richer main jets on stock XS1100LG

[DGXSER]

Like Richard outlined, the first letter denotes if was a variation of the base model.

The L models are the Midnight Specials

The S models are the Specials

IF no prefix, it is the "base" or Standard model.

The second letter denotes the year of the bike. Starts with

E for the 78,

F for the 79,

G for the 80 and

H for the 81.

I believe they started with E as it was the E model of the XS750, the 1100's little brother that it was based off of.

In 82 they made some major modifications to the overall bike and produced the XJ series. A one year model in the USA, ran until 84 in Canada and other places. The XS and the XJ share most all of the drive line components, but the cosmetics are almost 100% different.

[Bonz]

Thank you much! Makes sense, I should have figured that out.

[3Phase]

Well, son of a gun, sounds like Yamaha was using stuff out of the parts bin to make our bikes ....

Sort of, but not really. There are a lot of standard, interchangeable parts across most of the carburetor models but they are usually stored in trays, not bins. Aside from an early batch of BS34 III carburetors that required rubber plugs in the pilot jet wells, the major differences between the Standard and Special carburetors are the jet needles and the main jets.

There are at least three different jet needles for the BS34 III carburetors used in the XS1100 in the US and Canada, four if you count the jet needles used with the two different needle jets in the '78/'79 BS34 II carburetors.

BS34 II
1978-79 All = 5GZ6, inner pair X2-266 jets; outer pair X2-301 jets

1980 G = 5IZ7, X2-300 jets
1980 SG/LG = 5GL16, X2-300 jets

1981 H = 5IZ7 but just as likely to be 5GL16, X2-300 jets

1981 SH/LH = 5GL16 needles, X2-300 jets

1982 J = possibly 5GL16, X2-300 jets

1980/81 Canadian models = 5GLZ18, X2-300 jets


Off the top of my head I don't remember what jet needles were used for models sold in Europe but I strongly suspect that jet needles for models sold in Oceania are specially ground to match antipodean main jets with their holes drilled and threads tapped for counter-clockwise fuel flow.

[crazy steve]

Mechanically, the only real 'odd-ball' in the XS series was the LH Midnight Special. While the LG was pretty much just a Special with black/gold cosmetics, the LH actually had a number of different parts; the first appearance of the 'swirly' wheels, different calipers (which were 'linked' F/R), and different front forks. These parts were actually a 'preview' of the XJ, as they carried over onto that model when it came out.