82 Maxim 550 Carb Problems....at wits end - HELP!

I recently purchased a low mileage 82 Maxim 550. It supposedly sat for years until the guy I bought it from made a "barn find" so he said. The guy said he cleand the carbs, but it still ran bad and fouled the plugs out. No problem, or so I thought. Well, I get it home and tear the carbs apart and the looked as if they had just been cleaned (so he told the truth) but I decided to go thru them anyway since I went to the trouble of ripping them off. Short story is I found nothing wrong. Right jets, diaphrams good, pass the klunk test, enrichment circuit good etc etc. The only thing I found was the air screws were backed waaay out, so I adjusted accordingly.

Put the carbs on, threw another set of plugs at it and fired it off and proceeded to synce the carbs. Ran like a top. Took it out and ran 20 miles and it runs as it should. But. I pull the plugs to take a reading and they are black with soot. I don't get it. They havent fouled again YET, but I am waiting. Any ideas XJ experts? I have done my own carbs for years, but I am second guessing my work on these, or am overlooking something really stupid. I am considering buying a "colortune" so I can see what is going on. Ideas & Suggestions wanted!
Thanks! :roll:

 

Sounds like it's still running rich - did you replace the air filter?

Are the needles height adjustable? If so, where are they set?

 

clippy, welcome to the site. You are deffinately rich. When you set you mixture screws how many turns out did you you go? Should be 2.5-3 turns out to start. After you set you mixture screws did you do any plug chops to see where you were at? If you haven't done the plug chop that is probably where you went wrong. It's easy to skip a step now & then, speaking from experience. You will be looking for a nice even tan color on your insulators. Good luck.
Gregg

 

You might want to check your float heights, if too high it could be contributing. Also, not only REPLACE the air filter, but check the airbox inlet (it ain't very big) for obstructions, check the airbox for a mouse nest, etc.

 

Well guys, float height correct, new airfilter, no airbox obstructions, no adjustment to the needles. Needle height was my first guess, but not adjustable. I was reading here last night and I have to wonder if the guy I got it from doesn't have the main and pilot jets reversed. I didn't check them out when I did the carbs, it is possible they are reversed. I didn't do any plug chops yet, but will when the weather cooperates again.
Thanks for ideas.

 

Main and pilot jets should be different thread sizes - so you can't mistakenly put then in the wrong seat (if that's what you mean).

Now - did you replace the jets? If not, it's possible they might have been drilled out at some point by the PO and are actually larger than the code suggests.

 

Either that or you've got a bad o-ring somewhere or mabe an enrichment plunger that isn't closing off, it's getting too much gas from somewhere, OR

We might be mistaking OIL soot for a rich condition. It may have a couple of stuck (or rusted up) rings and be pushing oil that's being burned.

How long did it sit and did you do a compression test?

Does it smoke? Not necessarily excessively, but on off-throttle or when you JUMP on it? Could also be dried out valve stem seals on those two sooty cylinders.