Does anyone know of a screw adjustments for the old trx350 carb, i dont see any but i remember honda motorcycles sometimes had a round plug covering a screw adjustment, my old 86 V500 had one
for altitude (i guess it was a air or mixture adjust screw).
The 350 runs to rich even after cleaning the carb, it sputters in low gear unless your under a load.

 

I don't know what you consider to be the old Trx350? If you mean the 00-03 Rancher 350s the mixture screw is on the bottom of the carb. If you are referring to the 86-89 TRX350, it is also on the bottom, if I'm not mistaken.

 

Its a 89 - trx350d and i cant find any adjustment screw on the bottom, just the bowl drain screw and
the throttle idle adjust screw with a black **** that mounted on the side of the carb.

 

Take a look at this:
http://servicehonda.com/hard%20parts/atv/trx350d%20%2786-89%27/trx350_(d)_1986-1989.htm
Maybe it will help. Also, if necessary, try asking on Highlifter's Forum. There's a number of guys on there with the old 350s.
Pat