OzVMX Forum

Marque Remarks => Yamaha => Topic started by: jimg1au on July 02, 2010, 10:54:31 am

Title: YAMAHA 1976 YZ125X CARB/JETTING
Post by: jimg1au on July 02, 2010, 10:54:31 am

bike almost ready to test run.factory carby 34mm with 310main i built a carby to factory specs all but 2.5 slide against 3.5 std.i have run 150mm of fuel throught it and it was very dead in response.the carby which came with the bike is a 32mm with 230 main.this is for dirt track only and a biger carby on a 250 or 400 is good.this is the very first 125 i have ever owned(naten talked me into it)so any help would be good.i am thinking it should be no different to my cz400 in how to jet but would like some proven jetting to help me get it right.
it starts and idles fine
jim

Title: Re: YAMAHA 1976 YZ125X CARB/JETTING
Post by: DJRacing on July 02, 2010, 08:41:32 pm

I run a standard carb in my YZ125X and it runs fine.

Title: Re: YAMAHA 1976 YZ125X CARB/JETTING
Post by: wmc83 on July 02, 2010, 08:49:32 pm

my 125j has a vm34 and its main jets only a 260 and I think thats to rich 310 sound way to big IMHO

Title: Re: YAMAHA 1976 YZ125X CARB/JETTING
Post by: jimg1au on July 06, 2010, 12:17:51 pm

any one else with a yz125 34mm carby know there jetting

Title: Re: YAMAHA 1976 YZ125X CARB/JETTING
Post by: mboddy on July 06, 2010, 08:23:09 pm

YZ125X standard carby is 34mm.
310 main
P-8 nozzle
6F15-2 needle
3.5 cutaway
60 pilot
2.0 air jet
80 starter jet
1.0 air screw turns out

Title: Re: YAMAHA 1976 YZ125X CARB/JETTING
Post by: jimg1au on July 06, 2010, 08:28:31 pm

thats what i have got but only 2.5 slide runs very rich.

Title: Re: YAMAHA 1976 YZ125X CARB/JETTING
Post by: mboddy on July 06, 2010, 08:33:59 pm

Just file 1mm off it and you will have a 3.5.

Title: Re: YAMAHA 1976 YZ125X CARB/JETTING
Post by: Freakshow on July 06, 2010, 09:17:22 pm

Less volume.... less margin of error