Horsepower ratings

[madmax-im]

It has been well known that the 1978 and 1979 model year XS1100s came from the factory rated at 95 hp. But as the model years progressed the hp ratings dropped off until we get to 1982 XJ1100 at approx 79hp.especially with the YICS system robbing hp for cleaner emissions...Is this correct? This is what i rememeber from past discussions..I cannot find anything in the archives to adrress the question...and all the online sources say the 1982 XJ100 Maxim had 95hp..I am certain this is incorrect..Can someone verify this ? or am i dreaming? I am having a discussion with a 650 forum member who has acquired an XJ1100 maxim...

[cajun31]

It has been well known that the 1978 and 1979 model year XS1100s came from the factory rated at 95 hp. But as the model years progressed the hp ratings dropped off until we get to 1982 XJ1100 at approx 79hp.especially with the YICS system robbing hp for cleaner emissions...Is this correct? This is what i rememeber from past discussions..I cannot find anything in the archives to adrress the question...and all the online sources say the 1982 XJ100 Maxim had 95hp..I am certain this is incorrect..Can someone verify this ? or am i dreaming? I am having a discussion with a 650 forum member who has acquired an XJ1100 maxim...

I think all xs1100's as well as the xj1100 had 95 hp. It was the same engine and the yics only made it more difficult to tune the carbs. You had to have the YICS carb tool to accomplish that. We had or have a member that actually made and sold that tool and most just put it in the carbs to basically eliminate the tuning issue.

[madmax-im]

I had an XJ 1100 for 30 years there's no way it was 95 horsepower the YICS system detuned the engine. I also had the YICS eliminator
tool made by Yahman.

[madmax-im]

Both TC and Jerry mentioned that the YICS engines were detuned from the original 95 hp..Neither one mentions specifically the hp ratings but it is clear it was not 95 as all the internet sources say...
http://www.xs11.com/forum/showthread.php?t=21283

[madmax-im]

Also...

#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. __________________ Life is what happens while your planning everything else! When your work speaks for itself, don't interrupt. 81 XS1100 Special - Humpty Dumpty 80 XS1100 Special - Project Resurrection Previously owned 93 GSX600F 80 XS1100 Special - Ruby 81 XS1100 Special 81 CB750 C 80 CB750 C 78 XS750

[bikerphil]

Don't forget, the 95 HP was measured at the crankshaft. By the time it went thru the two drive train 90 degree bends, you would be lucky if you had 79 HP at the rear wheel, probably more like 65-70.