Is it impossible to start an air cooled 510 4 stroke

Has any one ever started a 510 easily, I receved my 510 imported from the USA and just had to put it together so to have a go , well first I checked I had a good spark, cleaned out the carb and jets,made sure that there was no air leaks between head and carb,still no start ,so removed the head and re cut the seats , got up this morning feeling really confidant I could just hear it roar into life with but just a couple of kicks, no didn't happen, changed ignition plug etc etc still no go, I do know a bit about engines so the cam timing ign timing is ok, the only thing I havent yet tried is towing with a car , but thats not how it should be, I read in the dirt bike test from the day that they started well they must have as they tested them. Got to be ignition , plug not sparking in the cylinder WHAT DO YOU THINK, someone help as my right leg is getting so big from kicking I am running out of trousers, or pants for the USA guys. ( its not all that bad as my trusty 430 is second kick just after the husky kick back)

Sold ! LOL !

Have you checked the flywheel interior even if there is good spark ?
I've also had this problem.
Is the flywheel hardly screwed ? Did it move ?

so it has or does not have spark?
if it does have spark
set air mixture screw at 1.5
turn idle control screw in a so its fast idle
kick it once or twice with choke on then turn choke off there should be some action

they bump start easily in second gear but make sure its over TDC , then you set idle mixture etc.

I always turn my idle up to start it

My 510s start easily, hot or cold.
Timing needs to be spot on and valves seal properly. Carb perfectly tuned, floatlevel correct, needle and emulsion tube perfect etc.
I dont use the auto decompressor and have them removed but use lever decompressor, make sure your decompressor has clearance in unused position thus no leaking xhaust valve.

Turn idle mixture (its a fuel mixture screw, airscrews are situared behind the throttle slide like Mikuni) and idle screws as per SA63.

Throttle wide open, decomp in, Kick over 3 times. Choke on, without decomp find TDC where engine rocks. Decomp on, throttle closed, and hoof it quick and hard. It should fire straight away.

all the above and also cam chain, I chased mine (86) for a while until I replaced the cam chain

Thanks for all the information, I now have a new confidence that it is going to run today,
Will let you know later

1991 san diego, my 1986 510TX (Air cooled) after lots of trial and error and new cam chain, this thing was a 1 kick starter. And was a very fast machine for the time.
Had to add on note---- JT Dalmation print gear,,,,,man that stuff was the cool look!! Helmet was a match for my KDX200

Yes it is .

still not many if any at all new bikes made that would beat the aircooled 510 in a all out drag race.

have a look in the single cam section on dellorto starting for the 610.. all applies to the 510

I found standard jetting to be the best for the dellorto -

60 start jet
52 pilot
170 main, needle and needle jet stock (cant remember what they are off hand)

Horay, its a fairy story ending , It runs 1st or second kick hot or cold, after towing it there was no signs of starting not even a back fire, And there we go in UK language what a prat I am, having only ever worked on 2 stroke huskys I put the position of the cover with the coils in the same position as the 2 strokes with the cable going up the front tube, I then decided to check the timing and noticed the hole in the front cover for strobing was a third out , moved it back and hey presto brum brum marvolous. Didnt ride it much but your right its going to be fast. Thanks for the advice, and they lived hapily ever after.

Arrf !!!

woo hoo a happy ending!!