HELP switching from points to electronic

[imanightsurfer]

Hi all, I'm hoping someone can tell me if I'm going to have any headaches switching from points to electonic ing. or will it bolt right on? I'm taking my eng. off my xj1100 to but a big bore kit in and I've got a good eng on my xs but the carbs are no good and I dont want to spend any money if I don't have to so Im going to have to use the carbs off my xj which dosn't have the same vacum advance as the other and allready has been jetted to my pods and exshalt so is there anything I need to know before tieing into this would be helpfull. Thanks

[JACKHAMMER01]

Well surfer, I would say the biggest thing to keep in mind, while attempting to remove the points and convert to electronic inition, on both the XS and The XJ motors, is that they both already HAVE electronic ignitions.

[imanightsurfer]

then why do I have a vacum advance I aint opened it up but if Ive got vacum adv. Ive got to have points and the hosing is bigger but ill go open it up right now and find out I may be wrong. But thanks for the input

[psycoreefer]

your wrong...

The reason you've got a vacume advance is that the "curve" isn't built into the earlier TCI boxes, on the later ones it is.

So if you want to rid yourself of the advance take all the parts, including the TCI box and everything under that left cover from the newer bikes motor and transfer it to the older bike's motor.

[imanightsurfer]

Ok i stand corrected so how do i just use what I've got. Can i hook the vac. adv. to one of the places on the boots is that the same as on the carbs?

And agin thanks

[psycoreefer]

not sure what your trying to do. Are you putting the XJ motor in the xs frame? The other way? Just the XJ carbs on the XS?

If your just switching the carbs then you could leave the vacuum advance disconnected. There are a few around here doing that. It is only used to improve economy while at part throttle cruising. If you want to hook it up you can hook it to the synch port on the boot but you will have to put some sort of restriction in the line to keep the vacuum from "pulsing" with the intake stroke. I've read that an old pilot jet will work but I've never tried it. To be sure it's working leave the cover off and watch the plate as the motorcycle is running if you see it pulsing back and forth thats bad, it should be steady and only move if you open or close the throttle.

[imanightsurfer]

What Im doing is Ive got an xj11 that I love and I found an xs11 in a old barn that had been sitting since 1989 of course with the gas in it but has less 13,000 miles on it I started restoreing it but would'nt you know it on my xj the timing chain is starting to make some noise and second gear is doing it's thing so I figure I've got a almost new motor on the xs why not just put it on the xj so i can keep riding. And finish restoring the xs and go ahead and fix my xj hopefully with a big bore kit so this way I'm not without a bike for the rest of the summer.
Thanks for the input and advice.

[TopCatGr58]

Hey NightSurfer,

To make using the XJ's electrics when swapping the XS motor to it, you will want to swap the Ignition parts...the stuff that bolts onto the left engine crank assembly...the timing plate, etc. using the stuff on the XJ engine, and removing the mechanical cent. and vac. advance parts off of the XS engine. Also, remove the ALT parts....the rotor and ALT cover and windings assembly, again putting the XJ's parts on the XS's shaft. You may even want to swap the Oil Pans so you will still have the OIL LEVEL sensor to connect to. You won't be using the Oil Pressure sender unit that's on the top back portion of the XS engine just in front of the starter.

As has been suggested, when using a mech. vacuum adv. unit connected to the intake ports, putting a restriction in the line like a pilot jet will work. HOWEVER, the XJ doesn't use a mech. vac. adv., but has a little black box that a vacuum line from the main vac. system ports connects to...not to the carbs. So...keeping/swapping the XJ ignition parts onto the XS engine will allow you to use the XJ carbs without worry about the mech. vac. adv. unit connection!

Good Luck with the swap!
T.C.

[imanightsurfer]

Thankyou T.C. been a while since I've been on here hope everything is good at your end. Hopefully this swap is only for a short period of time (rest of summer) which way would you go? switch everything or just put a resricter in line.
thanks

[TopCatGr58]

Hey Night Surfer,

It's not just a matter of using a restrictor with the XS engine and it's vac. adv.!! The XS engine has mechanical cent. adv. and WILL cause increased timing advance in addition to the timing curve that is ALREADY programmed into the XJ's TCI, not a good mix! And I'm not sure about the ability to plug in the XS's TCI into the Xj's harness, so that's why I suggested swapping the XJ's ignition triggering parts onto the XS, so that you can use the XJ's ignition system without having the older XS parts causing problems it!
T.C.

[yamahansolo]

this thread is interesting. just one question for the xperts????

if i were to swap my xj parts to my 79 xs would this give me any better economy of power at all?

also it looks like someone may have grinded on the plate inside the cover and maybe advanced it a little? or it came from yamaha that way?
i can post pics later???
thanks!!!

[TopCatGr58]

Hey Chris,

I just reviewed the ignition module thread from many months ago, and it showed the XJ's timing curve when under hard acceleration, low vacuum levels is actually slower, not reaching full advance until about 5.5K rpm, where as the mech. cent. adv. attains full advance at 4750 rpm!

IT does show a steeper quicker increase in advance when combining both higher levels of vacuum and cent. adv. curves, but it doesn't provide a direct comparison of the XS's combined curves vs. the Xj's??

SO....doubtful that it would really provide any noticeable difference in fuel economy using the XJ's vs. the XS!?
T.C.

[yamahansolo]

thanks for the info!!!!!

i was debating it trying to decide if it would be worth the swap when i put my zrx carbs on in a few weeks. i have to get the bike put back together now though, all my parts should be here next week!!!!!