White spark plug tip

Chilly · Post by **Chilly** » Sat Jan 21, 2012 7:17 pm

Replaced my spark plug after 10k miles, the tip is fairly white. So I'm running lean I suppose. Scooter is running fine, does have a rare backfire when I came to a coasting stop(once a week or 2 only-I ride 200 miles a week). Smooth idle, gas milage good, top speed consistent. No modifacations Is this something I should be concerned with?

Lotrat · Post by **Lotrat** » Sat Jan 21, 2012 7:40 pm

White is not good. You are probably just running lean which will cause your motor to run hot. Not good. The backfire may just be an exhaust leak. Both need to be resolved.

Chilly · Post by **Chilly** » Sun Jan 22, 2012 2:27 am

No exhaust leak. Took the plug indoors, it looked whiter in the sun. The very end tip actually is brown, around the base of the tip it is 60% brown, 40% white off white. So I guess slightly lean. Where should I look first? Clean the jets?

Lotrat · Post by **Lotrat** » Sun Jan 22, 2012 3:36 pm

These are what your plug should look like. Moca brown is the color. Some grey is ok, but since you are also have a back fire condition and confirmed you don't have an exhaust leak then you are probably running lean. Running lean on a 2 stroke is bad since the oil your engine needs for lubrication is in the gas. The mixture adjustment is done with a special D shaped tool. It's not complicated to do, but you need to be able to watch RPMs as you do it. If you don' t have all the tools, I'd just bring it in for a carb adjustment. Since you have the plug out, bring it by your scooter shop and ask them what they think.

Chilly · Post by **Chilly** » Sun Jan 22, 2012 10:30 pm

Thanks a lot for your answers. It's a 4 stroke. Just rechecked my valve clearence(perfect) and checked new spark plug(has 600 miles) new plug is pretty much evenly grey/dark grey, not so much brown but no white really. The backfire is rare(like once every 300 miles maybe) and always as I coast to a stop. Does the 4 stroke(buddy 125) have an adjustment screw(fuel/air) also? I'd much prefer to buy the proper tools and learn as I go than go to the shop. I also went through the whole scoot looking for anything loose/leaks ect... all looks solid, buddy runs great otherwise. Seems like she is running just a touch lean? Perhaps just adjust the air/fuel just a touch if this is possible? I was going to clean the carb next but maybe air/fuel adjustment is better way to go first?

Lotrat · Post by **Lotrat** » Tue Jan 24, 2012 3:19 pm

No idea why I thought your was a 2 stroke. Guess my age is showing.

There are lots of 4 stroke spark plug charts out there for you to compare yours to. Yes your carb has a mixture screw. Id turn it out an 1/8 of a turn and see how the plug looks next time. It's better to be a tad rich than a tad lean.

Chilly · Post by **Chilly** » Wed Jan 25, 2012 12:04 am

That's my plan then, will turn the air/fuel screw 1/8 a turn counterclockwise and check plug after a week(200 miles). The screw is brass and on the left side of the carb, yes? I'll open it up this weekend and see if I can find it. Thanks again for your help.

Chilly · Post by **Chilly** » Mon Jan 30, 2012 11:38 pm

Turned it 1/8 a turn counter-clockwise, only put 50 miles on it so far so haven't yet re-checked the plug BUT the ride has completely smoothed out upon starting (0-5mph). The ride was always a bit choppy in the 0-5 range-moreso lately and I had always assumed it was a transmission issue, I had even switched out the belt and rollers because of this. When that didn't help much I opened up the transmission again to make sure all was well. Finally just decided it was a little rough at first, not really a big deal. But now smooth as pie! Will check the plug this Sat. but very happy with the results so far. Thanks again for help Lotrat.

lorenajack · Post by **lorenajack** » Fri Feb 03, 2012 7:41 pm

The spark plug in my 2005 Stella 2T gets fouled at around 400 miles.
When I pull it out it's totally covered in black soot.

Maybe I don't wind it out enough in all 4 gears? However, I would rather
run it on the rich side than too lean and burn up the engine.

You guys have any suggestions?? Thanks!!

Lotrat · Post by **Lotrat** » Sat Feb 04, 2012 4:06 pm

lorenajack wrote:The spark plug in my 2005 Stella 2T gets fouled at around 400 miles.
When I pull it out it's totally covered in black soot.

Maybe I don't wind it out enough in all 4 gears? However, I would rather
run it on the rich side than too lean and burn up the engine.

You guys have any suggestions?? Thanks!!

Two strokes will soot up, that's the nature of the beast. Your choice in 2T oil and how far you ride will also effect how you read your spark plug. Short easy going trips will leave you with a sooty plug. If you lean out the carb trying to correct it when it's really your riding style would be bad. First big hill you come to you'll notice a lack of power and the lean mix with less oil could damage your motor. What kind of MPG are you seeing? How's it run?

lorenajack · Post by **lorenajack** » Tue Feb 07, 2012 9:58 pm

I would rather run a little rich than too lean and damage the engine.
My daily trip is 12 miles each way, mostly on a long busy street
where I have it cranked up to max RPMs.
When I turn a corner I typically run in 3rd gear. I could use 2nd
which would increase the RPMs. I guess it's all a matter of how
much gas I use. I get around 60 MPG.

Chilly · Post by **Chilly** » Sun Feb 12, 2012 2:17 am

So after a few checks of the plug I have ended up turning the mixture screw 3/8 a turn counter-clockwise(richer). The scoot runs better than ever and plug tip is a nice mocha brown. Hopefully running lean all this time didn't put to much a strain on the engine.