1979 frame 1980 engine

[jtab]

Will a 1980 XS11 SG engine fit easily on to a 1979 XS1100 SF frame? Or is there alot of mods that have to be made?

Cheers

Jtab

[Renegade]

It should be a bolt-in. You may encounter minor things like having to route wiring/hoses/cables a bit differently, but the engines are the same.

[dabien310]

HOw about the carbs? I have carbs from a 79 and 80 special. Would they be interchangeable?

Jon

[bkr]

Engine Swap

Should be a slip in ,carbs are the same ,jets may be different. bkr

[John]

Bolt it in and ride it away!!
ANY XS 11 or XJ 11 engine will fit in ANY XS/XJ frame. You would need to change the ignition, and alternator assembly to make it work in an XJ. I was running an XJ engine in my 80SG for many years before I did my big bore job. As far as carbs go, you can install a bank of 79 carbs on any XS/XJ engine and the same for the 80 carbs, but I wouldn't mix them up on the rack and try to make them work together. To many internal differences. It could be done, but IMO it would be a royal PITA to get them jetted and tweaked properly. Just remember that the older carbs have vent hoses that must not be blocked off! They must attach to the ports on the air box, providing they are open, or vented to atmosphere, and have small filters in them.

[dabien310]

Re: Engine Swap

If I choose to put the '80 carbs onto the '79 engine, will I need to rejet? Why different jet sizes if same carbs?

Jon

Originally posted by bkr
Should be a slip in ,carbs are the same ,jets may be different. bkr

[dabien310]

John,

I couldn't quite understand what you were saying regarding the statement below.... could you clarify? What does mixing them on the rack mean?

"As far as carbs go, you can install a bank of 79 carbs on any XS/XJ engine and the same for the 80 carbs, but I wouldn't mix them up on the rack and try to make them work together."

Sorry for the dumb question.

Jon

[John]

The main jet sizes were changed in 80 from 137.5 to a mix of 115's and 120's. The staggered jetting is to help cool #3 & 4 cylinders. Also the pilot circuit which is similar to an idle circuit used to get it's fuel through the main jet, but in the later carbs, the pilot circuit had a seperate pilot jet and therefore the mains were derceased. I meant that I wouldn't try to run a mix of older and newer carbs on the same engine at the same time. The older carbs needed external bowl vents to the airbox, and the newer ones didn't. Just too many potential headaches The rack that I refer to is just the rails that all the carbs are attached to.

[dabien310]

Thanks! That makes a lot more sense.

Jon

[jtab]

thanks that makes my life easier.

[Snow]

I've got an 80 or 81 motor in my 79, currently with 80 or 81 special carbs. Like stated in another post, any XS11 set of carbs should work on any XS11 - just don't go putting different year jets into the carbs and make sure they are all the same year in your set.