XS/XJ Engine Swap

[MBone]

First post to the forum!
Hoping someone might be willing to give me some much needed advice. I have an 80 XS1100SG. The motor is seized. I found an 81 XJ1100 that has a good motor without carbs for a decent price. The carbs from my 80 XS are in good shape.

Would this be a good choice for a replacement if I bought the YICS passage blocking rod? Will the carbs from the 80XS work with the 81XJ motor?

From what I've read the motors should interchange. Possibly some ignition issues? I'd like to be sure before I spend the money. I'd love to get my 80XS basket case running.

Many thanks in advance!
MBone

[red bandit]

Welcome to the site and the 11.
The carbs will work great. The engine will swap right in. You will have to put your 80 timing/ignition on the 81 motor. It will swap right in. BUY IT.

[motoman]

You'll also have to use the 4RO regulator module. The one on bike now will not allow timing advance(under left ignition cover) to work correctly, and as stated that whole ignition assembly has to be swapped from existing motor, THEN you can use the existing reg. module.

[MBone]

Red Bandit/Motoman,
Thanks for your advice. I think I understand what you are
Saying needs to come off the 80XS and on to the new 81XJ.

May have a couple follow up questions.
Thanks again!

[TopCatGr58]

Hey Mbone,

First of all, are you getting the entire bike minus the carbs?? Secondly, if it's truly an XJ1100/Maxim, and has the badges and YICS, then it's at least an 82 which is the year they started. However, they were MADE in 81, and sometimes PO's and DMV's make that mistake and mislable/register them with the wrong year indicated. If you can get the VIN# from it, it should say 10M-##### to be an XJ, but if it says 4RO, then it's an 81 Special.

If it IS an XJ11, then you have an opportunity to improve on the wonky slanted specials front brakes, because the Xj's front fork sliders use a different caliper design.

Also, the XJ's alternator is slightly stronger than the XS's, but I don't know if you would need to use a different Reg/Rect, 3Phase/Scott or Geezer would be able to tell you about that, or you just might need to swap some wires in the plugs.

T.C.

[BA80]

You'll also have to use the 4RO regulator module. The one on bike now will not allow timing advance(under left ignition cover) to work correctly, and as stated that whole ignition assembly has to be swapped from existing motor, THEN you can use the existing reg. module.

1) If he swaps the ignition and timing parts (left engine cover) from the 80 into the XJ engine (which BTW is an 82) the 2H7 ignition box will work as it is supposed to.

2) The Alternator parts (right engine cover) will need to be swapped too. XJ has a completely different alternator and aren't compatable with the SG charging system or wiring harness.

3) I suggest the YICS ports be blocked with the blocker tool so that a proper sync can be done. Most JJ owners just leave that in there because they seem to run better.

Other than those things, the XJ engine is exactly the same as the SG engine.

[BA80]

I posted that under the impression you wer swapping the XJ engine into the SG. Did I misunderstand?

[MBone]

Greg/TC,
Thank you for the help. Much needed and appreciated. Yes I am looking at putting the XJ engine in the XS. I will be getting the entire bike less carbs. I've rebuilt the carbs from the XS and will be putting them on the XJ. Will check the VIN# to confirm the actual year.

Thanks again!

[BA80]

Greg/TC,
Will check the VIN# to confirm the actual year.

The only year of the XJ in the US was 82, Canada had them for a few more years. It may say the production year on the sticker as 81 but the model year is 82.

First 3 of the VIN will be 10M.

[MBone]

Update:
I bought the XJ1100 for the motor. Got the complete bike less carbs. It is an 81 according to the sticker but the motor serial number is 10M so must be an 82.

Took the left side motor covers off to check out the ignition to prep for the ignition swap. Looks like I'll have to use an ez-out to get the mounting studs out of the 80 XS since there is no fastener heads. Can I use socket head cap screws as opposed to the special torque studs to remount on the XJ?

I can see where there is a rubber plug in the XJ to pull the vac tube through. Would you recommend cutting off the electrical connector to pull the points wires through the motor case?

My Clymer manual says I have to rotate the crank in the XS to get the ignition back plate off. My problem is the motor is seized. Is there a work around or should I be able to get it off the 80 XS without turning the crank.

I really appreciate any advice!
Thanks,
MBone

[3Phase]

Update:
I bought the XJ1100 for the motor. Got the complete bike less carbs. It is an 81 according to the sticker but the motor serial number is 10M so must be an 82.

Took the left side motor covers off to check out the ignition to prep for the ignition swap. Looks like I'll have to use an ez-out to get the mounting studs out of the 80 XS since there is no fastener heads. Can I use socket head cap screws as opposed to the special torque studs to remount on the XJ?

I can see where there is a rubber plug in the XJ to pull the vac tube through. Would you recommend cutting off the electrical connector to pull the points wires through the motor case?

My Clymer manual says I have to rotate the crank in the XS to get the ignition back plate off. My problem is the motor is seized. Is there a work around or should I be able to get it off the 80 XS without turning the crank.

I really appreciate any advice!
Thanks,
MBone

Hello, MBone, welcome to the forums!

The 'special' screws were an emissions anti-tamper thing to keep people from changing the timing. The bolts are no longer available so you can use any bolts you want, a couple of SS Allen bolts with washers make it easier to adjust the timing and won't rust.

The rubber plug does have to be removed from the XJ engine so you can connect the vacuum advance but what page in the Clymer's manual are you looking at that says to turn the crank?

You don't have to turn the crank to take off the timing wheel, vacuum advance, mechanical advance, or the pick-up coils and timing plate from your '80G engine after you drill out and remove the bolts.

Everything will bolt right onto the XJ engine but I'm not sure what connector you're talking about cutting off to run wires through the case. The pick-up coil wires should have a small rubber half-round grommet on them that fits a matching notch in the case and the timing cover holds it in place after its bolted on, then the wires just run along the lower left side of the engine to the Neutral Switch, around the back and up to the wiring harness connector behind the fuse box mounting plate.

Here's a factory service manual link. It's for the '78E but the engines and ignitions are all the same from '78 to '80:-

[URL=https://1drv.ms/b/s!AlA_igDQ6LzjgsFav4aS_EVp6mV-oQ]
XS1100ServiceManual.pdf[URL]

[BA80]

I think the manual says to turn the crank so the reluctor will line up with the slot in the breaker plate. However, the plate can be turned once the screws are removed to get the reluctor through

[3Phase]

I think the manual says to turn the crank so the reluctor will line up with the slot in the breaker plate. However, the plate can be turned once the screws are removed to get the reluctor through

Thanks, Greg, that sort of makes sense but the reluctor and mechanical advance come right off the engine along with the pick-up coils when you remove the bolt for the timing wheel. Manuals.... (sigh)

Edit: I messed up the link to the fine manual last night.


XS1100ServiceManual.pdf

[BA80]

Thanks, Greg, that sort of makes sense but the reluctor and mechanical advance come right off the engine along with the pick-up coils when you remove the bolt for the timing wheel. Manuals.... (sigh)

Edit: I messed up the link to the fine manual last night.


XS1100ServiceManual.pdf

Yeah, I know but that's why they say that to remove the breaker plate. It all will need to be changed over though.