Won't stay started without enrichment fully on

Hi all...long time lurker and fair weather rider. I'm just now trying to get my '85 Maxim XJ 700 on the road and have run into a problem that I think has a straight forward answer to.

I changed the plugs and noticed the old ones coming out were soot black. When I got the bike started, it needed the enrichment opened all the way just to get it started. When I back it off, it just dies. If I try to use the throttle to keep it going as I close the "choke," it dies immediately. It definitely doesn't like the throttle at all.

I have a clear fuel filter and I can see gas flowing from one end to the other, so it seems it's getting plenty of fuel. Maybe too much, perhaps?

Ideas and suggestions welcome!
Thanks everyone. Ride safe.
Cheryl

 

Deffinately sounds like it is time to do a good carb cleaning/rebuild, and gettting the valves checked, and adjusted to spec. Followed by a running sync, and colortune.

Ghost

 

Definitely too much. Black: operating too cold, usually from too much gas. (If it's dry black, almost certainly too much gas--if it's oil, though, it's much worse. I'm assuming you don't mean that.)

Sounds like it's waaay too rich. What's some history on the bike? Carbs ever been serviced? You ever touched the mixture screws?

It's odd to have it running so rich, but need the choke full blast... You should get some new spark plugs first.

The mixture screws are little flat-head screws on the top of the carbs, one on each. Take a mental snapshot of its current position, and then count how many turns in you take each one before it locks tight--write that number down for each. A happy number is between 2.5 and 3 turns. Five is maximum acceptable (if it was looser than that, it might as well have been five, and given how rich the mixture was, I'd imagine someone didn't know what they were doing putting them back in.)

Then try and put them each a half turn back from wherever they were (a half turn is HUGE with these, but you are obviously very rich so we'll start there). Take a look. Still black? Make another half turn until color changes. Ideal color is somewhere from gray/tan to paper bag brown. White means lean. If you hit white, loosen it a 1/4 (or less) and try and get it back to some color on that white.

The bike needs to be at OPERATING TEMPERATURE, however, to actually do this fully, so you need some ballpark adjustments to get it running well enough to ride it for 30 minutes first. So after some tightening, see if it will start and idle on anything less than full choke--once you get it SOMEWHERE that you can just drive around on it, ride it around before continuing.

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All that being said, if you've never serviced the carbs, you probably need to. What's the history on the bike? Is this a sudden change, did it used to ride fine? If you're lucky, though, this all might work without servicing and you might get away with riding for a while before *needing* to touch them.

It would be ideal to have "colortune" plugs. This is a poor man's way of tuning.

Let us know what you see. Rich is a way better problem to have than lean!

 

Hi everyone,

Thanks for all the feedback. A little history:
The bike's carbs were pulled a few years back with the help of Rick (I think he goes by O'matic or something like that on here).

We cleaned and adjusted everything and it ran beautifully ever since. However, the bike was on the road for only a month or so early last season (2011), but not again for the rest of the year. I did install a brand new battery in early 2011, too.

When I had it out, it did seem a little rough, but it ran for me. I'm lucky to have a big garage, so it's stored inside all winter. A little Seafoam was run through before winter came, but that was after it sat for the summer and fall months. Battery was pulled and put on a trickle charger. Oil & filter changed. Air filter changed.

Just before starting it today, I installed brand new plugs. I didn't pull them when I gave up on getting it going (it was too hot and I had to be someplace), but I certainly will pull them tomorrow.

The old plugs were black sooty....dry, not oily. I am aware of the mixture screws. We adjusted those during the carb clinic. They're tough to get to, but I'll see what a slight adjustment will do for it. You said dial it counterclockwise to lean it out a bit, right?

I'm in NH and would not pull the carb rack off without a more experienced person here to help. Besides, I don't have a Colortune or a YICS tool, either. Is anyone from NH that might have those tools and the know-how? Otherwise, my only option is taking it to Yamarobber....ugh.

Thanks again for the feedback. I'll post again the color of the plugs tomorrow.
Cheryl

 

Well if RickCoMatic went through your carbs with you, then you've got a set that fully rebuilt = GREAT START!

But gas sitting in your carbs that long will gum things up . Rick himself even posted a thread a couple years back about how he had to "go through the carbs again" because he didn't put away the bike right before the winter.

I had the same issue when my bike sat for 5 months after an accident. Whipped the carbs off the bike, 3-4 hours of a THOROUGH cleaning, and it fired up, no problemo.

Lucky for you, all you need to do is pull the carbs and do his Whole 9 Yards cleaning again. Then you can sync everything up, adjust your mixtures, and you'll be on the road again!

Oh and turning the pilot mixture screws in (clockwise) leans the mixture. VERY small turns, 1 or 2 degrees at a time.

 

Yep....you're gonna hafta go through the carbs again. You have the classic description of what happens when the main jets are plugged.-- you're running off of just the enriching circuit, and when you throw the "choke" off, you're starving it. Time to clean 'em out again.

You DON'T need to go the the 'robber. You DO need to do it yourself, because you WILL be there again, so you may as well jump right in and get your feet wet. Since you've been in them before, you may find that a simple cleaning will do the trick. Sometimes you get lucky that way. but, pull each jet and check it ANYWAY.

Keep us posted.

Dave F