xs400 loses speed and dies after a few kms

[crib20]

Never had a major issue with my 82 XS400, but yesterday it started losing speed and eventually stalled when I was riding. I shut it off, waited a minute or two, and it started up and ran again. However, every km or two it would do the same thing (lose speed, stall, then start up fine again after a minute or so).

Seems like it is losing fuel (but lots in the tank), overheating, or ?. I am not a mechanic.

Any thoughts would be much appreciated.

 

[tstidham]

I wonder if the vent in the tank cap is plugged and you're starting to draw a vacuum and starve the engine. You could try putting the key in the cap and when it starts acting up just open and close the cap to see if it returns to normal.

 

[crib20]

Thanks for the comment ... unfortunately I only have one key so I can't be running the engine and opening the gas tank at the same time (I might be missing something). Is there a way for me to directly check if the vent in the tank cap is plugged?

 

[tstidham]

I'd say just pull it off and give it a good inspection, maybe disassemble and clean. This video is for a different bike, but the concept is the same.

 

[gpounce32768]

Could always go for a ride with the tank lid loose- maybe secure it with masking tape so it doesn't flop around too much.