I've got an 89 cbr600f, and from what I know, everything is stock. the emissions stuff has been taken off i'm pretty sure, except I put a slip on muffler on it (2" ID)

the bike's been running fine, except under decel, it seems to pop/gurgle, and spit out a blue flame, so I was trying to figure out what was wrong. I put new plugs in, and took it for a spin. I did a couple cruising spark plug cuts (cruising, then shutting the engine off and pulling the plugs to look at them), and there seems to be silvery stuff on the top of the electrode bend. I was afraid that it was running lean,and that could be part of my piston, but it feels very slimy, so i think it's just anti seize that is dripping onto it when i drop the plug down. I think it would be more gritty if it was aluminum from my piston. I'm a little bit worried that it is running lean, although i havn't ridden it more then a mile , since I was afraid it was running lean. It's still gurgaling a little bit when i let off, but the fact that it was throwing a small flame, is why i figured it was running more rich than lean. the old plugs looked ok.

Do you guys think i should just put around on it for like 20 mileso or so, then pull the plugs and see what they look like, or what?

I really don't think the slip on mufler could have released enough backpressure to make it run super lean....
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It could be a number of things, but the easiest answer is to richen up your mixture a bit and see if it goes away. If it does, YOU'RE DONE.

Where are your mixture screws right now?

If you're nervous about it, it is better to be a little bit rich than a little lean. If it's too rich, the plugs will be sooty and black. Lean, they will be more of a whitish color.

You're right you need to go a little bit farther and get the engine hot before you can tell that way anyway. And try not to remove and install plugs when the engine is warm, cause you're more likely to booger up the threads and then you're screwed.

Good luck!

 

how do i richin it up? is there a screw on the carbs to do that without re-jetting them or anything?
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Go to www.cbrextreme and download the F1 manual. It's easier for you do do some reading than for me to explain it. It's on page 19 of the "section 4-7" pdf. you need a really long, really skinny flathead screwdriver.

 

I have the manual downloaded. so please explain what this screw does exactly?
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I see you adjust the pilot screws, but how exactly should i do it to richen it up, etc?
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adjust the jets.

 

how do you adjust the jets? please explain, i've never had a carb'd engine before on anything.
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IF the "restrictor" caps/tabs are on the pilot screws you won't be able to turn them much at all, like half a turn or something.

I they're on there, CAREFULLY take the restrictor caps off with a needle nose pliers or something. They're held on there with loctite. The actual screw is under there, and it's a brassy color.


Then, you can:

turn each screw all the way in until it stops, count how many turns you did. Should be between 1.5 and 2.5 turns or so.

Back them back out. The more turns OUT is richer. If you were at 2 turns out try 2.5 or something to get a little richer.

This screw only affects your idle and low rpm (up to about 6K rpm) mixture. After that your main jet kicks in.

When you're happy, put a little blue loctite on there and put the restrictor cap back on. If you want to be a rebel, file the little tab off of the side of the restrictor cap while you have it off and you won't have to to the loctite thing any more. But you'll need to check your screws every once in a while to make sure they haven't moved from vibration.

OR, you can just leave the little restrictor cap off and just check your mixture screws every once in a while.

 

my bad, gogar is right, you should be adjusting the pilots first before having to mess with any jetting adjustments.