I have a 01 400ex and recently i have noticed a ticking noise coming from the motor i cant pin point where its comming from its either the topn or bottom end, it rode fine until just the other day it bogged down even at full throttle it bogged worse n worse then just shut off and wouldnt spin back over, thought it locked up but after about 20 min. and i got it towed out of the woods, it started up ran fine didnt miss a beat but tht ticking was a lil louder, so i rode it a lil more and it ran fine till it bogged down again and shut off, this till it would spin over just wouldnt fire and after letting it sit for 20 min. i got it started but it now seems to have a lil knock to it, what could my problem be?? Also i pulled the dipstick and the oil was cold and i had been running it for three hours?? Im thinking its time for a rebuild, how much is tht goin to put me in

 

well ik a kid who had this problem with his kx250f fourstroke. it bogged. and would start and run. and it would bog and shut off. i guess it was the valves needed adjusted. but the part where u ssaid the oil was cold was weird

 

Did you check your cam chain tensioner? If not could be a stretched cam chain. See later posting of a cheap fix for that - works great. I milled out a cap nut and installed it on the front of the cam chain tensioner for more reach. Worked great on a Rubicon.

 

I'd say your oil pump failed and you heated up the piston and rings, and they expanded to the point where it couldn't move. Then after a cool down, it shrank and worked for awhile again. But you've also damaged something in the process. I'd say you need to take the jug off and take a look. Don't run it again until you have a look.

 

Definitely the valves, we were adjusting my dads valves and when we started it we heard a ticking then adjusted them and it really helped, i forget if it means they are to tight or loose?!?!?

 

i doubt its the valves i had the same problem,my oil pump failed,the piton melted and when it cooled down it freed itself,and i guarantee the heat from the oil pump failing stretched that cam chain,you need to tear the top end off get it bored,new piston,new cam chain,and put a new oil pump in it,mine started to bog then when i got up to 3rd it bogged bad then just shut off,by the time i washed it and tried starting it back up the motor was cool and it started up like nothing happen,well i tore the top end off and sure enough there was aluminum and scratches in the cylinder walls where the piston had stuck,i put a new cylinder,piston,and oil pump in it and its been running great ever since