Praying for another easy fix....

[5th_bike]

Congratulations. Your prayer has been answered - you found the vacuum hose. It connects to a little nipple on top of the carb tube at the cylinder side, right where it connects to the rubber tube going to the cylinder.
It should have a little clip as well, to keep it on the little nipple. The way you have it (not connected) it will not allow gas to run down to the carb when the petcock is on "run" or "res". Only on "pri".

The way it works, when the engine is on, there is a vacuum in the carburator, which opens a valve in the petcock for the gas to flow.
When there is no connection - no vacuum to the petcock - valve stays closed - no gas to the carb.


You can read about the subject extensively in this recent thread (also has pictures and part numbers):
http://www.gz250bike.com/forum/viewtopic.php?f=4&t=6734

[apaz]

Yup. Just as I posted that, I went back outside, took the tank off and started checking tubes and wires (just for good measure) and noticed that little nipple and just figured that was it. I plugged them together and went for it. There was no little clip, so I think I'm going to go get a small clamp of some sort to keep it in place. Sure enough cranked up and stayed on.
I did notice that the exhaust pipes were super hot. I noticed that the oil was just a tad low and added just a little. There was some smoke coming from just under the fuel tank. I'm hoping that it's just some sort of left over something or other.

I'm attaching a picture of it.

Thanks again for all the advice.

[Goose51683]

Glad you found the answer.

I do a lot of troubleshooting at my job Andy saying is, 99% of the time it's something stupid, bad connection, disconnected hose, missing bolt etc. unfortunately these stupid little things seem to take forever to find