I havent had chance to pull the carb out yet. Im going to check it to the manual with a rule then do the clear tube and see how they correspond. I will report back once its done.
I can see light at the end of the tunnel There is nothing worse than taking a bike out and not feeling confident it will start.
Thanks for your input chaps.

 

I assume this is done with the petcock Off. If tipping the bike over is a too-heavy proposition, just open the float bowl drain.

My float bowl drain screw's allen hole had been all but stripped out by its' previous owner(s). I just hack sawed a slot thru the center to be able to open/close it with a screw driver.

 

The tipping of the bike is done with the petcock open, I believe the idea is to tip the carb and float over sideways to allow a little bit more fuel to flow into the float bowl, which is what OP is doing by adjusting the float.

I don't really understand how draining the float bowl would help? Perhaps you could explain the reasoning on that one to me? I could see that helping if the bike was failing to start because it was flooding.

 

Right...I guess I wandered off the OPs reason for adjusting his float



I've drained some fuel out of the float bowl twice in the last 7 days I think it is, after accidentally flooding the engine while trying to start it.

Typically you can just shut off the petcock and crank it until it cleans out the excess fuel, but my battery would put up with excessive cranking

Both times lowering the fuel level in the float bowl by draining with petcock off has resulted in the bike firing right up.


I might want to adjust my float level to something a tad less fuel and see what happens

 

I guess water in the float bowl, or bad fuel would be reasons to drain the float bowl too, but in the case of my son's bike it just seems to be not getting enough fuel to start.

 

Got my carb out today. I did the clear tube level which showed the fuel level about 1 mm below the join between float bowl and carb. Once apart the float was measured at 16 mm which is 1 mm less than the manual start position.
I have now set it to 15mm so it will be interesting to see if this makes a difference.
I too was sceptical about this but it does kind if make sense that the fuel level produces a head of pressure. If the pressure is too low it's likely the amount if fuel available in the enricher circuit is reduced. Who know!! Let's see

 

Those are good observations about fuel level and cold starting, but I can verify that it's not always the cause of hard cold starting in this bike. I'm probably the one who has pushed for accurately checking the fuel level with a clear tube method more than anyone else. I'm also the one who came up with drilling the starter jet. I say this to indicate that the cold starting on my KLX was not fixed by adjusting the fuel level up to the max...1mm above the fuel bowl line. Mine was hard to start cold until I drilled the starter jet. But note...not every bike has the same exact issues even though there are some general patterns. Still, checking and adjusting the fuel level by the clear tube method is something that should be done before any other jetting or troubleshooting occurs.

 

Fitted the carb last night. Went to it this morning full choke no throttle and it fired on second crank. Too early to say its fixed but the signs are promising.
Its interesting that to get the fuel level to the top of the float bowl I needed to set the float at 15mm.
I agree TNC that opening up the starter jet is also likely to help. What diameter did you open it out to?

I'm going to run with this for a while and see if it has really helped or if it was a happy coincidence. Also it doesnt get really cold here for long so for the best part of the year its summer maybe I will get away with it. Lets see

 

The starter jet drilling is usually .018" drill bit. I forget what the guide number is for that size. Maybe someone else can kick that in.

 

I drain a bit of fuel out of the carb and the bike starts right up. I think it is the fresh fuel flowing in that makes it fire up. Seems like the gas now days ain't got no pop to it. I started doing this with a Honda CR 500. And after a few bump~starts with the KLX I do it quite often now.