The following table and descriptions outline the evolutionary changes to the carburetors used on all XS/TX 650 Yamahas.
All specs taken from the microfiche. All other
observations taken from carburetor body comparisons themselves. Changes are listed as the year changed. To find your
carburetors
start at the first year listed till you find something different than what
is listed then go to the next year listed. Keep following this till you
arrive at your year. If an item is listed as a change in a year it follows
through for all following years till noted again. | ||||||||||||||
| 1970 XS1 | 1971 XS1B | 1972 XS2 | 1973 TX650 | 1974 TX650A | 1975 XS650B | 1976 XS650C | 1977 XS650D | 1978 XS650E | 1979 XS650F | 1980 XS650G | 1981 XS650H | 1982 XS650J | 1983 XS650K | |
| Body Model # | 256-00 | 447-00 | 584-00 | 2F0-00 | 3G1-00 | 5V4-00 | ||||||||
| Body Part # | 306-14901/2-03-00 | 447-14901/2-00-00 | 584-12901/2-00-00 | 2F0-12901/2-00-00 | 3G1-12900-00-00 | 5V4-12900-00-00 | ||||||||
| Main Jet | 130 | 127.5 | 122.5 | 135 | 132.5 | |||||||||
| Air Jet | 1.2 | 1.0 | 1.0 | 1.0 | 1.0 | 1..0 | 1.0/1.4 | |||||||
| Needle Jet Size/Length to meeting of body from end | Z-6 12.5mm | Z-6 8mm | Z-8 8mm | Z-2 8mm | Y-0 | |||||||||
| Jet Needle-Clip Position | 4JN19-4 | 4N8-4 | 4M1-3 | 502-3 | 5HX12-Fixed | |||||||||
| Pilot Jet | 45 | 42.5 | 45 | 25 | 27.5 | 42.5 | ||||||||
| Pilot Screw | Type 1 | Type 2 | Type 3 | Type 4 | ||||||||||
| Pilot Screw Setting | 1 | .25 | 1.5 +/- .5 | |||||||||||
| Starter Jet | .6 | .7 | 1=80/2=.5 | |||||||||||
| Float Level | 25mm | 25mm +/- 1mm | 24mm +/- 1mm | 27.3 +/- .5mm | 22 +/- 1mm | |||||||||
| Butterfly | 125 | 120 | 135 | |||||||||||
XS1 (1970)
Bodies
 |
Yamaha Series 256
| Solex Bodies.
| Bottom of Venturi has raised floor
| #125 Butterfly plates.
| Throttle cable connectors are dual 2 finger style.
| Fuel crossover tube through 90 degree fittings.
| Choke assembly mounted to left side of carburetor body.
| Choke lift arm on left side of carburetor body.
| Choke assembly connected by a flat metal strap.
| Emulsion tube/Main Nozzle Z-6 and is 12.5mm long where it meets into the body
| Pilot Jet 45.0.
| Butterfly shafts have end caps.
| Bell housing (air box end) has 2 molded in orifices (non removable jets).
| Intake mounting - 47mm
| Type I pilot screw (brass, threaded head straight shank then a taper)
| Depression for overflow tube on carburetor body is 9.5mm deep from gasket surface
| Enrichening tube is on same side as the overflow tube recess. |
Float Bowls
|
Float bowl overflow hose connected to a plastic 90 degree nipple.
| Float bowl has enrichening circuit pickup tube on right when looking at it upright mounted on the carb.
| Enrichening tube pickup is on same side as the overflow tube.
| Enrichening tube protrudes 10mm above gasket surface on the float bowl. |
XS1B (1971)
|
Pilot Jet 42.5. |
XS2 (1972)
Bodies
|
Choke assembly mounted to right side of carburetor body.
| Choke valve capped off on right hand carburetor (#2). Choke for #2 is via a cross over tube
| Butterfly shafts no longer have end caps. |
Float Bowls
|
Enrichening tube moved opposite overflow tube
| Float bowl stamped "A" on bottom center.
| Will only fit on 72/3 models. |
TX650 (1973)
|
Throttle cable connectors are dual ring and barrel style. |
TX650A (1974)
Bodies
|
Mikuni Bodies
| Raised floor removed in venturi and has a round bottom there.
| Emulsion tube/Main Nozzle Z-6 and has been reduced to 8mm long where it meets into the body
| Yamaha Series 447
| #120 Butterfly plates
| Pilot Jet #45.0
| Depression for overflow tube on carburetor body is 6.5mm deep from gasket surface |
Float Bowls
|
Float bowl stamped "H" on bottom center.
| Will fit on 72/3 models but overflow system will not work as designed. But may work better? Since overflow is 3mm lower than previous years. |
XS650B (1975)
|
Identical to 1974 |
XS650C (1976)
Bodies
|
Yamaha Series 584
| Throttle cable connectors are single ring and barrel style.
| Carburetor synchronization assembly introduced.
| Carburetor synchronization access ports/screws added
| Reintroduced right carburetor choke assembly.
| Z-8 Emulsion Tube/Main Nozzle
| Type II pilot screw (same as type I but has a knurled head added to the top of it)
| Pilot Jet #25.0
| Enrichening tube protrudes 20mm above gasket surface on the float bowl. |
Float Bowls
|
Float bowl overflow hose connected to a brass nipple molded into bowl. |
XS650D (1977)
|
Float bowl overflow hose nipples removed. |
XS650E (1978)
Bodies
|
Yamaha Series 2F0
| Bell housing (air box end) has 4 molded in orifices (non removable jets).
| Z-2 Emulsion Tube/Main Nozzle
| Type III pilot screw (steel, with integrated o-ring on screw)
| Pilot Jet #27.5 |
Float Bowls
|
|
XS650F (1979)
|
Identical to 1978 |
XS650G (1980)
|
Yamaha Series 3G1 (3W6 for Australian Models)
| #135 Butterfly plates
| Pull knob choke assembly
| Chrome diaphragm covers
| Fuel tee instead of individual spigots.
| Removable main air jet from bell housing.
| Intake mounting - 42mm
| Top mounted pilot screw.
| Type IV pilot screw (brass, just like type one only longer with a smooth smaller diameter boss for the screwdriver slot).
| Pilot Jet #42.5 |
Float Bowls
|
Only a bowl. No jets at all in the bowl.
| Float bowls have side access drain screws.
| Float bowl nipples have no hose nipples for hoses but they do have drain bosses. |
XS650H (1981)
|
Identical to 1980 |
XS650J (1982)
|
Yamaha Series 5V4
| Black paint on bodies
| Steel brackets has black oxide coating
| Screws have black oxide coating
| Cable operated choke |
XS650K (1983)
|
Identical to 1982 |
If anyone has Australian model numbers or knows of variations that should be noted on this page, please let me know at xs650@xs650.org.au and if I can confirm this information I will include it.