Trouble shooting nightmare check here!!!

[Nastydude]

I'm back and i've still got the same problem with this 78 XS 1100. These are the symptoms: sputtering, kicking, backfiring, poping in the exaust. intermitant loss of cylenders. running lean, running rich Surging. here is a description of a typicle ride on my bike: start it fires quick it may run fine or it may run on less than four cylenders (by less i mean may be two or three it depends on luck). Than i start off in first it may run fine or it may pop backfire and sputter depends on luck. When i stop at an intersection it may idle fine or it might sputter kick running run on 4 3 or 2 cylenders depending on luck. when you try to go again. same thing as before. these symptoms are a roll of the dice but the do seem to lessen slightly when the engine is hot. best chance for decent operation is a very slow acceleration from idle to about 3500 rpm there is always symptoms between 3500 rpm to about 45 to about 5000 rpm. than it clears up and runs fine. During hard excelleration from idle to redline it will sputter kick backfire pop in the exaust to about 4500 then it starts to surge to 6000 rpm than it clears up and pulls hard to redline.

OK now that is a kind of idea of what I have been dealing with. now this it what i have tried to do to remedy the above mentioned problems none of which have had any effect either positive or negative.

My Friend, the guy I bought the bike from has an identical 78 xs 11 which runs very well so any parts changed were from his bike.

New plugs (no change), went through my carbs from top to bottom atleast 6 times (no change), switched carbs with my friend (no change) switched ignition module (no change), switched coils (no change), switched the entire vacuume advance and pickup assemby (no change). messed with the timing (no change) float levels have been set and checked numerous times (no change), when carbs are adjusted and synced the bike runs great but drive five feet or less or just shut it off and restart it and you are back to the same thing again (no change), and the timing chain has been adjusted (no change).

Any ideas other than dynomite.

[Winterhawk]

Sounds kinda like the ignition pickup wires. Gently try and stretch the wires at the advance unit. If they stretch they are broke or separates when it advances.

[TopCatGr58]

Hey Hawk,

He says he switched out the ENTIRE Pickup coil assembly, so I would "Assume" he meant the pickup coils, wires, and all!?

Okay, a few questions for ya NastyDude! Will it rev okay just sitting in neutral!?

Stupid ?, is the vacuum advance hose on the carb nipple(good) vs. the intake boot nipple(Bad)?

When you switched out the PU Coils, and other ignition parts, did you go back with the older parts, or did you just keep adding he swap parts, so that you ended up with his COILS, PU coils, and Igniter box?

Still sounds electrical to me, like a partially broken or worn thru insulation and intermittently grounding wire. Since it was still there with the swapped TCI, I would look very closely at the PU coil assembly again, as per Hawk stated. ALL of the connections in that circuit from PU coils to TCI!!
T.C.

[pgg]

Low rev vacuum problems in the fuel taps?

[Pat Kelly]

Try swapping gas tanks.

[Nastydude]

some times it reves goodin neutral and some times not. All of the wires have been checked or changed with the pu assembly we would change each part than at the end I put all of my parts back in. there was no point keeping any of these parts as his bike ran fineand none of the parts made a difference. fuel delivery is fine as the same symptoms persist with cocks on pri and I have checked the amount of fuel delivery from the cocks there is more than enough fuel to run the bike.

[pgg]

Dodgy plug caps or tension leads. They tend to come right at high revs - and play up even if a multimeter checks them as O.K.
Those dodgy plastic pin plug connecters also.

[Czekus21]

I would have to agree with the possibility of your problem being electical. On your pick-up coils. the wires feed under the middle drive, up to the brain box. Un plug the connector with only four wires. With a multimeter set for Ohms 1k, check your resistance between the connector for each coil. With the cover removed from the left side of the motor, move the advance unit by hand and see if there is a fluctuation in the Ohms reading. Do this test for each coil. while your doing the Ohms check is a good time to do the tug/pull test on each wire. Then you'll know, without a doubt if this is your problem.
Also double check that all of your wire connectors are tight throughout the entire electrical system,( including at the headlamp assy. ) With the intermittin problems you've discribed, these checks should pretty much let you know where the problem is let alone possibly fix it. Wish I was there to give you a hand.

[Nastydude]

i changed the entire pickup coils and advance assembly including the wires right to the plug connector behind the fuse box with a known good unit. the coils have been changed with known good coils the tci box has been changed with a known good unit all of the connectors associated with these devices have been repeatedly disconnected blown out and reconnected. there has never been a point where any of these operations had a positive effect. by intermitant i don't mean that i might get a good ride for a while because that is not the case. these symptoms are persistant with only an odd short window of kind of good operation like 1/2 a block or less. symptoms always occour on acceleration to some degree the faster the excelleration the greater the severity of the symptoms. there are always symptoms between 3500 to 4500-5000 rpm fast or slow excelleration. at a constant trottle below 3500 rpm it will at times show symptoms to the point that the bike will actually decellerate to a stall if i let it but slowly it just sputters kicks backfires pops and will die if i work the throttle gently down and up or open the throttle compleatly it will keep it going. and all of these symtoms are worse before engine reaches operating temp. is there any thing a box or a plug in the electrical system which is associated with producing engine spark that i have missed.

[srq68]

Did you try the parts you interchanged with your friend's bike on his bike to see how it ran? Maybe it can help in case a combination of 2 marginal parts is enough to create one problem...

[Nastydude]

no we didn't but we changed all of these parts before we put them back so even if there were two marginal parts on my bike. they were all from his bike and it still ran the exact same way.

[TopCatGr58]

Hey there again Nasty,

Well, as some one mentioned earlier, the only thing you didn't swap was the gastank, and even though the petcocks are flowing well, the quality of the fuel, water(which sinks!!) could be trapped in there, and since you tried the other carbs, although it had it's ?good? fuel at first in the bowls, after running for 5 minutes or so, you would/should have gone thru that and be getting into the gas tank's, and so it DID run poorly then as well!

Also, the intake mounts, what condition are they in, badly cracked? Have you checked for vacuum leaks, sprayed WD-40 or such around them while running to see/hear a difference in RPMs?

Also, what's you air filter like? Are you running Stock box, or Indy filters? Did you put the stock box back on with the borrowed carbs, or the Indy filters!?

Just thinking of anything else!? T.C.

[macnut xj]

This might be totally off the wall, but have you checked the connections at the fuse box for the ignition fuse? Maybe a poor connection at the fuse or on the back of the box might be causing the ignition to have low power intermittently. Or it could be a problem in the ignition switch or the emergency kill switch. Does your bike have the tip-over switch under the seat like my XJ?

[Czekus21]

Ya know, the more I think about this, the question keeps comming up, Have you pulled the petcocks out and checked the screens for the possibility of rust cloggings or other debris?
Also may check that vacume line that runs to the advance unit. I know you replaced it, But is the hose ran correctly? When accelerating the vacume advance should move, this may be pinching the line to where you won't be getting any vacume to the octopuss. That's something else you may want to checkas the octopuss is the blood giver for your motor. have you tried running with the gas cap open? clogged breather on a warm day pessure/vaccume not being able to breath, not a good recipie for running good, On the lighter side, you may spend $3.00 on a gremlin bell to ward off the evil gremlins that are taking up refuge in your ride
Just trying to feed some more ideas at you. You've probably tried all of this stuff but like I said in my last reply, " I wish I was there to give you a hand." Hopefully ya get er goin. Lots o luck and I'll keep rattlin my brain.

[skids]

I had problems like you described when my exhaust system was shot. I put on some fiberglass baffle type mufflers and the problems just shifted to different rpms. The insulators on the sparkplugs appreaed to be glazed and were hard to read. It burned to hot at some rpms and too rich at others. I went through the same diagnostics that you did until I slapped-on a stock exhaust system. Wierd!

Another thing to check is a stuck or sticking carb slide, bad kill switch, bad fuse connector. I woulld say to check the tank vent (run with the cap open), but it does not seem to be your problem.

Originally posted by Nastydude
no we didn't but we changed all of these parts before we put them back so even if there were two marginal parts on my bike. they were all from his bike and it still ran the exact same way.