Need some carb issues advice

Ok First things first I guess. 81 Midnight Maxim XJ650. Bought off a friend of mine, who has only had it for about a year. Hasn't done much to the bike - so it needs some love, no doubt. It runs ok, but definitely needs to be checked over and probably have the carbs rebuilt, etc.

Right now, when you start it up, it fires up easy. Idle is a little iffy - kida all over the place. It will run for about 5 minutes just fine, and then after that the far right (#4?) cylinder stops firing.

This is what seems to be the issue to me (novice). It would seem that while sitting - the bowls fill? - but after it's running, the far right one is draining and not getting enough gas. The bowl seems warm compared to the touch (the others seem to stay cool due to being filled with gas?) I've checked things like the plug with the cap off to see if it was getting wet, ect - everything seems to point to the carb not getting enough gas.

While I know that a rebuild is probably going to happen here very soon - any suggestions as to what might be the main cause of this issue? Vacuum leak? Clog? Anything I should look for initially to see if I can just clear this problem up a little? Thanks and if I said anything too stupid, I apologize. Newbie.

 

Sounds like a full carb rebuild is in your very near future.

You need to pull them and start checking them for gunk. More than likely #4 is completely clogged so there is no fuel flowing through it.

There are several great posts here on carb cleaning. RickCoMatic did a feature and Chacal also has a detailed post. One of the members did a very nice pic essay.

You probably also should plan on replacing the throttle shaft seals while you are at it. This will require breaking the rack, but it is not as bad as you would think. Be very organized and very methodical. Once you get this nailed, it will run much better.

 

they actually didn't look all that bad when i opened them up today. and seemed to be unclogged, but i could have easily missed something.

 

Maybe when it gets hot your #4 valves are not sealing. I would check the valve clearences. Give the carbs a once over and check your fuel flow to the carbs. (open the drain screw when the cylinder stops firing.

 

I suggest you try a soft or hard clean as described here:
http://www.maxim-x.com/seafoam.html