally broken in, so i have dropped the mixture to 3oz.

well see what happens now.

Re: fouling plugs, why

Are you using the Champion #801 plug? That's what it takes.

I never have bad plug chops with that plug,Paul. don-ohio

Re: fouling plugs, why

no, something chris has in stock that i can't remember the name right

i'll try that champion though.....

i put 45 miles on her today, and all went well.maybe the leaner mixture helped out some.

i did notice a rattling/clanking noise all of a sudden at idle. it totally disapears when i give it gas though.

i have to check on that now......the shit never ends, i tell ya. i hope it's not a big tranny problem, or something

Re: fouling plugs, why

I'm really suspecting that magneto,Paul. Can you check it for looseness and hook the induction timing light to it? don-ohio (:^)

Re: fouling plugs, why

are you thinking the magneto is loose??

when you said check it with a timing light, are you thinking the mopeds timing is off, and that's what's causing the plug fouling????

thanks again don-o for all your help.

Re: fouling plugs, why

_did notice a rattling/clanking noise all of a sudden at idle. it totally disapears when i give it gas though._

Please note that I am _not_ a two cycle mechanic, someone will have to verify this, but in a car engine, oil problems, fouled plugs, and 'crappy' idle that eases up at higher speeds can very easily be caused by a failing head gasket.

Re: fouling plugs, why

Yeah,Paul.........I would check the timing and then the mag for looseness. An induction timing light tells the whole story. `Been there.......suffered that!' don (:^D

Re: hey don-ohio

ok don-o. i checked the magneto, and it is tight. i don't have a timing light, but it seems the points are opening well, and at the right time.

it is making a clanking noise at idle, but as soon as i give it some throttle, it's as quiet as a mouse.

i have not lost any top speed or anything. at full throttle it's quiet also. i don't have time to check the gears for problems as i'm on my way out.

i know i have to drain the tranny fluid, and pop open the tranny cover, should i be looking for something obvious???

do you think it could be a problem with the first gear clutches??

it's shifting fine, and the fluids are perfect.

thanks for your help don, i appreciate it tremendously.

Re: hey don-ohio

it is starting up on half a kick, shifts, and runs real well.

Re: hey don-ohio


Re: hey don-ohio

So Paul all it was in the end was a poor mixture of gas/oil?

Im having the same problem with my 1970 motobecane 50v....Eats a spark plug in 200km.

I use synthetic 2stroke oil and high test gas mixture of 250ml oil, for 8liters of gas.

Ive had friends suggest that I use regular oil and ethonal gas.

What do you think?


Re: hey don-ohio

hello greg. that's what it seemed to be. i was running richer because of it being newly kitted, but now that it's broken in iv'e leaned it out some. i went from 4oz to a gallon down to 3oz.

it seemed to have fixed the problem. i have ran about 50 miles or so without it eating plugs. mine were actually fouling out after every 10 miles or so.

Re: hey don-ohio

I'm new to mopeding and 2stroke engines...Ive been doing some research and I think the problem may be the "pilot air screw".

There should be a kind of "plumbers" rubber washer included, right?

I'm taliking about the little brass screw with the numbers on the bottom and holes through the shaft....the screw that fits in the bottom of the carb.

What does that screw do, and how far should it be screwed in? Ive been screwing them all the way in with no rubber washers.



Re: hey don-ohio

I did some more research and I think the little brass screw on the bottom is the "fuel jet" and I need a "diffuser cap" to go with it. Does this sound right?

How does the fuel jet work?

If the fuel jet is screwed all the way in then would that make the fuel/air ratio too rich?


Re: hey don-ohio

Greg, those MBK carbs(Gurtner?) are nice when they work right, I hear. You are getting a dirty,fouled,plug? Not burning one up,right? Could your choke(enrichener plunger) be sticking partway? Or could your airbox be partially blocked or plugged? Also, the points need to be set at around .016",inches,not Millimeters.

Make sure you don't have an air inleakabe also. don-ohio (:^)

Re: hey don-ohio


Re: hey don-ohio

anyway. i just apart the trany case, and found the front/first clutch, i guess it's called., was loose. i mean the nut.

i checked everything over, as best as i know how, and tightened the loose nut back up.put everything back together, filled it up, ans tarted her up......................

quiet as a mouse. i rode it for like 10 miles ot so without a problem.

on the way home, i stopped at a light, and back came the noise.....

back to the drawing board. drained the fluids, took everything apart again, and found the nut was loose again

so look in the manaul, to see if i'm missing anything(partswise), like a lock washer, or something, but it all checks out.

what do you guys think i'm missing here????????????/

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