Hi,been out on the bike today,'04 250 Pro,it wouldn't rev properly so whipped the carb off and gave it a good blow through,put it back together,kicked it over......the bike fired and revved a bit.......then stopped suddenly,now you can't get the motor to turn over,it's solid,any ideas? Cheers.Chris

When you say the motor won't turn over are you saying that it's locked up or it won't fire?

As an easy first step I would pull the pipe off and look into the exhaust port with a flashlight to see if the piston/rings have any scoring.

Hi,it's locked up solid!!!,you could stand on the kickstart!

Yeah, as above, check for scoring inside and on the rings, if you cant see anything give the cylinder a few taps with a rubber mallet, even amount of hits from each side preferably!

Try kicking it over gently, if this has unstuck it dont ride it just yet, Check the reed intake rubber sleeve for leaks or splits... make sure all your carb settings and fuel to oil ratio, maybe your engine wasnt getting enough lubrication? Test your fan also, search up on here on how to test the fan, more likely to find something about this in the sherco section

Your engine may of been overheating? Doubtful though, how long did it take you to clean the carb, was the bike still hot when you put it back together? Before starting pour about 10 ml of 2 stroke oil down into the cylinder, do this when piston is at the bottom of its movement! Kick her up and sit watching it for about 10 minutes, may be a bit of a bitch to start with the extra oil. Observe for nasty sounds, like knocking and things that sound wrong! Give it a ride keeping the power low for about an hour, if all seems fine return to normal!

Whip the cylinder off and check for any scoring on the piston, rings or cylinder... If theres nothing visible give the crank rod a wobble, should be pretty much solid side to side, if loose side to side its probably a bearing. If not loose grab the kickstart and very gently kick it over twice! Will it kick over atall now? if not probably a bent crank rod or something jamming inside the crank itself, maybe a peice of the bearing shot or a problem with the... if it moves round make sure its doing the full motion, if you are not sure about the correct motion the bottom of the crank rod should go clockwise (looking from the left of the bike) down and round!

If this does not happen check flywheel/stator this could be stuck solid and causing your problems? whip them off and try turning the kicker again, does the crank turn now? if not, shove them back on, Take the clutch housing off, remove the plates and check for anything jamming up between the inner and outer! still nothing? Then theres either something jamming the gears or kicker assembly or something broken in there... if its none of these im stumped

Anybody feel free to correct me obviously!

All the best

Jamie

Edited February 15, 200917 yr by shercoman2k8

Put it in gear and see if you can turn it over moving the back wheel, if it moves may be the kick start mechanism only.

Put it in gear and see if you can turn it over moving the back wheel, if it moves may be the kick start mechanism only.

Correct me if im wrong but this is a bad thing to do? if it isnt the kickstart mechanism and it does budge the piston, if the pistons been stuck due to a peice of grit or dirt ect it will only score the cylinder more? Which does get very expensive, ive learnt from a dodgy beta

and revved a bit.......then stopped suddenly

What do you mean "revved a bit"? Do you mean 2 secs or 2 mins?

Edited February 15, 200917 yr by TooFastTim

What do you mean "revved a bit"? Do you mean 2 secs or 2 mins?

2 secs,got it apart this afternoon,bit of scoring,but not too bad.....gonna put it back together after a clean up,see what happens........watch this space,cheers lads for your help.

Sounds like there was an airleak and it revved it's nuts off and then had a partial seize. You were lucky by the sounds of it. Please keep us up to date.