by JimDirt » Wed Jan 06, 2021 8:52 am
Have you checked the oil filter ??? , if there is going to be metal in the engine side , that is where it will show up .......
So when the bike started again , you were riding , went 100 yards and it just stopped on its own (locked up/skidded to a stop) and would not turn over again ?? .... As Neil mentioned , was there a time delay (15 or 30 minutes or more) where the engine cooled down before it was able to start ?? ......
Have you pulled the clutch cover (not the entire side case , but the round cover with 5 bolts) to see if there is anything broken in the clutch itself (with tranny oil drained obviously) , like one of the fiber disks breaking causing a lock up ?? , you can also remove all the clutch disks/plates and make sure the clutch inner hub turns , as well as seeing if the basket rotates
Have you tried as Neil mentioned , putting the bike up off the ground/on a stand , either putting the bike in neutral or (with the plug removed in both cases) , putting it in 5th gear and trying to see if anything turns by rotating the rear wheel or kickstarter ??
You may , have to remove the entire clutch side case (water pump and all) and see what the kickstart mechanism is doing
You can also remove the ignition cover and see of anything is broken/jammed in the flywheel (with engine oil drained) , or if possibly the timing chain has jumped or broken , or by removing the timing chain tensioner to make sure it did not break and jam the timing chain .....
If all this checks out good , then the only other option is to remove the head/cylinder to make sure there is not piston or rod damage as Neil suggested , you can do this with the engine in the frame , however if the crank/rod is at fault , then the engine will obviously have to be removed and completely disassembled .... there could also be something locked up in the tranny , but usually the engine will rotate if put in neutral (you did not mention if it shifts smoothly or not) ....
2020 CRF450R
2006 CRF450X

Weiser , Idaho