'78E, '79F,SF vs. '80G,LG,SG, '81H,LS,SH

[mixelpix]

Besides the different ranges on the speedos, what are the performance differences between the pre 80 and the later models?

I ask cause I definitely feel like my 80MNS doesn't want to go as fast as my '79SF (R.I.P. - resting in pieces...) will again one day.

They both have that vacuum advance assisted fell when rocketing up the gears, but in 5th w/WOT the '79 felt like it never wanted to stop. Maybe I need to re-synch the carbs, but the '80 just doesn't have that topped ripped off, no holds barred approach to the higher speeds.

Just curious if there is like, a governor of some sort in the electrical brain box or something in the circuitry? Maybe something mechanical or carbureated?

I'll go poke around the archives summore.

Thanks!
-pdk

[wildbill]

I don`t think this will answer your question but the older XS`s were quicker and faster. The newer ones seemed to be tuned down for some reason. Maybe in the timing or in the cams but there is a difference. Don`t think I answered your question but you are not alone in noticing this.

[Jerry]

Over the years Yamaha made a few changes in the engine. Lowered compression ratio to 9.0 - 1 from of 9.2 - 1, changed valve size (slightly larger in later engines) and changed carb jetting. The later model ('81, '82) switched from mechanical vacuum advance to electronic 'black boxes' that have the advance curve built in, also a change between the '81 to '82 black box. This had the effect, at least in the '82 XJ, of producing a different timing curve. The '82 XJ also has the YICS (balanced vaccum ports) system common on other Yamahas of the early '80s. Ignition system changed as well, which is why the coils are different between the early and late XS/XJ models. There are other differences, including the change from the stock 17 inch rear tire to a 16 inch rear tire during the '80 model run.

It is generally accepted that the '78 and '79 models are faster than later models, at least in stock form. Pressure was being brought by the government to reduce emissions, so many of the modifications were done with that requirement in mind.

[Pat Kelly]

My LG is quick and fast. My E is quicker and faster (even in touring mode).
My LG is bone-stock (engine-wise). My E has Jardines, K&N airfilter (re-jetted accordingly), and Dyna coils.

[xsivebiker]

Rear Tire Size

Jerry, my '80-G has the stock 17 in. dia. rear rim. I'm running a tire size of MT90B 17 in a Dunlop.
Could it be that Yamaha went to the 16 in. rear tire in '81? Do some '80 models have 16 in. rear rims while other '80 models have the 17 in. rear rims? 'Just wondering.
Ride Safe,
Greg
'80 XS1100-G "Christine"
'93 KLX650-C1

[Czekus21]

I believe I read somewhere in a previous thread that the 80 model and newer were tamed down a little bit in the name of emmissions. The 78 and 79 were the fastest model out of the box. They basically shared the same motor and drive train with minor changes to the cosmetics. The E and the F came with 17 in rear tires where the SF came with a 16. The difference in the testing ( back in the day ) was about two tenths of a second. This was on the 1/4 mile. There is a wealth of info available. Just gotta take the time ( and alot of it ) There are over 2000 sites, through Yahoo, devoted to the XS1100. Just type in Yamaha xs1100 in the search engine and click go. I've skimed over every one of them so I know it will take you the better part of a whole day. Also read the tests and reports in the General Info colume