UK Monster Owners Club Forum - View Single Post - raising needle in carb found wrong jets ?? weird

jerry · 11-09-2019, 06:08 PM

this is weird delving into the poor low speed running of Bilbos ex M750 i found some anomalies in the carbs

OK according to parts book a 1997 Monster 750 should have

main jet 132.5
main air jet .70
pilot jet 42.5
needle jet Y4
jet needle 5C-J1 4th notch from top out of 6

what the BIKE actually has is

Main jet 128 ????????? clearly not correct !!!!!!!!!!
main air jet .70 correct
pilot jet 42.5 correct
needle jet unknown not gone that far yet
jet needle unknown no markings 3rd notch from top out of 6 & 1mm shim under

clearly something very amiss ??? 128 main jet cant be right even M600 had 132.5

bike defo running lean ,, could it be someone tried restricting it for learner ?? or are the jets from a M400 ??????

also where on needle might i find markings i have looked under a microscope and nought to see????

trying to decide what to do bike now has factory cans and airbox and filter back on

should i get some 132.5 main jets and then raise the needle a bit ?
i have some 140 jets and Sils and open air box etc could try them ??

your opinions please

11-09-2019, 06:08 PM	#1
jerry Old Git Join Date: May 2006 Location: Cricklade Bike: Multiple Monsters Posts: 2,816	New M750, in carb found wrong jets ?? weird this is weird delving into the poor low speed running of Bilbos ex M750 i found some anomalies in the carbs OK according to parts book a 1997 Monster 750 should have main jet 132.5 main air jet .70 pilot jet 42.5 needle jet Y4 jet needle 5C-J1 4th notch from top out of 6 what the BIKE actually has is Main jet 128 ????????? clearly not correct !!!!!!!!!! main air jet .70 correct pilot jet 42.5 correct needle jet unknown not gone that far yet jet needle unknown no markings 3rd notch from top out of 6 & 1mm shim under clearly something very amiss ??? 128 main jet cant be right even M600 had 132.5 bike defo running lean ,, could it be someone tried restricting it for learner ?? or are the jets from a M400 ?????? also where on needle might i find markings i have looked under a microscope and nought to see???? trying to decide what to do bike now has factory cans and airbox and filter back on should i get some 132.5 main jets and then raise the needle a bit ? i have some 140 jets and Sils and open air box etc could try them ?? your opinions please __________________ MONSTERMAN Last edited by jerry; 11-09-2019 at 07:15 PM..