Stalls out once warmed up

Hey all.

I've got an '85 XJ700 that's been sitting more or less unused all summer (haven't been able to get out and ride due to other projects/work etc). So I finally had some time to fire it up, and it started relatively quickly for not being run much this year. Had a small issue with the number 1 cylinder not firing (this has happened before, usually in the spring after a winter of disuse). I swapped the 1 and 4 plugs, and seems to be running on all cylinders now.

However, the problem I'm running into now is that I can't seem to get it to stay running. I g0t it started (with the choke on), let it run for about 5 minutes, until I was able to have it idling with no choke. My goal was to just let it idle for awhile to let it loosen up since it's been a long time since I've ridden it. After about 10 minutes of idling, it slowly sputtered out and stalled, and didn't seem to want to fire up again. I first suspected the gas, so I ran out and got some fresh gas (non-ethanol premium) and came back about 20 minutes later, topped off the tank and tried again. Same issue. It starts, runs and idles for about 10 minutes, and slowly stalls.

Could it be the spark plugs? Or am I running too rich? Is it basically slowly flooding itself? I smell a little gas, but that might just be lingering odor from filling the tank. I've never really messed with the fuel mixture before, or done much with the carbs at all for that matter, but I've had the bike since 2010 and never really had any issues that warranted having to take the carb apart.

Anyone experience this before, or know what the culprit might be? Any advice is greatly appreciated, as I'm anxious to get out and ride with what remaining season is left.

 

Valve clearances were last checked when?

 

1. Did you have any Stabil in tank and carbs? Stale fuel will cause problems you decribe...try a tank of Seafoam and fresh fuel...I'd drain old fuel if you have not filled up. You may have to end up pulling carbs and cleaning .

 

Take a look at the plugs. Sooty? Wet? My 700 did this when I first got it and a thorough cleaning of the carbs, properly wet setting the floats, setting the pilots screws with the use of a colortune plug, and properly syncing solved the problem. Seafoam might help, but the fact that you have problems with the #1 cyl indicates carb issues. Probably fouling that plug first which explains why it goes away when you switch plugs. This ethanol gas can go bad fast so I make it a habit to ride my bike at least once a week all year, and keep stabil in it in the winter when the rides are shorter and I don't have to get gas as often. Also, what's the condition of your battery. If it is weak that may be the issue since I understand that the alternator doesn't kick in until about 2000 rpm, or at least I think that's what been mentioned here. Not a bad idea to keep a battery tender hooked up.

 

Battery is relatively new (last year), although I did not have it hooked up to a trickle charger. It turned over and cranks fine, but I'll give the battery a fresh charge just to make sure. The plugs were definitely sooty, but not wet. When I first got the bike I seemed to have an issue with the #1 plug being a bit wet, but I had replaced all the plugs and hadn't really noticed it being wet since then. But they are sooty, which was why I was leaning toward maybe too rich of a fuel mixture.

The old gas that was in it was also 91 non-ethanol with a dash of Stabil in it from this past winter. Not the worst gas, but still 9+ months old, so that was why bad gas was my first thought as to the cause. I did not drain the tank before I added the fresh gas, mostly due to the fact that it was only about 1/4 full to begin with. So I suppose it's possible that I just didn't run it long enough to really work through to all the new gas. I had added a bit of Seafoam yesterday, I'll try to run it some more so it mixes into the carb to see if that helps out at all.

I haven't checked the valve clearances since I've owned it. For the most part I haven't had many issues with the bike; I usually try to run it at least once a month in the winter (assuming its warm enough to start). I'm hoping the problem isn't with the carb itself. I'm short on space to get into any serious disassembly projects, and really don't want to bite the bullet and bring it to a shop to get worked on for the rest of the riding season. Not to mention few places around the Capital District of NY seem to want to deal with these maxims in the first place! One guy even told me, "eh, we don't work on bikes that old - too hard to find parts for." Seriously? A quick google search and I felt like I found at least 75% of the parts for these XJs. But I digress.

Thanks for the advice. I'll try the quick solutions first and see if that makes any difference.

 

And there it is. Starts fine; stalls when warm, won't restart.

Check clearances. I'll wager that you'll find that all of the exhaust valves are tight.

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