MX 250A Carburettor Specs

[PCMAX]

Can anyone advise what the standard main / pilot jets, float level, needle, needle jet are for the '74 MX250A

[Stewart Allen]

Use the same as where in the scooter you were riding last week, they'll work a treat.

[PCMAX]

Use the same as where in the scooter you were riding last week, they'll work a treat.

Nah not sure that the Honda Vario runs a Mikuni Stewart, not even sure it has a carby!!
I will get it sorted one way or another and see you on the start line at Canowindra this weekend. The weather is looking great, just need to disable Holmseys water truck 

[Stewart Allen]

Sounds good, been a while between drinks for me hope I remember how it all goes.

[shelpi]

Ive had a peek at Yamaha 250's everything except MX250 but if the carby is around the VM28mm on average it is as follows
mj 150 - 160
pilot 50  remember average + or minus 10
float level 19 - 22 +or - 2.5
jet needle  5d to 5f
needle jet O-4 +or -
sorry only ball park figures but will get you going, start rich oh yer get yourself the Sudco mikuni 5th edition tuning manual its cheap its the bible and you will luv yourself for doing it 

[Viper79]

I have checked the Yamaha parts listing at work.
It should be..

Pilot 50
Main 260
Air jet 2.0      in the back of the intake bell
Needle jet  P5
Needle  6F5

[shelpi]

onya Viper now ya right in the money.... but seriously get the Sudco Tuning Manual as in I mean anyone and everyone that doing any level carburation should have it

[Nathan S]

There were two different sizes of carb fitted to MX250s. Early ones had 28 or 30mm (?), later ones had 34mm.

[Iain Cameron]

73 and 74 ran 30 mm and the 75 ran a 38
250 73\74 main 250 ,air #2.0 , nozzle p-5, throttle cut #2.5 , needle 6f5-3 ,pilot #60 .
250 75      main #380  , nozzle P-4 , throttle 3.0 , needle 6f16-2 , pilot #60 .

[jimg1au]

looking at my gen yamaha mx manual as i type
ltmx vm26sc
atmx vm26sc
mx250 vm30sc  mj 250 jn 6f5-3 nj p-5 ca2.5 bp 1.8 po 0.8 pj 60 as 1.0 v.s 3.3 sj 80
 for a mj260 jn 6f15 nj p-8 pj 50 ca3.0 flot level 23.4mm
mx360 vm34sc
sc500 vm38sc

[BETRIC]

73 MX250 = VM30MM CARB
74 MX250A = VM34 MM CARB SAME

[PCMAX]

Thanks for all the replies, it was getting a bit confusing as I have a VM34 carby which is standard for the '74 model so I eventually found the OEM details. I have posted them below for anyone's future reference.