Bike Starts, Runs, then Cuts Off

[thewright1]

Hi All,

I'm having an interesting problem. When I start up my bike, it runs for a minute (literally), but then cuts off. I have the choke enabled and it still cuts off. Sometimes it's a little more difficult to start then other times, but it eventually starts. I thought maybe I just didn't have enough gas in it, so i put about a quarter tank of gas in it, but I'm still having the problem.

I did change the exhaust headers and right now there are no mufflers on the bike, I don't know if that has anything to do with it. I also noticed that the bike smokes a little but I'm assuming it's because it hasn't really been ran in a long time.

Another thing I noticed, and I'm not sure if this was actually making the bike cut off or if it was coincidence, but when I'd rev the throttle (to try to keep it running) the bike would just cut off. I unscrewed the screw at the bottom of the carb bowl to see if there was gas getting in, and there was gas there. Any ideas on what could be happening?

[psycoreefer]

what do your spark plugs look like?
Have you made any attempts at cleaning or adjusting the carbs?

When my 81 did that I fixed it by replacing plugs with new - and cleaning and adjusting the carbs.

[dbeardslee]

I did change the exhaust headers and right now there are no mufflers on the bike

That's going to affect your mixture. Before I started diddling around with the carbs, I'd get the exhaust setup the way you're going to run it. What kind of exhaust did you change from and to?

[thewright1]

The carbs were actually rebuilt not too long (in December) and the bike hasn't been rode since then. Spark plugs haven't been changed in a while, when I got the bike, it had been sitting for about 5 years and no telling when the plugs were changed before that.

[psycoreefer]

That's going to affect your mixture. Before I started diddling around with the carbs, I'd get the exhaust setup the way you're going to run it. What kind of exhaust did you change from and to?

True

If you want to do the "least" work then get the exhaust set up like you want it, otherwise you'll mess with the carbs, get it running then add the exhaust which will throw the carbs off again and you'll have to adjust for the changes.

Be advised that if you don't run mufflers it will be very hard to get the carbs tuned right. The engine needs some back-pressure to work as designed.

The carbs were actually rebuilt not too long (in December) and the bike hasn't been rode since then. Spark plugs haven't been changed in a while, when I got the bike, it had been sitting for about 5 years and no telling when the plugs were changed before that.

Rebuilt by whom? how much do you trust them? Many will attest to the inability of shops, mechanics, and PO's to properly rebuild and clean carbs. Unless you've done them your self you don't know what your dealing with.

The fact that it hasn't been rode since the carbs were rebuilt is a clue - could mean that it didn't run well enough afterwords to ride, which probably means they either didn't get all the way cleaned, or were improperly adjusted after the rebuild.

[thewright1]

I did actually ride it once after I got it out the shop for the carb rebuild. The bike was leaking gas through the carbs when i first turned it on, that's why i took it the shop in the first place, so he (the mechanic) told me since the bike had been sitting for so long, it would probably be best to rebuild them.

A lot of this was my fault though. Being a rookie, I pretty much stripped the parts that I wanted to replace (instead of doing them one at a time or as I was replacing them) which is the main reason why I was never able to ride the bike.

[dbeardslee]

If the bike sat for several months with gas in the carbs, and you didn't have any kind of stabilizer in the gas (seafoam or stabil) chances are the little jets for the enricher circuit at the bottom of the float bowl's are grunged up. Try cleaning the bowls and see what that buys you.

[CatatonicBug]

I would vote for fuel starvation. It's either a kinked fuel line that is preventing a strong enough flow, or clogged pilot jets like dbeardslee mentioned. Possibly even clogged petcock screens in the tank.

[XSokieSPECIAL]

pickup coil wires!

[thewright1]

Ugh, just when I thought I was so close to having this thing running. Thanks for the info guys.

[dbeardslee]

or clogged pilot jets like dbeardslee mentioned

Not the pilot jets, the little enricher jets that are pressed in to the bowls. One way it shows up is weird stuff going on when you pull the choke, as described. Cleaning those is a rite of spring for many members.

[bikerphil]

Had a similar problem, turned out to be corrosion on the plug for the P/U coil wires in back of the fuse panel.

[BigRed]

My bike was having two problems sumultaneously that caused symptoms like yours.

One problem was leaky intake boots; you can check this by spraying a little WD40 or Starting fluid on your intake boots while the bike is running. If the RPMs go up, then your intake boots are leaking. You can either seal them up or replace them.

The other problem was a broken pick-up coil wire. When your vacuum advance pulls the timing assembly, it pulls the broken wire, and you lose your spark. To check this, remove the timing cover on the left side of the engine (four 5mm allan screws). There's no oil in there or anything to leak (at least there shouldn't be). You can either run the bike and fiddle with the wires to see if you can make it cut out, or you can just pull on the wires to see if they stretch. If the wire stretches, it means the copper inside is broken. There's a fix for that if you need it. I just did it last night... took about an hour because I'm slow at soldering, and it cost about $14 for wire and heat shrink.

[motoman]

Fix it yourself with the help here. Unless you KNOW the mechanic is "old school" and specificlly knows what issues these bike are notorious for, do NOT let them work on it, period. Easy way to find that out is to ask one or two questions pertaining to known XS11 issues that you already know the CORRECT answer to based on the knowledge here and see what answer you get........will really surprise you what you will get for an answer sometimes. That all it takes for for your decision as to who should be wrenchin' on your scoot.

[thewright1]

Fix it yourself with the help here. Unless you KNOW the mechanic is "old school" and specificlly knows what issues these bike are notorious for, do NOT let them work on it, period. Easy way to find that out is to ask one or two questions pertaining to known XS11 issues that you already know the CORRECT answer to based on the knowledge here and see what answer you get........will really surprise you what you will get for an answer sometimes. That all it takes for for your decision as to who should be wrenchin' on your scoot.

Thanks motoman, I ended up fixing THAT problem. I started up the bike again when I got home, and it turned off on me again, but I have an angel of a neighbor who comes out every now and then and talks to me while I work on my bike, and he told me my carbs needed some re-adjusting and he took a flat head drill bit and did some work on it for about 3 minutes. Not only was the bike staying on, but I was able to drive it up and down my complex. I now noticed I have another problem with the bike. I think I'm having a second gear issues (yeah, the one that's in the tech tips). Its almost like the gears were slipping up on me. This is for another topic though, so I'll find that and post it there.

Thanks for all your help on this issue you guys. I was so ready to just give up on this thing. That's why I love forums.