Lost power, wont start!

[stevo82]

Hi,

 

I have a 2003 WR450 which I bought second hand for cheap, 5th gear was broken and electric start slipping, otherwise no major issues. 

I had it for almost 2 years when one day I went through a sharp dip at speed and immediately felt the bike lost power, I rode on for about 150m to where I had to slow down and turn to go over train tracks, when I slowed down and pulled the clutch the bike died and now it refuses to start. I noticed the hot start cable came off from the carb also. 

 

I've cleaned the carb, can see fuel squirting when I turn the throttle, and I have spark. A mechanic told me to take the carb off and give it a kick with my hand over the intake to feel for suction and it has suction so there is compression? I'm going to try and make an adaptor for my compression tester so it fits in the bike spark plug hole to test it, I cannot think of anything else to try. 

 

It does backfire blue flames sometimes after lots of kicking but just wont start.

 

Any ideas?

 

Thanks!!

[FORMA MOTO]

If the bike had so much time on it that the 5th gear was broken, and the start was worn out, more than likely your top and is worn out, and probably the valve adustment is way off.....and probably needs head work too.

[stevo82]

Probably true, but the sudden loss of power and dying?

[mikenash]

A known problem on the 03 model year is the flywheel key shearing off. That's where I'd start

[stevo82]

A known problem on the 03 model year is the flywheel key shearing off. That's where I'd start

I'll have a look at that, but would the bike keep running (with a clear feel of less power) for about 150m until I basically stopped, then die and refuse to start again?

[stevo82]

Should I be able to push down the kickstart easily by hand? I just drained the oil with the filler plug off and pushed down the kickstart a couple of times by hand and theres a lot of air blowing out of the filler hole. I'm guessing thats bad?

[DeepPurplishBlue]

I'll have a look at that, but would the bike keep running (with a clear feel of less power) for about 150m until I basically stopped, then die and refuse to start again?

 

No it would pretty much instantly quit running if the key sheared.  

 

Also, there are no reported incidences of the key shearing while under power.   At least I have never heard

of any.    Usually what happened was there would be a backfire while attempting to start the engine and

the reverse rotation would break the key because there was no give in the 2003 starter idler gear.

[stevo82]

I found the problem, my piston cracked..