greetings:

I have a 1986 honda 250 big red. The machine has been running poorly so I removed the carb. and installed a new carb. kit. The machine idles perfect, but when I hit the throttle it cuts out. When I was trying to adjust the pilot screw I noticed if you turned the screw all the way in or all the way out the engine rpm did not change at all in either direction. You could turn it all the way in and the engine still kept on idling. I'm not sure but I believe to adjust the pilot screw you warm up the engine to operating temp. and from a seated position back the screw out 2 1/4 turns then turn the screw in until the engine stalls, then turn back out 1 turn. Any ideas? I sincerely appreciate anyone's help. Thanks...

 

ya motor has to be at running temps so let it warm up then you will notice it will change im not sure from when you turn it in all the way how many turns out i havent done any carb work on any big red but the 185 i did it was 1 1/2 turns out

 

I have exact same problem wth my 1986 honda 250ES big red. The motor idles perfect, but when I hit the throttle it cuts out. I have cleaned and rebuilt the Carb (float and float valve, choke valve). Compression is 180 psi with no leakage. I put a new plug in it and I noticed that after just a short period of run time (5 minutes) it is black on the end and smell like gas. Issue has been progressive. For last couple of years I have had to run with choke slighly on. Appears to have good spark but have not checked the timing. Any idea's?