[04 crf450]

what would cause a flywheel on an rmz450 to hit the stater and cover and break, any suggestions

[oldtimer]

If it happened after an install of aftermarket part it could have been the wrong size.
If it had been running with it the bolt must have come loose.
They can be tricky to torque properly.

[04 crf450]

the motor has 150 hours on it and that is how long the flywheel has been on it, so it is possible that it came loose. but last night i looked at it again and i realized that the crank had alot of motion side to side, so i called the local shop and they told me that suzuki,ktm,and honda 450's have been showing up at their shop with the same problem and they said that this is caused by hitting the gas before you land, and what it does is it puts stress on the crank bearings, so i think i am going to have to put new crank bearings in it this weekend, which i am not to excited about
if you have another oppinion please let me know

[124]

they said that this is caused by hitting the gas before you land...

???? Either way it sounds like your crank bearings are WAY gone if there is enough play to contact the stator asm. But, "they" are a little bonkers with their description of the root cause. IMO

Good luck with the teardown. Crank bearings aren't bad, just time consuming...and expensive if the stealership is doing it. Bearings are only like $30.

[oldtimer]

How much clearance is between the flywheel and the stator? You would need to have that much play between the crank and the bearing. You would have noticed that before this happened… The bike would have vibrated it’s self apart! I find what they are telling you hard to believe.

I have never torn down a 4 stroke but I have done many 2 strokes and these are a press fit that can be overcome with the heat and freeze method.

[redrider911]

sounds like crank bearings. Tell them your supposed to land on the throttle!!!

[04 crf450]

redrider911, i said the same thing you have to land with you throttle on? and they told me that all of us buying new 450 are the test people for the next generation 450 (i was like yea right a bike should last me at least on race season) , so i don't know if i should believe these people

cr250oldtimer i also thought if the crank bearings were that bad i would have noticed a viberation and it probably would have viberated apart.

[124]

and they told me that all of us buying new 450 are the test people for the next generation 450

Let's give the "all knowing" salesman a hand for 04 450! That's one of the best one's I've heard.

Ridiculous...