weird problem starting

Have gone through about a million little problems with this bike. I thought I had the starter/carbs fixed. I left it for the weekend and when I got back I turned the choke on and hit the start button for a second. The bike started up instantly, ran for a few seconds then died. Tried restarting until the battery died. petcock set to prime for a few seconds before. Whats up?

 

ink251, do you ever feel like if it weren't for bad luck, you'd have no luck at all? I mean, look at your last couple posts to the forum:

XJ Modifications » Complete electric makover
XJ Chat » xj550 not starting
XJ Chat » Electric start problem, xj550

The problem is either with fuel or spark. A shot of ether in the air box will tell you which. If she fires up and runs a second or two on ether, you've got fuel problems. If not, check for spark.

 

Tried the ether, a 5 second spray would produce maybe one solid firing and the engine won't start. Checked all the sparkplugs and they all fired and at the same speed. Its weird that it will start the first time on choke, rev up and then die not to be ressurected for a day or so.

 

See if you can ballance the choke/throttle when she fires to keep the motor running.

Try setting the fuel to prime and leaving it there. Then start the bike.

All carb boots tight? Gone through and checked floats etc?

 

Yeah if it'll fire with ether, then you have a fuel problem (you didn't mention whether it'll fire off of ether repeatedly though.. ie: spray-rev-die-spray-rev-die). First and easiest thing to check is to make sure you have fuel flowing. Pull off the fuel hose and turn the tap to PRI. If you get nothing (or a slow dribble), your in-tank filter is clogged.

Other problems could include:

Kinked/clogged/melted fuel line.. Pull the hose off the carb fuel rail and make sure fuel flows freely.

Water in the fuel or bad fuel.. Drain the carb bowls into a cup and look at the contents. If there's water in it or its a funky color, you have your problem. Since gas floats on water, the water (and any other crap that's sitting at the bottom of the tank) will get into your carbs and sit there until it's drained out. The more water collects in the bowls, the less room there is for gas. Drain the tank completely, then partially fill with fresh fuel and drain again and refill. Then, with the fuel tap set to PRI, open each carb bowl drain and flush until the fuel runs clear. Set the tap back to RUN and give it a go. ** This is the most likely problem **

Really dirty carbs.. Its unlikely to cause a complete and sudden no-start condition, usually thats a gradual thing, but if you disturbed the bottom gunk and/or your in-tank filter broke loose, it's possible for the carbs to foul suddenly. Carb rebuild is in order.

 

Energi2er had a similar problem. A new set of plugs helped as his old ones were fuel-fouled. If you determine that it is not a fuel-related problem, throw a set of new plugs in her and see what happens.

 

Im gona run some fuel through the drains. I just got new sparkplugs less then a gas tank ago. I pulled them out and the heads were already black. This is probably because when I get it going I leave it idling on choke to warm it up. I have an inline fuel filter, is it possible that im too low on fuel to start the bike but the filter still shows fuel? It couldn't be my carbs, I just rebuilt them. It could be the mixture or sync tho. Has anyone used colortune here? What color do you look for?