Could someone smart tell me whats going on?

[dank]

while i was changing clutch oil and my filter last night, i decided to check my spark plug. it still sparks fine, but its black and looks to have some carbon build up. is this a problem? and if so, caused by what? the way i understand it it should be a light golden brown color.
im running yamalube 2r at 40:1, and i haven't the slightest clue as to what i have for jetting. any help would be great!
Thanks
dan

[HuskyDude]

Well before your get into it your are going to have to find out what jets you have.
Time to get into the carb and see. If this is you first time lay things out in the order you take them apart. It will make it a lot easier when it comes to assembly.
Maybe even draw yourself a couple of pictures. ( having someone that has been into a carb before and to show you things wouldn't be a bad Idea.)

[jostby]

How long have you rode it with that plug? Also, how does the bike run? If you aren't fouling plugs and the bike runs fine I'm not sure I would mess with it.
Also, the last time you rode, was it slow or a long downhill or off throttle before you stopped the bike? That could make the plug look that way. You may also be running a colder plug than specified? I'd check that also.

The correct way to check the plug and jetting is a "throttle chop". Bike is at operating temperature, find a long straightaway and about the time you get 1/2 way through 5th or 6th gear pull the clutch in and kill the bike with the kill switch. Now is when you want to check the plug.

[dank]

0.0
im not even entirely sure i have a place to do that, and it sounds absolutely terrifying.
i mostly ride way down in the rpm (new rider, lots of riding on the clutch in the woods, almost never rev it high.) so that probably has alot to do with it. i bought it with this plug in it, and its never fouled out, so as long as its going to keep working then i suppose i wont worry about it. i think the plug is correct, but im not sure.

[jiauka]

A pict of the spark plug will help a lot, our bikes MUST be reved hi every noe and then in order to clean carbon deposits at the plug, PV and exhaust.

Your bike may be a litle rich or the plug is too old, time to change it, running rich won't harm it, but it is better to jet it correctly.

have fun,

j.

[dank]

i do rev it to clean it out, i just dont ride real high in the rpms. and it seems to run fine, good enough for what i need it to do anyhow.

[roostafish]

I'm going to step out on a limb with an answer here.
1. Change the plug. My policy is if I pull a plug out, and it's not to take a reading for jetting, or I forgot when it last was replaced, a new one goes in. So with that, replace the plug. A cheap BR8ES is just fine. A B8ES is fine too. Don't waste your time with an expensive fancy electrode. Just my opinion.

2. Check your air screw setting. On the left side of the bike, looking at the carb, there's a little brass screw inset at the back, left side of the carb, behind the slide and above the float bowl. Carefully screw it in all the way 'till it lightly seats, counting your turns. It may even pay to dab a bit of paint on a small part of the screw and carb to make sure you get the turns right. If you are 1 1/2 turns out from fully seated, it's probably pretty close, but take note of where that is because this setting is crucial to the way your bike runs at small throttle openings.

3. Without ever having to pull the carb or float bowl you can take the top off the carb. From your description of how you ride, and the color of the plug I'd lean out the needle one clip position and see how you like how it runs. A needle change will be the most dramatic thing you can do as far as the way the bike feels anyway.
To do this, loosen the clamps on either side of the carb and spin the top out towards you. Unscrew the cap and pull the whole thing out. Attached to your cap is a spring, the slide, containing the cable and needle. Compress the spring, push the cable in toward the bottom of the slide and remove it by unseating it from it's position and slipping it out of the slot in the keeper. Next take a 6mm socket and remove the keeper for the needle. Look at the needle and take note of where the clip is. The position on the bottom is richest, the position on the top is leanest. Wherever it is (likely in the center), carefully remove it with a pair of pliers, straight out the side (hold the clip with pliers, then push the needle out for best results, not losing the clip is important) and move it up one position, thus leaning your mix out.

4. If you like the results of that, you may want to remove the carb and pull the jets out (we can discuss that in another post) and see what size they are. Likely the pilot is a 42ish, and likely the main is a 175ish. For your style of riding, I wouldn't even worry about changing the main, it just won't matter too much.

[dank]

actually, i was out riding today, and with the new clutch oil and a clean filter, it ran like a champ, and i could bog it way down low and she still wouldnt kill. so as long as i dont start fouling out plugs on a regular basis i might just leave it like it is. however, on a side note, that last description you gave has been the most insightful description of how the different jets and needles and such are layed out. so thank you for that. before that i had absolutely no clue where any of that stuff was, so thank you for saving me the embarrassment of asking another stupid question.

[skid jackson]

Dank its not clutch oil .... its gear box oil. the oil is for the tranny and the clutch get lubed via the tranny oil. most guys actually run motor oil or automatic tranny fluid instead of actual gear oil. Put a new plug in it and don't be afraid to pull apart the carb. If nothing else you'll want to see what you've got for jetting. Messing with your dirtbike is a good way to develope some mechanical aptitude. Just take lots of digital pics when your pulling things apart so you can reference them when putting it back together. Seriously the carb is pretty simple. 4t carbs can be a bit more daunting but still simple. Where the hell is your girlfriends dad?? If he is any kind of a fellow rider he should be showing you this stuff.

[HuskyDude]

Originally Posted by skid jackson

Dank don't be afraid to pull apart the carb. If nothing else you'll want to see what you've got for jetting. Messing with your dirtbike is a good way to develope some mechanical aptitude. Seriously the carb is pretty simple.

Well put skid...
If you're riding any type of motorcycle you should at least know how it works. Jetting is one of the fundamentals of riding a 2T.
Start looking on the web on how a 2T carb works and understand it's principles.
It really isn't that hard. But before you get into it a basic understanding would go a long way.