Theres back pressure on the kickstart and wont start, could it been the timing??

IF YOUR KICKSTART HAS SEIZED AND IT WON'T TILT BACK IN THE PROBLEMS ON THE SHAFT (REMOVE THE DOMED ALAN CAP BOLT THEN REMOVE THE ACTUAL KICKSTART AND CLEAN UP THE SHAFT AND INSIDE DIA OF THE KICKSTART AND LUBE IT BEFORE REFITTING, MIND YOU DON'T LOSE THE SPRING AND BALL). IF ITS SEIZES WHEN YOU KICK THE KICKSTART THEN ITS THE KICKSTART GEAR OR BUSH IN THE SIDE COVER THATS THE PROBLEM. ITS EASY ENOUGH TO CHANGE IF YOU HAVE THE TOOLS FOR THE JOB. IF ITS A DIRT BIKE TRY TO PRESSURE WASH IT THEN SPRAY WITH WD-40 IT MIGHT HELP. GOOD LUCK IF YOU NEED HELP WITH STRIPPING IT DOWN JUST LET ME KNOW (ALSO LET ME KNOW IF ITS A LEFT OR RIGHT SIDE KICKSTART)

Rock the bike gently forward and back while shifting into fifth gear. Now push the bike forward while sitting on it and see if the rear tire turning will turn the motor. If not, your motor is stuck. If it turns, you have a kickstarter issue.
Many people never learned to depress the kickstarter down until you feel it engage before kicking it through. Kicking from the top slams the gear teeth together and causes damage. You may need to pull of the engine cover to determine if there’s damage.

if there is no kick start shaft out side the crank case then no you wont be able to .

Clutch might be good, but it could be out of adjustment.

One test is with engine off, pull in clutch and cycle kickstarter a few times.

There should be drag for the first 2-3 kicks, then it should free up (the clutch plates tend to "weld up" [just a term] from heat wile running).

If not remove primary cover.

Pull in clutch lever, cycle kickstarter, and watch that pressure plate isn't "wobbling" as it turns.
If it does, you'll have to tighten 1 or 2 of the 3 clutch spring nuts to get it to turn true.

Then adjust the clutch pushrod free play.
In the center of clutch pressure plate, loosen lock nut and back off adjuster screw.
Tighten screw until it you fell it just "touch" the push rod behind it.
Back off the screw 1/4 to 1/2, hold it from turning, and lock down the lock nut.
Adjust the clutch cable so there's about 1/16" to 1/8" slack at the lever end.

Sounds like low compression. Do a compression test,and it should have at least 90psi,..if not,its time to rebuild the top end..(piston,rings,bore)...pretty common for two strokes.

Your clutch plates have become stuck together.The clutch needs to be pulled apart,clutch plates cleaned,and put it all back together in EXACTLY(EXACTLY) the same order as it came apart.There is plenty of people that know how to do clutches.Hope this helps

VALVES need to be adjusted it propbably pops and back fires when running too

Yes.Hold the decom and give it 2-3 kicks.Release it and slowly kick it untill pressure builds up.Pull in the decom and move the kickstarter a very small amount to get the piston very close to t.d.c..Now,give it a full kick and at the same time release the decom.Hope this helps you

Sometimes they will hang between gears and cause this.Put it in 2nd and rock it back and forth.Hope this helps.Always check the easy stuff first