2003 450 FSE Died Suddenly and No Longer Runs Right!
 

So I bought this 2003 FSE 450 supermoto in March because I thought it looked like fun. Little did I know exactly what a rare and obscure bike a Gas Gas supermoto was.

Here's some background, so the entire time I've had it, it ran great up until this week when the problem started. I only rode it once prior, for about 25 miles, but I ran it a good several times and took it up and down the street.

The problem occurred a few days ago when I was taking it for another ride. It started easily as ever, in only 4 cranks it was purring like a kitten and ran great as usual.
But, about 9 miles into riding, it started to sputter a little, like it was running out of gas, but I had topped it off and it had plenty. I kept riding for another half mile or so in the hopes it would clear up, but instead it lost power completely and I coasted to someone's driveway.
Occasionally while waiting for the tow from my friend I would press the starter to see what it does, sometimes it would crank with no fire, sometimes fire a little. But it never ran.

Then I went to the garage to check on it 2 days later, it cranked and cranked, nothing. So I left it a couple minutes, checked the battery (it's lithium and has a built in indicator) and tried again. Fired up and idled. Seemed almost normal again actually, it idled and I could rev it. It did stall once but started back up. BUT, when I took it just one block up the road and turned around to come back, she DIED on me again same as before!

I don't even know where to start with a fuel injected bike like this. Has anyone had a problem like this? Any help would be appreciated!

I had an issue exactly like this on my 2003 FSE450.
I fully recommend pulling the relays out from near the airbox and giving the contacts a GOOD clean with a wire brush etc. You can pull the receiving wires for the relays out of the sockets one at a time as that way you are not going to get anything mixed up.

Next I would take the relays and crack them open (just be careful) by slowly working around the case seam with a small screw driver or something. Inside you might see some carbon buildup on the contacts so grab some sand paper or a jewellers file and clean that up. Pop it all back together and fingers crossed you have it sorted.

If you still have issues I recommend checking your kill switch and starter switch. My kill switch was a little rough and a good clean fixed it right up :)

Thanks for the insight! I'll be sure to check those relays next time I'm working on the bike. Would be wonderful if the problem was as simple as a relay... Seems unlike a relay failure, but if that's what fixed yours with the same symptoms, hey it's worth a shot.

The kill switch seems to work fine, as when the bike is off and I press the kill, upon release of the switch I can hear the fuel pump re-prime.

Could you describe how yours died, if it was during a ride like I experienced, and would it restart but then die again the next day like mine does? And once you cleaned the relay, did it immediately run again just like before?

I was going for a ride and I got about 2min down the road and it just died just as though I had ran out of fuel. At first it was like a loss of power, then the revs fell and it stalled, it sounded really weird though. I could prime it a bit then it'd run for a little then it'd do the same thing again. It did this many times over (took me over an hour to get back home, lots of hills). After cleaning the relays it was back to normal for another 500km until they crapped out again. I'm just now looking at buying some solid-state ones as I have heard good things about those.

I'm pretty certain we have the same issue. Also make sure to check the stator bolts on your bike, around that time I had some of mine fail and cause one hell of a mess. Do yourself a favour and pull the side cover off and clean it nice and red locktite the bastards in :D

Ok well that's good to know. The relays will have to be one of the first things I check then. Thanks!

Symptoms also sound similar to what stranded my buddy's WR in the woods.
Shearing/sheared flywheel key. It throws the timing off.

Also check your rectifier cause if your battery isn't holding charging eventually the bike will just die... That's what happened to me n my 04 gg crucified along than all of a sudden pop pop almost died pulled the clutch in gave it a light rev and she died tried to fire her up again n nothing tried a couple different things than swapped batteries with a mate bike and it fired straight back up luckily his bike wasn't fuel injected so he kickstarted his bike and bout 15 mins later my bike died again I swapped batteries with 3 different bikes that day wat a nightmare...
anyway got the rectifier checked n wasn't pushing out correct readings ordered a replacement plugged it in n hey Presto battery charging again

I have had similar experiences with other makes. A loose cam chain can jump teeth and change the timing and kill the bike. Automatic cam chain tensioners can and do fail. Proper tension and timing could be your fix, expecially since it died while running.

Your problem really sounds like the rectifier/regulator problem that I had. Hard to start, really inconsistent and sometimes worked fine. Once I changed rectifier, it has run like a champ

I'm sure it can't be this simple but it's worth noting that my '05 kills a plug right at 1000 miles....it started sputtering once and freaked me out. Was the plug. Once we'd just came out the woods and it was running great.....died going down a dirt road about 2 miles later! Now, if it's not running right or dies I just right away go for the plug.

The plugs always look great....hooked the last one to the lawn mower and it did not spark. I always use the stock NGK. It just seems to kill them. I've owned a lot of bikes and this one kills plugs more often than anything I've ever seen, 4 or two stroke.
Ed

Got an update to my situation...

So I put in a new spark plug. Old plug looked somewhat fouled, black and wet?

It sometimes starts and sometimes doesn't. But barely runs when it does. Idles sometimes, but will stall if you try to gas it.

Sometimes it won't start at all, then if I kill the ignition and kick it over with the kickstart several times, and try to start again with it turned on it will start and idle again. Till it stalls, then it won't start until I repeat that kickstart procedure.


Fuel pump almost seems to sound weird. Sounds like it's cavitation/sucking air? Also sometimes after cranking it over I could hear it whining for a second and the whine was louder and quicker.