non-firing cyl..

[motoman]

Hi all, I found non-firing plug problem,etc. I pulled all plugs, laid 'em against engine, and saw that #2 and #3 were not firing. The local accessory shop had a few 11's out back, so I bought both coils, and the ignition box, as it was an 81, also man.date of 7/80. Installed both those coils as the other(#1and#4) had a weak discolored spark. The bike started right up, and fired on all cyl.... Then I un-plugged from existing tci(which was for an 80 or earlier) and plugged in the 81 unit, and engine revved quicker. So all your input was well taken, and some of it applied. Now that I've solved that problem, next will be the engine swap, as the same place has a 78 which has good compression and 25,000 miles on it. Ill use my intake and carbs(after rebuilding them), as this has no carbs(just plastic baggies)on intake. That being the case, rather than change pick-up coils, I'll just use the earlier ignition box, and hope tranny is in pretty decent cond., and see what transpires. I figure for $200 dollars, and my time to remove the other engine, as they're letting me bring it home, and bring back what's left after removal.....figure it's worth a go. So if any of you can think of any glitches or things I need to look for or check without being too involved, let me know. My engine and tranny was really abused for all those years I did'nt own the bike, as compression while I had those plugs out was #1, 92psi and #4 at 125psi, and the rest between those two numbers, so it wasn't firing the fuel very well unless it was wound up above 4 grand, and won't even idle......so Thanks for all the good info that's here...proved to be verey useful..

[TopCatGr58]

Hey Motoman,

I haven't looked that closely at the pinouts for a comparison between the 78 and 81 TCI's? Not sure if any wires will need to be swapped in your wiring harness for using the 78TCI?

The 78 engine should be more peppy than your 81 model even if it was in good shape! You'll want to pull the valve shims from your 81 to be able to use for adjustment spares!

It's recommended to remove the oil filter cover to facilitate sliding the engines in and out of the frames. Suggested to take them in and out from the right side, so you're not pulling it passed the driveshaft area too much. You'll want to look closely at the engine rubber mounts, your 81 may be quite worn and compressed, and the newer 78 may be in better condition and provide better vibration damping!?

Wedging a hunk of wood in the rear wheel will help in breaking the U-joint bolts loose! Good luck!
T.C.

[motoman]

Thanks for all those tib-bits of info TC......it'll all be handier than handles on a basket......I'll need more than handles to pull that engine-tranny out tho.....hey, if I can R&R a Cat or Cummins, should be able to handle the XS? Thanks for the info on direction of removal....didn't really occur to me....makes sense tho...sounds like a fun thing to do this winter when it's ocasionally too cold to ride that other bike(honda st), and by this spring should have it all done, cosmetically also. Then I can stradle some old school power again. I think the ol' XS would give my ST a good run, at least for the first three gears anyway.....You have to know that I'm a gonna have to find that out too!.....just for s**ts & grins...What'cha think?

[rover]

Here is another tip. Remove the long bolt at the front that goes thru the engine, raise the engine up above where the bolt goes thru the ears on the engine, then slide the long bolt back in. Do the same at the rear, and the engine can slide out on the long bolts, and you only have to lift a bit to slide the ears over the frame, versus holding the engine up all the while you are moving it out the RIGHT side.