Help! Bottom end?

[Rmxer]

Hi guys

Have a 98RMX250S and it shat itself on monday! Rode it for about 3 mins and it locked up whilst hooning down a strate. First thought was that i had siezed the top end as when i slowly pushed the kick start down it sounded a little ' grindy '. but once it had cooled down when i pushed kick start down there was still good copmpression and the ' grindy ' noise seemed to be coming from the bottom end. not a very loud noise but happens once on each cycle
So after removing spark plug and exhasut im pretty certain the top end is ok and have also drained gearbox oil and that is all clean too.
Removed fly wheel cover to check for up and down play and there is only a very tiny bit of movement. SHould this have heaps of movement if the bottom end is buggered??
I will eventtually strip it down to find the problem but thoight id ask first for some ideas first
Cheers!

[scott411]

when you move the crank up and down it does not test the bottom end, it test the main beerings for which the crank runs on these,

only way to check bottom end is to take barryl off, then pull con rod up and down

[cheese]

My old RM pooed itself in a kind of similar way once. The race for the bearing let go and pushed out the crank seal. I was lucky as it only put some grooves in the housing, your one sounds like it may have gone the other way.

Also if it's stiff and feels like its grinding on something, don't force it, you could be actually doing the damage instead of getting away with a cheaper repair bill.

Anyway pop the cylinder off and have a look at the crank. If you have to do a bottom end, you need a new conrod, and the crank has to be ballanced and you may as well do the crank bearings and seals.... Then while you are at it you may as well do the piston and rings... unless they are really new/mint.

The spark plug isn't missing a piece of the bottom is it?

[Rmxer]

yeah im not forcing anything when im turning it over and no the spark plug is fine even had a good brown firing end. so bugger sounds like im splitting the cases!!:dodge:

[Buddy L]

hope you have a god job, to pay for the repairs.
My "Big end bearing" on the conrod shat its self a while back, got all bearings replaced and it cost a fair bit for parts. mine was 500 bucks for all the parts.
But i did get a new conrod in that bill.