'79 & '80 XS11 Similar?

[sheeres]

I have a chance to pick up a 1979 XS1100 parts bike pretty cheap. I have a 1980 XS1100 Special. Are the bikes similar enough to warrant the purchase?

Thanks

[TopCatGr58]

Hey Sheeres,

You didnt' say whether the79 was a Special or Standard? The engine components are almost all identical. The ignition timing plate is different, but the TCI is the same. The regular differences between standards and specials are still there. The plastic side covers mount differently. The carbs are considerably different.
Hope this helps!?
T.C.

[MAXIMAN]

The heads are different. They'll interchange but the 80 has larger valves than the 79.

The cams are different. Again they'll interchange but the cams on a 79 are bit "hotter" (higher lift...longer duration) than the 80.

I'm not sure but I think the carbs are slightly different. Again they will swap in wholesale fashion but I'm not sure what indivdual parts from the '79 carbs will match the '80 carbs.

[pggg]

The larger valves dont neccasarily mean 'more power' as the smaller valves give faster flow but less volume, more torque in theory but it all gets tricky because cams, timing, carbs are involved too. With mixed 79 80 parts there's all sorts of variations to try, cams, carbs, timing, centrifugal units - all added up there's dozens of seperate combinations especially if you delve into mixing part combinations on combinations of component combinations where each combination of combinations has a differing combination. The good thing is most 79 -80 combinations do combine. End result is bugger all difference.