1982 XS400RJ won't start/stay running

[shadi93]

First off, Hi. First timer to these forums. I got an 82 XS400RJ for free from a friend who had it sitting in his garage since the year he bought it. It only has 977 miles on it. Soi've spent a few weeks trying to get this thing running. After everything I've done I can't get it to stay running. The spark plugs fire, and I rebuilt the carb (might haven't done a good enough job apparently), but it doesn't want to start. When I can get it to start it's not more than a few seconds. I'm pretty sure its a fuel problem, but would anyone know what to look for? I got it running and cranked it up to 3k RPM and held it there to see if I could keep it going, but after a few seconds it dropped and died out. Thanks to anyone that could help!

 

[DanMach]

Well could be a few things, I'd start by checking the carbs again. Make sure the floats are right (3mm +/- 1mm from the gasket level), recheck the pilot jets and passages, and make sure the petcock vacuum line isn't cracked/messed up.

 

[jmd_forest]

When it will start but not stay running it is almost always a carb/fuel problem. After cleaning the carbs ALWAYS install a fuel filter since rust/dirt from the tank can plug up the carbs again in just a few minutes. Set the petcock on PRI to make sure it not just a petcock failure (bypasses the vacuum activation of the petcock). Loosen up the drain plugs n the bottom of the carb to ensure they actually have fuel in them and then retighten. When all that fails, pull the carbs again and CLEAN, CLEAN, CLEAN. Would probably be a reasonable action to replace the float needle and seat while you're in there. They are relatively cheap. Check the diaphram for holes also. And if you missed it the first time, CLEAN, CLEAN, CLEAN the carbs.

 

[shadi93]

Alright, looks like I'll be rebuilding the carb again. Thanks guys