I was riding my 2005 kx 125 and it suddenly started to slow down and stop. At first i thought the chain had jammed but it hadn't. It was like the engine locked up. It will kick but wont start, what could this be?

Is there gas or diesel in tank..nozzel can b mistaken. Is fuel gittn to carb. Cud hav vacuumleak. Ignition wiring worn like aplug cable. May hav ovrheated fora while..aircoold engines cant ride slow for long..they need to breathe lika horse

Wind noise?

Check the cylinder with a compression gauge

Dont waste your time looking for something else. Go ahead and pull the spark plug and do a compression test. It should have at least 100psi. If not,its time for a top end rebuild. It gets worse when it gets hotter because the ring gap expands,and loses what little compression it has. Best to check the compression and rebuild the top end now,before the piston or rings break,and cause lower end engine catastrophe...

change the plug then drain the carb and ck compression and that will tell u the story

If its running for about an hour before trouble,there is not a lot wrong.Have a real good look to see it has the correct spark plug.This doesn't mean the original type but by looking at the plug and its colors it may be the wrong heat range.This is often the case with different styles of riding and any mods done to the bike.Next ride,take another plug with you.When the bike stops,put the other plug straight in and see if that gets you going.This would be the 1st place to start looking for the fix to your problem.Hope this helps

what do you mean it slows down, then speeds back up, is this when riding or is it when the engines idling?

mate there should be an oil seal on the lever coming out off the engine if not get it replaced

is it getting fuel? try tipping a very small amount of fuel down rhe plug hole, replace the plug if it fires you have a carb problem.