HELP...so i can ride mt bike home from work today!!

[frogdink]

bike was running really bad last couple of days, choppy when i give it gas, backfiring etc. the battery light has been flashing this whole time, so today on my lunch break i but i new battery in, (fully charged) and nothing changed, it accually got worse on my way back to work, stalled out when i tried to take off for red lights, running worse it ever had, and the battery light is still flashing....i checked all the connections, cant find anything, what do i do that can be done quickly, and in the parking lot, so i can get home at 4:30......any ideas appreciated...thanks again guys.

[xswilly]

check your gas lines and vacume lines
try putting petcocks on prime

[frogdink]

...

i checked gas lines....where are the vaccuum lines i should check? i just checked the battery and it is charging fine,.

[Snow]

What tools do you have with you? A multimeter by chance?

It's got to be 1 of 3 basic things, one of which xswilly mentions:
Fuel supply (tank to cylinders inc. carbs)
Ignition and timing
Air

Of course, it could also be related to compression of air/fuel, but being that you didn't mention any smoking it's not likely... also, if there is no smoking I'm inclined to agree with willy that it's probably fuel related. Do you smell unburnt gas from the exhaust?

You've checked the fuel lines? Did you specifically check for kinks?

Vacuum lines: I *believe* on XJ's the fuel system is similiar to specials in that you have a vacuum octopus?? If that's true, then IIRC (another big if), then the vacuum lines in question should run from one or two of the carb boots to the fuel octopus...most likely it's just one, but I do not know for certain. Setting the petcocks to Prime should bybass the octopus if all the lines are in stock location I believe.

[frogdink]

...

ok i know the vaccuum line you are talking about, yes it does have the octopus. as far as tools i have, well anything i need, i work at napa, so i can "field test" whatever i need to use. i dont smell uny gas and there are no lines that are kinked up, they are all fine........hmmm

[Snow]

Me trying to troubleshoot an XJ while I've never actually seen a running model is kinda funny...mwahaha

Ok, with that out of the way, let's cover a few more things. I have to ask, just because I've done it myself once, but do you have plenty of fuel in the tank?

Assuming the answer is yes, does your XJ have glass fuses or are they blade type?

[frogdink]

?

i got some gas because i thought of that too, and it has glass fuses, they are all fine.

[Snow]

How did you test the fuses? Looking doesn't count as they can look fine and still be at fault. Also, how are the connectors for the fuses? Did you clean them all up and apply a little dielectric grease?

[frogdink]

?

yeah, i just looked at them to make sure the center wast broken because whoever had the bike before, or maybe the factory had them soildered in in one spot due to vibration i am guessing. so no i didnt really clean them, i will go look again now. any other ideas?

[Snow]

I have one other thought, but it's probably not applicable here. That thought is to remove the two screws that hold the metal fuse panel to the frame, gently pull out the top of the frame and check the generator connector that hides behind it. On my '79 it had corroded so badly that it actually melted the plastic and severed 2 of the wires completely. The bike would run alright but the battery would always go dead within a couple days.

And remember, after cleaning connectors, dielectric grease is your friend

[frogdink]

?

i just went out and started it up and it was running fine, so with it going in and out it must be fuel related right?

[mitch]

Battery light

The battery light is flashing because you didnt buy a battery with the hole in it to install the low fluid sensor did you ? so just ignore that , I think you should check your pick up wires as i bet they are broken . See this link
http://www.xs11.com/forum/showthread.php?threadid=543
Doug

[Snow]

Didn't Yamaha improve the wires in 80 or 81 to prevent the breakage that occurs? It's worth a look though. Also, you might check your coils, especially if the problem goes away after the bike cools down a little.

[Jerry]

Uh, guys, the XJ does't have pickup wires to break. The whole system is solid state. The XJ does have a 'boost sensor' mounted under the gas tank with a vacuum line running down to a port on the intake manifold. Vacuum on one side of the sensor is coverted to an electrical signal which then gets processed, as one component, by the TCI to deliver a timing curve value. If the boost sensor goes out the biKe will still run.

Petcocks should have a PRI or prime setting that bypasses the octopus and lets fuel flow directly to the carbs. Give that setting a try.

Battery sensor...can by bypassed to make the light go out. Look at this Tech Tip:
http://facstaff.uww.edu/fieldsj/mcycle/Connect/

The XJ has a couple extra switches in the system designed to keep you from riding off with the kickstand down or starting with the bike in gear. The sidestand switch ususally goes bad, which will kill the engine or it may cause intermittent problems. (So will a bad, dirty, or corroded ignition switch.) The side stand switch has 3 wires that come out of it and run up to a connector just behind the gas tank. Unplug this connector. I made up a 3-way harness using 3 spade terminals that fit on the bike-side connectors. You want all 3 posts to be in contact; this will make the ignition system think the side stand is in the 'up' position at all times. Switch is no longer available from Yamaha, BTW. Try bypassing the side stand switch and see what happens.

Several people have said - correctly - that fuses can be an issue. Make sure that you are getting good voltage out of the bike-side of the fuses. Replacing the fuse block should be on your list of things to do for reliable operation.

[trbig]

Another no brainer... but make sure the kill switch by the throttle is firmly back... not kind of sitting in the middle somewhere.

Tod