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ac10
03-24-2016, 09:21 AM
85 Big Red 250 does the choke plunger control air or fuel.....seems to me that the small shaft at the end of plunger is just a guide........since Iam having a cold start issue researched this problem........the starting jet is a 2 step design..large end is 2mm and the small end is .8mm. Someone said to try drilling the jet larger so drilled to .9mm. There was small improvement but cant seem to get the fast idle....carb is clean..Thanks for any info...

dougspcs
03-24-2016, 08:19 PM
When the plunger raises it allows fuel to pour directly into the carb Venturi.

So to directly answer the question it controls fuel.

There is an old Honda service bulletin about drilling out the jet where the needle seats to correct cold start issues.

Flyingw
03-25-2016, 02:58 AM
Everything you need to know about the cold start mod is in my tutorial. http://www.3wheelerworld.com/showthread.php/161746-ES-SX-350X-Carb-rebuild-Tutoral?p=1257154#post1257154

ironchop
03-25-2016, 10:50 AM
Awesome tutorial! That needs stickied somewhere convenient.

Sent from my Z998 using Tapatalk

ac10
03-25-2016, 02:45 PM
ok thanks so it is fuel

ac10
03-25-2016, 02:47 PM
thanks...great info