Difference between 1979 and 1980 XS1100.

[timoteo539]

I would really like to know what parts are compatible and which parts are not between these years. It looks like I am going to end up with a bike from both years. Both are Specials.

[MaximPhil]

I would really like to know what parts are compatible and which parts are not between these years. It looks like I am going to end up with a bike from both years. Both are Specials.

Hi timotreo,
Welcome to XS11. Your question is so broad most will not try to answer it. As you will have both bikes you will probably be one of the best people to actually answer this. I give you the task: Record your findings.
For specific parts a picture is worth a thousand word.
Many parts are interchangeable some are very specific by year.
I presume you are going to resurrect atleast one of them to ride.
Phil

[timoteo539]

Phil,
I think I can resurrect both. The '79 already runs well but needs the dremel tool clutch repair. The '80 is in better condition but the motor is frozen. It just sat too long I think. It only has 22K miles on it. One of my questions is I was wondering if the motor is shot in the '80, can I insert the '79 in it? The 80's have a kickstart prep, but no kicker. Will a '79 fit it? The plastic side covers are not interchangeable. How much other stuff is not interchangeable? The '80 has a Kerker exhaust system. will it fit the '79?
Thanks
Tim

[crazy steve]

Most of your answers will be found here... http://www.xs11.com/forum/forumdisplay.php?f=78
... but the bottom line is some parts will interchange, some will with mods, some won't. To hit the high spots, the frames/seats/sidecovers/rear fenders are different and won't interchange without major mods, there's major differences in the head/cams/pistons in the motors, and minor differences in the wiring/ignition systems. You can swap assemblies as a general rule (like motors, wheels, exhaust), but need to pay attention if using individual parts. The '79 Special is a one-year-only model and has a number of peculiar parts/features not found on other versions of the XS. The '79 motor is the hotter of the two; the 80-up motors were detuned quite a bit because of emissions.

One thing to note; Yamaha used two different carb banks on these. The '78-79 were one type, the '80-81 another. You can swap the entire bank, but don't mix parts or jet sizes between them. Jetting follows the year of the carbs, not the motor.

[MaximPhil]

Phil,
I think I can resurrect both. The '79 already runs but needs the dremel tool clutch repair. The '80 is in better condition but the motor is frozen. It just sat too long I think. It only has 22K miles on it. One of my questions is I was wondering if the motor is shot in the '80, can I insert the '79 in it?
Thanks
Tim

Hi Tim,
Many Frankenbikes on this forum. Our term for those made up from different years parts. Testing the limits of my knowledge now
You should be Ok to move the whole motor with it's carb bank. I think ignition may have some difference so ask that question .
Phil

[crazy steve]

...You should be Ok to move the whole motor with it's carb bank. I think ignition may have some difference so ask that question .
Phil

The TCI box is the same through '80, so no issues there. There is a difference between the '79 and '80 advance units so those should stay on their respective motors. A complete motor swap between these years is plug-and-play...

[TopCatGr58]

Ps, just to comment on the FROZEN engine. It doesn't have a kickstart to use to try to turn it. The large square nut fitting on the LEFT SIDE timing plate and the Timing plate is NOT very strong, so would NOT advice trying to rotate it with that, but instead to use the RIGHT SIDE Rotor fastening bolt with a HEX head bolt. These engines spin backwards=CCW when viewed from the RIGHT SIDE, CW when viewed from the LEFT SIDE. The Right Rotor bolt is on there with ~50 footpounds of torque, but could still come LOOSE if you try to rotate it CCW in an attempt to break the engine free. With the Spark plugs OUT, it will spin easier.

Next, get some Mystery Marvel Oil, and pour a few ounces down inside each spark plug hole, and let it sit overnight or two. The Engine can be turned the other way..CW with the Rotor bolt so you wouldn't have to worry about loosening. But folks will say instead to put the bike in 2nd or higher gear and then ROCK the bike back and forth to try to get it to break loose. OR...you could find a piece of wood/dowel that you could stick down a spark plug hole and hit with a hammer to try to knock a piston loose. If there's considerable rust, you may run the risk of breaking a piston ring? Others may say you should just pull the HEAD off and then you can better see how the innards look, the pistons, the cylinder walls of the other cylinders that are in the lower/down position and just how much rust, how severe.

We have seen reports of folks unfreezing slightly stuck rusted engines, start out with low compression, but after running the engines, and using a little MMO in the oil as well, unsticks the rings, and then they reseat and scrub the cylinders, and they end up with fully functional engines ready to put many 10's of k miles on them! YMMV! Good Luck.

T.C.

[timoteo539]

Thanks to all for the info.
Tim

[mikubuilder]

frozen motor

I got a 79F last year for parts(no title) with frozen motor...it's been sitting outside without spark plugs for God knows how long...long story short, topped up spark plug holes with Mystery Oil and ATF/Acetone mixture, 2 hrs later started rocking the wheel, and it broke loose. If you do it like that, make sure you've got rags all over those spark plug holes, other wise you might have that mixture on a ceiling....DAMHIK

[wjw11teen]

there is a product called KROIL..its from the kano labratories

google it and you will find it..this stuff is absolutely amazing for freeing rusted things

its spendy but worth every penny IMO...good luck

[jetmechmarty]

Before you take it apart

Try this!

How to make a spark plug into a "Greaseplug"

As long as you can get the valves closed on one cylinder, this will work.