HELP!! 2003 450FSE Won't Start

[racepaul]

My GG won't start. It has spark and compression and the fuel pump is working. I have also checked the cam timing and valve clearance.
My first problem is the starter won't turn the motor over more than one revolution.I have done the following.
new battery
cleaned all connections
had the starter cleaned and tested at a shop
I have tried to kick start the bike with no luck. Every once and a while I got a backfire into the airbox.
Any input or suggestion would be greatly apprieciated.

 

[stainlesscycle]

i'm not familiar with the gasgas 4t, but i know on other modern 4t that i've had, these are the symptoms of bad autodecomp lobe on camshaft. i'm assuming the gasgas has some kind of autodecomp on the cam end... backfiring into airbox is usually cam timing/cam chain slack

 

[Qui-gon]

Forget the kickstart its more of an ornament than anything useful although there are some that will start that way. Try a set of jumper cables and a good car battery. If it spins at slow speed still investigate the starter. There are a couple of threads on here regarding starters on the earlier models.

 

[jostby]

If the starter is dragging (and pulling down the voltage) there won't be enough voltage to run the electronics while the starter is turning. Hook a volt meter up to the battery and spin the starter. How many volts after about 2 seconds? Shouldn't drop below about 10.5 or 11v (this is a guess on my part). Ideally it should probably remain above 12v. Fuel injection and ECU's need more voltage to start/run than plain old electronic ignition (this all while the starter is spinning).

The "once in a while backfire in the airbox" could be from intermittent electronics due to low voltage.

I hope this helps. Let us know what you find!

 

[bergerhag]

Does your starter lock up after a short while and then stays silent? If so, you are either having a problem with autodecompression not working, or a power issue, perhaps cables are too weak, or your battery has too low CCA (cold cranking amps).

If your starter "cries", and engine is not turning, then your sprag clutch might be shot and needs replacing. I am not all sure on the 2003's, but one of the starter gears might have some kind of clutch slip function, to protect starter in case of backfires, and it might be slipping too easy. Anyway, if you have a crying starter, a teardown of the gears and flywheel is necessary.

Shoot a video of a few start attempts, post it on Youtube and link it to us, it will help us in helping you.

 

[racepaul]

O.K. After some inspection it seems that the motor rotates fine until the the point that the auto decompress hits the valve, at that point the starter won't turn the motor over. The auto decompress does not seem to be compressing the valve enough to release compression.
It seems to be a problem a the 2003, will the 2004/05 cam fix this and is it a direct swap.
Thanks for all the input I appreciate it.
Paul

 

[stainlesscycle]

on other bikes, the autodecomp lobe is pushed out by a spring - sometimes this spring is worn/hung up and won't let it operate properly. sometimes the lobe has wear which doesn't allow it to compress (more common)..

 

[mike989]

450 won't start

race,
The 04 cam is direct replacement. I don't know if it will fix the problem. I changed the cam on my 03 a few years back, so I know for sure the 04 will drop right in.

 

[racepaul]

Mike
Did you change your cam to resolve a starting issue?
Thanks
Paul

 

[mike989]

race,
No, not to resolve an issue, I did it to prevent an issue. I also have an 04 450 and noticed how much easier the motor turned over while starting, I asked some questions, found out the 04's had a different cam, starter gears, and some say a stronger starter motor. After I upgraded to the 04 spec pieces and parts, learned a starting precedure it never took more than 3 or 4 stabs at the button to fire the bike up hot or cold. Even before the upgrades it always started, just labored to do so.
The trim setting has something to do with hard or easy starting. Some will disagree, but having the software and messing with the 03, 04 and the 07 for hours, at different times of course, it does makes a difference.