Bonneville America Forums Forums Technical Forums General Tech What could cause it to run rich all of a sudden?

Everytime i check my plugs they've always looked good. Then the other day i noticed the entire plug except the center white ceramic part was sooty black. I haven't touched anything since this happened and there are no vaccum leaks i could find and even cleaned the filter. What could cause it to all of a sudden run rich when i haven't changed anything and it's always run just right far as how the plugs look?

Both plugs or just one side? If it's just one side, I would suggest possibly the stuck float thing causing a degree of enrichening. Since you haven't done anything to it, that's about the only fuel related thing that happens on its own (or going lean from a clogged filter). If the ignition were somehow misfiring or retarding (insert joke here) from a failing component, I would think it would run noticeably crappy (although not necessarily so).

Vacuum leaks would make it lean, not rich. Try cleaning the plugs, removing the air filter, and going for a quick ride without it and see if they carbon up again. If not, your air cleaner's past it's use-by date. It's kinda hard to make them suddenly run rich, unless a jet's come loose or the airflow's restricted or something. Hmm you're not leaving the choke on or something stupid like that? Do our carbs have choke butterfly valves, and if so could one be stuck shut? It's not likely to be a stuck float valve, you'd notice fuel running out of the breather pipes on the bottom of the bike (unless the squirrel condoms are still on? Take them off, see if fuel runs out!).

Bike runs great. Both plugs sooty. Filter was recently cleaned and i cleaned it again but it wasn't excessivly dirty. Took pilots out tho not mains and checked for clogging. No problems there.Floats seem fine because i recently checked them, not because of this but out of curiosity. And no, i always turn the choke off as soon as i possibly can. Wierd ! I guess i'll check the plugs again and see if it's still happening. (threw some old but still good ones in after i saw they were sooty)

I did find the manifold rubbers were very loose, but if you say that would run lean then i guess thats not it. Makes sense vaccum leaks would make it lean, but i checked for vaccum leaks anyways. as for the condoms, i could never find those looking under the bike. Maybe because mine is california and has EVLS?

Daz, your bike has the "Rat Condom" filter, It's where your fuel line connects into the t-shape pipe.......Angelis

If you mean the little V shaped inline filter, i already removed that. I think he was talking about the rubber caps under the bike on some hoses, but i didn't see any there.

I had a similar problem toward the end of last summer. Black sooty plugs and soot around the end of my tailpipe. I changed the plugs and plug wires and that seemed to clear up the problem. I had three seasons on the originals. But it was soon after that my igniter started giving me problems. I began to wonder if the igniter was the problem all along.

Cody

What did the igniotrs cost to replace Cody?

Look under the bike around the intake of the carbs for black rubber hoses hanging down. 2 of them have little black rubber plugs pushed INSIDE of the hoses (those are the squirel condems). Squeeze the plugs out and be ready for some yuk to run out. Not a lot, but it's goooy.

Since both sides are running rich, it would be a really rare thing if both carbs had the same problem, so they should be moved to the bottom of the list of things to check unless the problem started after some work was done on them.

Suddenly rich mixture can usually be caused by 4 things. Reduced air flow or increased fuel flow changing the mixture or weak/late spark or loss of compression causing the mixture to burn poorly.

If the spark or compression were off, you would know right away because there would be a serious loss of power.

Air flow is the easiest to check. Make sure the filter is flowing OK by, as has been suggested, remove it, clean the plug, and see if the problem goes away.
If the problem is still there, take a look at the seat pan. If it has somehow gotten cracked, it could sag enough to block the airbox inlet.
Feel around inside the airbox to make sure nothing is blocking it. While you're there, see if your bike has the rubber tubes in the passages to the carb's. (some have them, some don't) If they are there, squeeze the ends to disengage them and pull them out. Just leave them out, you will gain a couple HP without them. If they've been contaminate with CARB (Calif Air Resources Board) mandated gas, they may have softened enough to collapse when air is being pulled through.

OK, having eliminated air flow problems, that leaves the possibility that fuel flow is increased.
I see you live in CA so, unless you bought the bike elsewhere and then moved there, it came with the vapor recovery system. If the tank was filled vary full, especially in the morning when the gas is cool and more dense, then it sat where it would warm up before any significant amount of fuel was used, the gas may have expanded enough to overflow into the vapor recovery system and filled the canister. If this is the case, exess fuel will cime up the purge lines and richen the mixture. If you are careful to fill the tank no more than to the point where the gas touches the lowest part of the ring at the bottom of the filler neck when the bike is on the sidestand the problem will soon go away.
According to the manual, at least some of these bikes are equipped with a filler cap that has a 1 way vent valve that lets air into the tank but not out. The idea is to force the evaporated fuel through the lower vent hose into the vapor recovery system. If you have the vented cap and the lower vent hose has been pinched or the vapor recovery system has been clogged, it is possible that the tank is building up pressure and forcing fuel past the float valves. With about 1/2 tank of gas, remove and replace the cap in the morning to equalize the tank pressure, then let the bike sit in the sun for a while. When the tank is warm to the touch, carefully loosen the cap and listen for a hiss indicating pressure escaping.

There is one thing that can affect both carbs. Make sure the "choke" is shutting completely off when you push in on the knob.

Thanks GB ! It is a Ca model and it has no internal snorkels, plus the filter is a UNI which i clean more than i need to and just cleaned it after this happened. The EVLS sounds like a possibility. One day not long ago, tho i can't rmember is it was before or after i noted this problem, i DFID fill the bike all the way to the top but with the bike straight up instead of on thew sidestand ! I've never done that, but i wanted to get as much in as possible to eliminate any possibility of bad gas and there was still a fair bit in there.

There are a couple cannisters. I assume it's the big one that would be full of gas? I'll read my hanynes manual and see wjhat it has to say and see if i can find this to be the case. By the way,i don't want to remove the EVLS, but i would like to unhook it. if i decided to cap off the EVLS, what else would i have to do besides cap the 3 carb nipples and remove the overflow hose from the tank on put breather material in it? Is that all or anything else you can think of?

It could be the case of a bad bunch of fuel.

I've gotten gas a couple times since making sure to go to different stations.

Oh, and i took the wheel off again today and checked for play again and closely inspected all bearings (3 of em) and again checked the sproket with a digital caliper and spun the wheel and all that good stuff. Also took the chain off the front sprocket and spun the sprocket listening and feeling for anything unusual in the bearing and all seems good. i cant see the new rear sprocket making any difference as good as the current one is, so i'm really at a loss.

At this point i'm looking at the engine, but it runs great and i balanced it again. Also plugged off the EVLZ and found the hose underneath thats supposed to have a condom on it but didn't. Plugged that and the EVLS and went for a ride. Still nothing. What next? Can't think of anything. Valves maybe? It IS noisy as hell, but then it has been for a long time if not always.

Try a can of Seafoam!

I don't think thats gonna solve it necassarily, but from what i've read i would like to try it anyways as prevention. Do any national chains carry it or is it only available online?

just about any parts house should have it.