Hi all….I could do with some knowledgeable help please. I have an USA DT175 B ( according to the vin No. ). I’ve dismantled the Mikuni carburetor and have…….. 
Jet needle 5G4 with the clip on the third notch.
Main Jet 215-02 
Are these correct ? 
Many thanks

 from near Salisbury, UK.

Here is the first page of the parts list from the CMSNL site. There is likely a full service manual in the Tech Library (see top toolbar).

yamaha-dt175-1975-usaservice-data-pg1_bigyau1081servic_bcc6.gif (963×1500)

It's important to verify all the calibrated components, not just a couple of them.

5G4-3 is correct for the slide needle (the -3 means 3rd groove from top)

O-2 is the original needle jet size

Main jet screws into the jet holder in the side of the bowl at bottom of the needle jet and should be a 160

Pilot (idle) jet is a 25, located in well in the carb body

Throttle slide should be stamped with a 2.0 which is the cutaway spec.

All of the above should have the Mikuni "square within the corner of a square" trademark symbol stamped near the size.  Aftermarket parts like slide needled and jets sometimes are stamped with the same sizes, but are not the same calibration as original Mikuni parts.

Also Tim, I'm not sure what part number you sent me in a PM...  but if you are looking for the small o-ring 214-14147-00 that seals the needle jet into the well in the float bowl it should be an industry standard 007.  It's mentioned in many threads.

yamaha-enduros.com/index.php/forums/74-7...tter?start=10#147977

I think I'm late to the party & curious to know if you're chasing a problem in particular. Carburetor symptom problems are often caused by restricted exhausts on two strokes. Just thought I throw that in. Cheers from nz.