This discussion says the XJ engine was detuned due to EPA emissions..Scroll down to TC and Jerry's comments...No way was it 95 hp...but they dont say what the actual hp rating was...
http://www.xs11.com/forum/showthread.php?t=21283
and further discussion...
#9
10-31-2013, 10:52 PM |
| DGXSER
Doctor of XSology(Deceased) | | Join Date: Nov 2008
Location: Cincinnati, Ohio
Posts: 9,769 |
|
The transmission and its gearing is identical. The engine is very very similar. Not sure of compression numbers, but then almost every year of the XS engine had slightly different numbers for overall performance. Different cams, different pistons in 80-81, timing changes. Etc..
The biggest difference from the XS series engines to the XJ was the YICS system. The XJ has the YICS which basically is a way to equalize engine vacuum across all four cylinders. The biggest hassle is the need to block off the ports to properly synch the carbs. Most folks by the YICS eliminator and leave it installed permanently. Eliminating the YICS system.
The engine will bolt straight up into an XS frame, the same carbs, exhaust, U-joint, etc will all bolt right up. The XJ has an oil level light instead of an oil pressure switch. IT also has the clutch and side stand safety switches.
The XJ uses a vacuum sensor to signal the TCI of engine vacuum and the vac advance is built into the TCI. So you will want to pull the timing assembly off your F engine and put it in the XJ, so it continues to place nice with your TCI. The XJ being a one year model those TCI are harder to come by.
From a performance reference, the F was a stronger engine than the XJ. more powerful timing setup, stronger cams, head, piston combo. The 80's models got detuned a little for EPA purposes. However, I still believe that most of us will never use the full capabilities of these machines enough to notice.
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81 XS1100 Special - Humpty Dumpty
80 XS1100 Special - Project Resurrection
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93 GSX600F
80 XS1100 Special - Ruby
81 XS1100 Special
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Interesting, but not sure it's true.
Just for grins tried to pin this down,
the various "specs pages" claim the 95hp for the XJ but the only XJ11
Yamaha brochure I found didn't list HP, torque is 65ftlbs
"The biggest difference from the XS series engines to the XJ was the YICS system. The XJ has the YICS which basically is a way to equalize engine vacuum across all four cylinders."
This part isn't correct, while it does equalize, it's purpose, like similar Honda and Suzuki systems, was a way to improve combustion and efficiency at mid (cruising ) RPM.
Same with the vacuum advance, Like marty sez the XS11 wasn't noted for fuel efficiency.
Couldn't find any period magazine tests for the maxim 11 with 1/4 times. By 82 this was old tech. The XJ11 Prolly was best described as a way to eke a bit more product out of the driveline production tooling by making "special" styling changes.
Mains jets did go down from 115 to 112.5
Pilots actually went up from 42.5 to 47.5, though the carbs were changed in other ways, so???
cam is the same 79 on
3H5-12171-01-00 CAMSHAFT 1
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Yamaha Motorcycle 1982 XJ1100J
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Yamaha Motorcycle 1979 XS1100SF
pistons; 80 on are the same
crankshaft; same all years.
'Sposed to quit raining later, guess it will get a seat O' gggGary's pants" dyno run. LOL
Shifting is another matter, it takes some work on throttle, clutch, shift timing to get smooth shifts when honking it, tests noted "notchy" shifting as being an issue also. That's a big heavy crank etc. I did find shifting improved after some saddle time got the hands/foot timing adjusted/coordinated.
I'm not so much for top end runs, usually back off after about 100MPH though on later model big HP bikes have um "exceeded" that number, "just a little". LOL