rich or lean?

[xnicklopezx]

Hey guys, I have a little problem, my bike ever since putting the muffler on correctly has been all whacked out. It was running rich, however, i bought a smaller jet hoping to make it leaner. I'm not quite sure if it worked, i mean it rides around 2mph faster...but the plug itself is a NGK B6HS and the color of the ceramic is very light tan and every bit of metal though is like charcoal black around the top of the threads and the metal that hangs over the electrode. SO, the light ceramic makes me think its lean...(ive read people saying that this is the only part u read) but there is also the black making it possibly rich? (ive also read people saying to read the general color of the spark plug toward the top) Any help is appreciated. More info, its an NT carb, skyhawk 48cc gt2b engine, and i went from the stock jet (.70mm i believe) to one size smaller (.68mm) and i also have one size smaller a .66mm that i will try tomorrow, any tips?

 

[GearNut]

The color of the ceramic is what you want to look at.
The rest of the spark plug innards typically will be black or dark grey.

Edit: you are currently running too lean. You need to tune/ jet it for more fuel.

 

[rustycase]

You didn't mention what kind of mix oil you are using, or the ratio...

Better to try your testing to richer... and see abt improvement than go too lean and burn a hole in the piston !

I was once told, that with our e85 alcohol laced fuel here in Glorious Kalifornia that a healthy engine will now stray from the perfect light tan towards the dark side, because of that alcohol... makes sense to me, if the state was involved in something.
Good luck
rc

 

[GearNut]

My spark plug is burning California's glorious E85 and Maxima 927 oil. It is a nice dark grey.
Perfect color taking into account the the additives in the Maxima 927.

 

[xnicklopezx]

im using lucas oil, 50:1 (thats what the bottle says...) this is my first tank at 50:1 usually was doing 25:1, maybe add more oil, go for like 32:1? plus im having much more problems now, the engine died while riding and even with the clutch in became very hard to pedal and is a pain in my ass, im tearing it up now to figure it out, its not a ceased piston, maybe a bearing or something, ill let u know

 

[GearNut]

After the break in is done, you will be fine running anywhere from 32:1 to 50:1. Just be sure to re-tune the carburetor for the mixture of your choice as the pre-mix oil makes the fuel physically heavier. The more the oil the less flow through the carburetor's fuel passages. Less oil lets more fuel flow through the same passages.
If you changed from 25:1 to 50:1 without a re-tune then you would be running rich assuming that you originally had it tuned properly for 25:1 before the switch.

 

[xnicklopezx]

cool, thanks guys, honestly right now im dealing with a busted bearing in the rear tire which i think had something to play in the bike not working so well, but i do believe i was running a little rich, once everything is fixed on the bike not engine, i will be fine tuning, finally starting to get the hang of these darn things, although i dont wanna say that too soon seeing as every time i do, i have to learn something new cuz something new breaks lol. a little history on the bike, it was at 25:1 and was running beautifully, until i realized the muffler gasket was blown to bits...so no biggie i figured, i put in a spare the kit came with and got that all working good, and it decreased my speed by 10mph...kinda sucked seemed like it messed with a lot of stuff, been tinkering with the engine ever since, the longest ive got out of this engine without breaking down is maybe 3days...what its been through: busted chains, flat tires, water in the magneto case, gear screws coming off, stock carburetor was junk (got an NT now), busted throttle, busted clutch cable, and now broken bearing in the hub....AHHH, i did check piston there was no damage, everything seems to have held up through the chaos, but i just cant wait for it to end......ANYWAYS, thanks for all ur help guys...im sure ill be back with another problem shortlly lol *knock on wood*