n00b here. My '82 XS400J cut out on me when downshifting on an off-ramp. Any ideas?

[natoe33]

I had just picked up my bike from the Craigslist seller and was taking it for a little ride to test it out a little more than my test ride. It is my first bike, but it seemed like it was riding fine. I rode about 7 miles at around 45 mph and about 15-20 miles on a highway at 65-70 mph. The temperature was around 75F at the time. The oil is clear and there was enough (maybe too much) oil. I downshifted one gear to start engine braking as I was taking the off-ramp. The RPMs shot up to around 5K from a coast and then it just quit on me. I coasted the rest if the way to the light and tried starting up again to no avail. It cranked when I held the ignition and it sounded like I was getting some combustion, but it wouldn't start. I pushed it to a nearby parking lot and called my girlfriend. I wasn't sure what it was, so she brought jumper cables. The bike sat there for about 20 minutes and we figured hooking up the cables couldn't hurt, so we tried that. It started up fine. I'm wondering if maybe it overheated (even though I was doing 70, it wasn't TOO hot out, and it's air-cooled) and the rest period allowed it to cool sufficiently, or maybe I released the clutch too soon/fast and it somehow flooded the engine, or what. When I was riding it to her place after that (top speed of 50mph), it died two more times but started right away when I held in the clutch and hit the ignition.

I don't have much mechanical knowledge. My most extensive auto repair has been changing plugs and wires. Please feel free to ask questions if you have any ideas.

 

[akronevan2]

Smell the oil. Does it smell like gas at all?? If it does smell like gas, change the oil. That should keep it running for a while. Use diesel oil. If this is all the case, you may have a leaky petcock.

Btw, welcome to the forums. This place is great to answer a lot of your questions and to give you ideas of what you may want to do to it. Feel free to post pics, when you can.

 

[dellrio]

Check out your carbs, I had about the exact same scenario happen to me, and the nut that holds the needle had viberated loose and was keeping the float pushed down and it was flooding the engine. It was running very rich, and killing it, at full throttle i was at 50 MPH and sputtering the whole time.

 

[natoe33]

It seems like it's running "normal" at highway speeds now, but I haven't gone that fast for an extended period of time since that first day. I haven't had a lot of spare time since that day so I'm just getting around to changing the oil this weekend. I'll let you know how that goes.