78 xs1100 lost power

[sweet78xs]

Hi, I am a newbie to the xs 1100. First I would like to say WOW, what a bike. I love it. Today, I gave my mother-in-law a ride from my house to hers with no problems. After I picked up my wife and headed out for a nice long "maiden voyage" (more than a 3 mile loop) We had a problem. We made a right turn, headed down hill, then back up through a dip and lost a cylinder or two. I'm not sure what happened. It felt like a cylinder wasn't firing. She was doggy and felt like she wouldn't make it to the top of the hill. The tank was nearly empty, but had enough to get to the money thieves scalping dinosaur juice down in town. I pulled in the clutch and revved the engine, but it was still lacking all 4 in unison. At the crest of the hill, we pulled up and stopped. Still running, I revved and the engine was running normal again. It didn't give any more problems the entire 80 mile ride we made.

My question is this: could this be an electrical issue, or could it be a lack of go-go juice heading down hill on one side. There are 2 petcocks on the tank. I hope it was just not enough getting to the carbs.

Thanks in advance,

_Carey

[skids]

It could be low fuel in the tank, bad old fuel, vacuum created in tank due to bad breather cap (my guess), hole in vacuum tube from carb manifold, bad pick-up coil prob for 78 through 80 models.

[jjwaller]

You didn't say if you switched over to reserve. If not, I'd say you were running out of gas. BUT, check the vent on your gas cap anyway. Easy to get clogged, and will cause all sorts of mysterious (suspected) carb problems. If you did switch to reserve, It might be a good idea to pull the petcocks and clean the screens.
Lower sections could be clogged.

[Ken Talbot]

Sounds to me like pick-up coil wires. Sudden, intermittent loss of two cylinders. This is fairly well documented in the tech tips.

[mro]

Petcocks being near the rear of tank could become dry if fuel low enough and hill pretty steep...but as Ken mentioned "Sudden, intermittent loss of two cylinders" sounds a lot like the pick-up wires. Only takes a few minuets to check em.


mro

[planedick]

Down hill

Going down hill the gas goes to the front of the tank and starves for fuel. It's not unusual for one side to go dry before another as there is no connection from one side to the other for the fuel to even out. Usually the right side goes dry first because when it sits on the side stand most of the fuel goes to the left side.