[Remi]

Hey guys ! I'm new to the forum and i just bought an 03 450r...

I rode it about 2 times and now it wont start or even make full rotation.. It kind of lock up right after admission when it start compression stroke. The cam "kickback" if i can say that like if the valve were hitting the piston.

I've cheked timing and valve. Timing was off since the tensionner was broken but i did mod it to make a manual one.

Valve spec .006 and .011
Mine were at .005 and .006 and .012 on both exhaust so it is still in spec.

For the timing, i cant align all 3 dot. Flywheel and cam ok but the counter weight is off...

Anyone have an idea ? I bought it 1 month ago and i've been working on it for 3 weeks trying to figure out whats goings on ..

[Back2-2]

Sounds like it's time to go inside to see what happened.
Possibilities :
Cam chain broke or jumped off the lower gear jamming things up ?
Decomp mechanism failed or jammed ?
Failed lower crank ?
Kick mechanism started jammed ?
Any noises you rotated it to check the timing ?
Does the engine rotate while in gear using the rear wheel to attempt rotating [ spark plug out ] ?

[Remi]

Timing is good. Valve ok.
I have replaced the head gasket and the cam chain. Crank is ok as it spin freely when the plug is out.. But it wont when its is in..

The head was not warped at all when i've removed, also cheked with feeler gage and strait edge.. Piston was ok but i did not removed the cylinder to mesure bore and ring gap...

I got pics but i dont remember how to post them here..

[Leardriver]

If you rode it, and it ran ok, then the valve timing is either on or close enough, like within one tooth.
My wild guess is a broken decompressor pin.

[Remi]

I just removed the decomp mechanism and it seens like the weight do not spin freely...the washers between the spring and the roller is not straight... It does make resistance ...

I'll try to fix to that.