KDX Hard to Start

[Dangerfield]

I've got an '81 KDX420 that is dificult to crank from a cold start. Once its warm, it cranks on the first kick, and even the next day it will crank on the first kick. However, if it sets for longer than a couple of days, it is very hard to start. Nothing short of a light shot of ether or a pull-start will get it to crank. From my experience, this generally occurs when the engine is low on compression, but I recently rebuilt the top end, it has 150psi compression, and a new plug. These vintage 2-strokes can be ticky. I've built three or four over the last few years, but I'm not a seasoned 2-stroke guru. Any tips?

[2002shee]

I notice with the KDX450 that the choke lever pops up as soon as you try to kick it. Unless someone holds it the damn thing wont start. I would check out the carb first. 150 is plenty enough compression, they start hard below 100 and not at all around 85. Like you said these older bikes are tricky but worth it in my opinion!

[MX86]

question.. do you leave the gas on?

could be the carb.. or a bad petcock and needle and seet letting gas into the crank while it's not running...

[BlueDiablo]

I actually have the same carb on my Blaster. I know differant engine and all but all i did was give it a nice cleaning and actually had to bump the jetting up. Id take a lever choke over a pull one anyday. Not sure why but i like em better.