Overview of the 38mm-Vergaser to the XS650

In expenditure for September 2003 "653", the club newspaper Netherlands XS club, is a detailed article over the different carburetor versions of the XS650.
By January Smit I translated and published this article here into German.

This was initiated by a Forumsthread

Part numbers

Yamaha assigned for the coding of the left carburetors the ET number 14901, the right carburetors with 14902 was designated. The schwimmerkammer has the number 14931. The model codes for these numbers vary. They begin with 256 and end with 2F0.

256

The first series of carburetors for the XS1, the XS1B and XS1F were not accurately alike always. The XS1 has a deviating nozzle needle (4JN15 instead of 4JN19) and a deviating leerlaufduese (45 opposite 42,5 with the XS1B and XS1F). The XS1F has another butterfly valve (type 125 opposite the XS1B also and/or. 120).

The carburetors are to be recognized clearly. The Choke mechanism sits at the left side of both carburetors and a curved metal strip connects the two mechanisms.

The schwimmerkammer with the number 256-14932 is completely different than all other schwimmerkammern of the 38mm-Vergaser: because the Chokehebel sits left, also the Chokeanreicherung is left at the schwimmerkammer. Those moved with the later types on the right side. The seals of the schwimmerkammern are for all 38mm-Vergaser equivalent, likewise the floats. To it the fig. 1-7 belong (of a XS1F).



306/366

With the transition to the XS2 to 1972 the carburetors changed for type identifier 306. The Chokemechanismus was only at the left carburetor on the right side, grew also in the dimensions in the comparison to of 256 and with a hose to the right carburetor was connected now. Thus also the connection changed to the schwimmerkammer. And the lever was modified in form and execution.

The handles, which fix the two gas courses on the diaphragm covers, were differently bent more briefly and. Also the gashebel were changed and the torsion spring behind it was strengthened in the comparison to the 256-Modell. With the 366 for the European market also the carburetor 366 was introduced, identically to 306, but to main jet 120 in place of the 130er.

In July 1974 also the signature "SOLEX" disappeared from the diaphragm cover. That was the only change at this diaphragm cover, which is identical over the entire 38mm-Vergaserpalette otherwise. (fig. 8. 15).



447

Into 1974, with the model change to the TX650A and following XS650A and B, then the type of carburetor 447 came. The most important change concerned the housing, which differs outwardly not from 306, a change at the flow channel (Venturi) has. With 306 (and also with 256) a clear narrowing was to be seen above and below the passage. The 447-Vergaser has these only at the top side in addition has it a connection for a negative pressure measuring instrument. The needle 4JN19 replaced by 4N08 and the leerlaufduese changed back on 45. Also the butterfly valve was again a 120er. The schwimmerkammer changed to that extent that the channel for the leerlaufduese is deeper. The gasoline stream remains as used by the main jet led.

533

When into 1975 the first 533 to the light came, the vergasergehaeuse were both on the right of and left modifies, since fastening spots were cast-on for the mounting of a connecting post. The connection came however only with that 584. Both on the right of and left the ueberlaufkanal was changed, otherwise there are no further differences to 447. Even the schwimmerkammer remained identical.

584/1E1

With model year 1976 the type of carburetor 584 appeared. There was not only now the lower connection of the two carburetors, but also the diaphragm covers got a connecting plate. A gas course was only attached, and both butterfly valves were connected by a bar with adjustment possibility. Also the Chokemechaniken was connected with a bar. The mold of the housing was modified only few. Only a drilling for the rest ball of the Chokehebels was additionally set. The small feather/spring was implemented mirror-wrongly in the comparison to the predecessor model (fig. 24).

The schwimmerkammer got the fourth form (fig. 25). The channel of the leerlaufduese was shortened again on the length of the 306 and the air drilling to the leerlaufduese runs differently. The main jet was 122.5, the nadelduese changed from Z-6 to Z-8 and the needle from 4N08 to 4M1. the leerlaufduese became 25 and also the starting nozzle changed. The Chokemechanismus, which served 306 only the left carburetor since that, was now responsible for both. Finally with the change on only a gas course also the torsion spring behind the gashebel was again changed. On it came briefly the outwardly identical 1E1, which contained however a main jet 177.5. (fig. 21. 25).



2F0

The last version of the 38mm-Vergasers was starting from 1978 the 2F0. The most remarkable change concerned the negative pressure diaphragm with the Nadelaufhaengug (fig. 27). The feather/spring was shorter.

The main jet grew from 117,5 to 135, the leerlaufduese of 25 to 27,5. The nadelduese became instead of Z-8 a Z-2 and the needle 502 in place of the 4M1. The modified Chokegehaeuse caused also a change of the tie bar. Naturally this had also effects on the schwimmerkammer, because thereby the ueberlaufkanal was omitted. (fig. 26, 27).

Carburetor Model	XS- Model	Year	Main nozzle	Needle nozzle	Needle/ Notch	Leerl. - nozzle	Umdr. back	Throttle folds
256	256-XS1	1970	130	Z-6	4JN15 3	45	1	120
	256-XS1B	1970	130	Z-6	4JN19 4	42,5	1	120
	256-XS1F	1971	130	Z-6	4JN19 4	42,5	0,5	125
306	306 Europe: 14908/ 14909	1971	130 140	Z-6	4JN19 4	42,5	0,75	125
366	366 476	1973 1974	120	Z-6	4JN19 4	42,5	0,75	125
447	447-TX650A	1974	127,5	Z-6	4N08 4	45	0,75	120
	447-XS650A/B	1974	120	Z-6	4N08 4	45	0,75	120
533	533-XS650B (Europe)	1975	120	Z-6	4N08 4	45	0,75	120
?	1E5 (policy)	1975/ 1977	120/ 112,5	Z-6	4N08 4	45	0,75	120
584	584, 1T3	1976-1979	122,5	Z-8	4M1 3	25	1,25	120
1E1	1E1, 1H1, 1U3, 1V2	1976-1981	117,5	Z-8	4M1 3	25	1,25	120
2F0	2F0, 2G6, 2M0, 2M1, 2Y8, 3N0, 3N1	1978-1979	135	Z-2	502 3	27,5	2,25	120