fj tci

[GARTHXS]

Would a fj1100 tci work on an xs

[randy]

Garth,

Maybe yes, maybe no. i'm guessing that the FJ's have the advance built into the TCI just like the later XS's and XJ's. Someone here can verify that, like maybe Kat or Gareth. That being said, you'd need the boost sensor to make that work, or forget the boost sensor and use the XS mechanical advance. There is going to be a wiring issue also, I'm sure the pinout at the plugs is not the same.

[GARTHXS]

maybe xj

The reason I ask is my 78 has fjcarbs and I don't have a real way to get a vacuum to my advance so I am wondering if there is another way to make it work. So I was thinking. Maybe an xj or fj tci to eliminate the need for a vacuum advance

[DGXSER]

Hey Garth,

Yep the XJ did incorporate the vac advance into the TCI, however the H model XSes only incorporated the Mech advance into the TCI so they still use the vac advance. AND IIRC, the XJ also used the same 3 ohm coils as the H model XSes. Which means that unless you already have, you will need to change out the coils if I am not mistaken. and dump the ballast resistor. I am not 100% certain of all that, but I think I gleened that much from some of TC's post in the past.

[randy]

As far as the coils go, as long as you maintain a total of 3 ohms, it won't matter which set you use. The early set of 1.5 ohm coils / 1.5 ohm resistor will work equally as well as the later 3 ohm coil / no resistor set.

[GARTHXS]

advance?

So would I have to rewire to accomodate a xj tci and would I retro fit the advance or just leave my origanal in place?

[Guy_b_g]

Pick up an .030 or .035 MIG welding tip and insert it into the vacuum hose to the advance (cut the hose in two) then plug the hose into one of the four vacuum nipples on the intake manifolds. That'll damp the vacuum impulses enough to let your vacuum advance work properly.

[GARTHXS]

pulse

I thought because the vacuum is after the butterfly the pulse is too strong and intermittant to give a good vacuum signal

[Guy_b_g]

No, it'll work fine..just has to be damped with some restriction. AlanB or someone else who has done this may also want to chime in...anyway it's a lot simpler than plumbing in a new TCI. Try it.

[cywelchjr]

I thought one of the points of the fitting on the carb is that there is no vacuum at idle. I noticed when working on mine that the vacuum advance didn't see to do anything until I raised it up off idle.

Of course I could be wrong, but that is my recollection. I would think that the spot for the port is there on all the carbs, just plugged on the others, but then that could be wrong too.

[GARTHXS]

it is

I thought one of the points of the fitting on the carb is that there is no vacuum at idle. I noticed when working on mine that the vacuum advance didn't see to do anything until I raised it up off idle.

Of course I could be wrong, but that is my recollection. I would think that the spot for the port is there on all the carbs, just plugged on the others, but then that could be wrong too.

on the fj carbs the tower is there but I would have to drill it out then get another smaller drill and drill out the passage and finally grind a slot in the butterfly valve to give the port a gradual pull, I just dont have the tools to do that .

[Guy_b_g]

The vacuum advance port is a bit of a wild card.
there is no such port on FJ carbs so I am running off the intake boot.
At first when I tried this the vacuum modual would knock or click very hard at idle (at first i thought a valve was about to go)
Basically it was pulling WAY to much vacuum as the port on the XS carbs has a very small diameter.
I tried to replicate this with a small pilot jet inside the adavance line. All knocking or clicking gone and the ignition seems to advance properly.

Ben, I went to my local parts yard and went digging for the right cable, the FJ uses a push -pull cable (2 cables) but I went with just the pull. the cable stay on the carbs was the the crux of the job. I cut and re-welded the fj cable holder to work with my new cable. (higher than stock)
You MUST restrict the vacuum advance line. I used a small pilot jet inline (read this thread, i mention my tech early on), no restriction and the timing advance bangs itself very loudly.

ill post some pics tomorrow....
hope this helps.

The FJ carbs transformed my slug into a smooth running power machine. And with enough weight on the rear of the bike (my 110 pound wife) we get 3rd gear wheelies.

These posts are from this thread: http://www.xs11.com/forum/showthread.php?t=15648

Bfrehill did the same mod you are doing, used a manifold vacuum port. He used a small pilot jet (maybe from his old carbs?) as the restrictor.

[GARTHXS]

worth a try!

Why not, it can't hurt