04 B&W250 starting issue when cold - revisited

[partyhut]

Still having cold start issue.  idle nor pilot adj. helped. Neither did valve adj.  Did get a manual
 what the heck is an auto bystander, what does it do?  What about the carb. mounted heater?
manual tells how to test these but not a word about their function.  Help !  still very difficult
to start the first time each day in cold weather.
Tried a light bulb under the seat with motor cover open.   no help

[MotoRandy123]

Well the auto by starter is your automatic choke. It has a needle that allows more fuel when you
start then the wax inside melts and the needle moves to stop the extra fuel. If not working it would
make for problems in the cold. A carb heater would stop icing. When moist air increases pressure
(as in the constriction of a carb venturi) the air will get cold and cause frost to form in the carb thus
messing up the mixture. That's probably not the problem for cold start...

[partyhut]

Thanks Moto.  will test the auto bystarter.  Sounds like that could be the culprit.

[MotoRandy123]

Just take it out and apply 12v, after 2 - 3 minutes the needle should move.

[partyhut]

I'm not being a smart a--  just curious.  I can see the needle dropping and changing the mix when the wax softens.  How does it get pulled back up for the next cold start? This is a totally new concept to me.  Why does Kymco not use a conventional butterfly choke??

[MotoRandy123]

Not sure how it works, just that wax melting is involved. They probably need it to be automatic
so you don't leave the choke on and pollute more than necessary. 

[partyhut]

that's understandable   I'll check to see if the needle valve retracted any at some point after applied voltage removed.  I suppose either condition could cause problems.    thanks !

[KymcoBW250Fan]

Wax increases in size as it melts (as opposed to water) so it would make sense that a small cylinder filled with wax would cause a small piston to be pushed out as it heats up, and that piston would be connected to the needle. When you turn the motor off long enough for the wax to solidify, it would then contract and pull the needle back to the starting position. Presumably there's a coil wrapped around the wax cylinder that causes the heat to melt the wax.

The way I have tested it before on my old Vitality is to connect a small tube to the channel that lets the additional fuel pass through (with the autobystarter in place), and blow. If you can blow air through, the autobystarter is open. Then, connect the autobystarter to 12 v for a few minutes, and if you can still blow air through the hose, it is not working properly.

It doesn't sound to me like the autobystarter is the problem though, if you could actually see the needle move, but doing the blow test may be a way to see if there's a blockage in the channel.