Changed my plugs today on the Dragstar 650. Here are the old ones, they've been on about a year, about 4-5k miles:

rear cylinder:

front cylinder:

Any of you chaps can give us a reading? Too lean/rich, hot/cold, just right, or not? Anything else?

Edit: these pics show the darker side (oooh, Darth!). They are a much lighter tan on t' other side.

i would say they both look good engine running ok

but hey i'm no mechanic

They look a tad fat and wet to me but not familiar with this engine, were they taken out after a good run or not? is the air filter clean? but saying that If its running okay and the mpg is right leave well alone.

They were taken off a cold engine, she had a good run on Sunday, two days previously. The threads are oily because they still had copper grease on them. The ends are dry.

Hmm..If the motor hasn't been started at all since the good run, I would aspect them to be a light biscuit colour all around the porcelain.

Since its an air cooled motor Yamaha do tend to set the carbs a bit on the rich side.

Got to agree with Preload, a little dark but don't look too bad. That gap looks quite big though - that said I don't know what the gap size should be.

Yer they look ok to me, a little rich but nothing too stupid. Again without having the book infront of me i couldn't tell you the gap either but probably worth a check if you can. Atleast you still got plenty of meat on the electrode

Gap's fine, 0.8 to 0.9mm

Noise in your experience with draggie sp's, are they darker on one side than the other?

They look fine to me, slightly more pitting on the front one, colour looks good, no carbon, not oily.

I'd stick them back in, check again in 3 months

How do you mean darker on one side? Do you mean rear cylinder is darker than the front or one side of the spark plug is darker than the other side?

When i changed mine they where near on the same only mine where a tad on the whiter side so i need to buy bigger jets (but thats a side track moment) i am only guessing here so don't quote me, i would think that if one side of the spark plug is darker it maybe because of the way its sat in the cylinder and how it lines up with the valves. If one side is next to the inlet valve its getting hit by a mix of air and fuel so when it burns it will leave a certain amount of soot one that side of the plug, whereas the other side is closest to the exhaust valve and will just be clearing out the chamber.

Again thats only a guess as the inlet valve should spray and coat the whole chamber with fuel/air mix thus coat the whole spark plug. But again before its all compressed its going to spray the plugs first.

Hope that made sense as im on my mobile with fat finger syndrome haha

Yeah noise, that makes sense. I meant darker on one side of the plug. They are about the same from one cylinder to the other.

Think I might try a k&n filter since the plugs appear to be a smidge on the rich side. See what that does...

Yer that will help but to be fair if she is running ok and isn't spluttering up the road under acceleration then she will be fine. But if your coming up to a service you may as well chuck a K&N on her.