1998 kx250 problem

Oct 1, 2018
Alright before I start just wanted to say I’m new to this forum and I’m a beginner rider.

Anyways I just bought a 1998 kx250 2 stroke from a really good buddy of mine and got a pretty good deal, anyhow he replaced the top end on it about a month ago has probably about 4 hours on It along with a new clutch and fresh oil. I was riding the other day and kit a straight away wide open when the bike bogged down and shut off, I tried to kick it over and the kickstart was stuck so I rocked the bike back and fourth and got it freed up to find out the kickstart is loose I can kick it with my hand, I’ve read countless forums and watched videos some say it’s the top end others say it’s the kickstart, before I rip this bike apart I want to know what you guys think ? I mixed the oil correctly 50:1