400ex wont start,please help

[AJT87250R]

my son has a 400ex, we were out riding he was running along in 3rd gear when quad began to spudder and died. he was initially able to restart it but it spuddered and smoked a little. now it will not start at all .if you give it any gas while trying to start it backfires. carb has been cleaned and checked and i have spark we have compresion because it wont roll free in gear. thank you for any help on what to look for .

[bman863]

mine did that recently. my problem was that the clutch cable was frayed and it wasn't pulling in as far as it needed to in order to engage the clutch. it could be many things. that is just one. hope it helps.

[AJT87250R]

i checked clutch engagement and it is ok any other suggestions would be more than welcome thanks bman

[FoxMxRiders]

check the compression with a gauge because you can have a restriction when you want to roll free but not enough compression to start.

Change the sparks plug
Clean your air filter