Help if you can, or trip is cancelled...

[DGXSER]

Hmmmm....Are you SURE you pulled the ballast resistor out when you put in the new coils?? This sounds way to much like it is still in there.

Wehn you first hit the starter, the ignition system bypasses the ballast resistor, when you let the bike run without it, the resistor comes back in. Strong initial spark then weak on 3 ohm coils, perhaps the ballast resistor?

As to the timing light, I have not seen one yet that would plain nto start and run at least crappy with the timing as close as the work to date would have it. I've actually yet to put a timing light on one, but mine are both 81 models anyway.

[CA]

Well I ordered a timing light, from the suggestion of psycho, and it was supposed to be here on Friday and I have yet to see it. But like DGSXER said, if it won't start then what the hey.

I remember back in my youth....(a number of months ago) I switched the plug wires all over the place and it was running like crap...but it would still run. Even if the timing is out of wack. which the timing plate does not show. Shouldnt the bike at least start stumble and cough and run like a HD??

That's what is wierd. My plugs are wet with gas. I can see spark. I have compression and the crude timing checks work out.

And yes i am 100% positive i took off the ballast resistor. Unless that thing I took off was an auxilary gas gauge (that is what I used to think it was!) I am looking at it in my parts box. But the funny thing is, it was still hard to start when I put on the new coils with the ballast removed. It always took more cranking than with the old coils. The old coils fired to life right away, (until the bike exhibited these same problems.) And as the week after rolled along it progressivley got harder to start. It would even do that wierd blow back moaning noise when trying to start, but eventually it would. Finally on the last ride it decided it had enough.

I have a can of contact cleaner I am going to drench the contacts with. The main ones to do are at the tci correct? Any other important areas that would affect this? ( I know all electrical connections are important but I just want it running.)


The only saving grace right now is I can still ride my brothers "new" 79sf and remember the glory days. But I want mine back!!!

[psycoreefer]

Have you tried new plugs? I'm just thowing this out there as really, we're all guessing at this point but here is my resoning,
You only have 5v at the coils = weak spark
Your battery was low = weaker spark
Inside the cylinder the atmosphere is denser = even weaker spark
Plugs are wet from all the cranking = even weaker then ^ that spark
Plugs have some carbon on them from running a few weeks = no spark at all.

Maybe all these little things are building up and each one seems to check out but when you add them all up they cause a no or eratic spark condition. Fixing any one might let it start, and the easiest and cheapest is new plugs IMHO.

Couple other things...
Contact cleaner probably isn't going to cut it, you'll need to either remove the connectors from the plugs one at a time and clean them with some sort of wire brush, or find something you can fit inside the plugs to scrub the connectors.

I'd do all the ones at the TCI, the ones at the coils, the ones going to the ignition switch, and any others you see along the way.

Something you could try, run a temporary jumper wire from the battery directly to the coils '+' terminal (thats the one that splits and hooks to both coils), and try cranking to see if it starts. If it does you'll know your fighting dirty connections or bad wires, I suspect that 5v just isn't enough to get a good spark.

Also, don't leave that wire in there, short term (like a few minutes while your testing) I don't think anything would be hurt but the guys at yamaha must have routed power for the coils through the TCI for some reason, I just don't know what it is. Maybe someone else will come along and let us know why?

[melbxs]

Follow these instructions to clean up all the important contact points:

http://www.benefiscal.co.uk/forum/in...p?topic=4234.0

[XSokieSPECIAL]

CA

This is a long shot but I had this problem with mine the other day after I washed it. It only did it when I put it in gear but it is possible under different circumstances it could couse a problem like your talking about.

Under the left side of the engine about halfway between the tip of the shift lever and the ignition cover is a wire connected to a switch with a single screw straight up from the bottom. This is the neutral light switch and it runs in the same harness as the wires for the pickup coils. The insulation on the wires in that harness can deteriorate and the neutral switch wire can short the pickups to ground.

Disconnect that wire and try starting the bike and see if that makes a difference.

Like I said....a long shot but what have you got to lose?

Sounds like an ignition problem all the way and those coils are the weakest point.

[randy]

originally posted by psycoreefer:

but the guys at yamaha must have routed power for the coils through the TCI for some reason, I just don't know what it is. Maybe someone else will come along and let us know why?

The TCI has a protection circuit in it that cuts off the coils if you leave the ignition on without running the engine, so the coils don't overheat. Here's the screen shot from the manual:

[psycoreefer]

well there you go, I learned something today, so you can run that jumper wire direct to the battery, just don't leave it hooked up if your not cranking the engine....

[CA]

Ok that is actually a really good idea. I will try it. I will be careful not to leave it plugged up.

I will also look into that neutral wire area as well. Thanks xsokie.

One of the first things I did when it caused me trouble was replace the plugs. Then after a whileI replaced them with my brothers which were a different brand.

I have pretty much switched everything on my bike except the coils themselves and the exhaust.

I have never been so perplexed. My big fear is I will wiggle something and it will work and I won't know why. I really need to pinpoint the issue so I can put it to rest. I may need to contact Nashville Bill see if he could swing by, yet I haven't seen him on the forums in some time.

[scalded dog]

If it was running and then started acting up, then the carbs should be fine, also, run in to a similar problem a couple times, one time found out the ignition switch had a loose wire, the other time had to fix the pick-ups a second time, the wire had come loose again on the inside of the rubber cover, also check the wire and fuse under the left side cover, that wire had gotten loose, made contact some times, and then not sometimes. also wires under the right side, behind the fuse box, sometimes starts getting lose, makes contact sometimes, and sometimes not. Wish you the best. Later 'Dog

[MindWebs]

not sure if this will help...

here is the service bullitins with a picture of the spark plug wire lay-out.

1979 XS1100SF Factory Service and Tech Bullitins.doc
http://www.megaupload.com/?d=A6T4FMMY

Good luck

Webs

[CA]

Ok. Its been awhile since I last posted but I still haven't figure it out! Just been busy. Wedding crashing Anyways last week we hot wired the coils and found that in fact it started pretty quickly. So its definately a power issue to the coils.

As we were trying to track it down my brother began to examine the tci and started playing with the burnt runner on my board. He pretty much broke the runner in two because it was already there, then we didn't have any power at the starter or coils. Notta. So either it seems we either inadvertently hit where the power suck was or it actually is the tci box.

The only way to rule out the tci box would be to take my brothers good one and put it on mine. I know we already did it the other way, but my way out hypothesis is that my damaged tci was providing enough power to my brothers bike to start and run because he has stock coils, yet on my with the mikes green ones it simply does not provide the needed juice. Therefore perhaps the tci is restricting the power?

Anyways I just need to find why the coils arent getting a full 12 volts instead of like 10.9. And now I especially need to find why I don't have any power to the starter or coils...lol.

Thanks, and happy fathers day to all you dads!

[psycoreefer]

Glad to hear your narrowing it down.

You can fix your TCI by soldering a wire from where that trace starts to where it ends. Done it plenty of times on pinball machines.

As for no power, your starter power doesn't go through the tci, check the basics, are you sure you didn't bump the kill switch? Fuses? Then start working your way along the wiring diagram.

[bikerphil]

If you search this site for \"full power ignition mod\", it will tell you how to have full voltage at the coils. I\'d search the link for you, but my proxy server won\'t let me. I run my 79F this way and it makes a noticable improvement.

[CA]

Here is the link for the full ignition power mod for future searches:

http://www.wgcarbs.com//index2.php?o...ge=0&Itemid=26

The only thing is I wouldn't mind doing this mod in the future, but I would find it prudent to find why mine has dropped so significantly before I jerry rig it.

I try following the wiring diagram but honestly it seems to just go in circles and has so many shoot offs I don't know what to follow. I hate electrical problems. I wish it was the carbs....

All that to say if anyone has some simple steps to finding the weakness I am all ears. I jsut don't know which connections to look at. I wouldn't suspect it is more than five I need to make sure are good.

[Ivan]

The easiest way to find a voltage drop is to measure it with a volt meter.

In this case, you'd start by putting one lead of the meter on the coil lug or connector of the power wire. The other lead back probing the TCI. If you only get 10.9V at the coil this should read very close to Battery voltage minus 10.9. If the battery is at 12.5v it should read 1.6 v. Now, this confirms there is an extra load in the power line, so its just a matter of finding it. So, move the lead nearest the coil back up the wire to the next connector aqnd back probe one side of it. If you still have the 1.6 (or what ever you get) then back probe the other side. Keep going back up the line until you hit a big fat 0V. when you see 0, then you know that is up stream from the extra load. Now, you can, if you like move that lead back to the previous place and start with the other lead and move down stream. Chances are you'll end up with the leads back probing either side of a connector with it saying 1.6v.

So, you say, what if I am at two opposite ends of a wire, and find the load is some where in the middle?

Well, there is the quick and dirty method of just running another piece of wire to bypass the bad part. splice it in and tape it up next to the main harness. It'll work just fine, but may put you in league with the dreaded evil PO at some point, because there is a wire that isn't in the harness and the guy you might have sold it to wouldn't understand.

If you don't want to join the ranks of the cursed POs, you can use straight pins to pierce the wire and check the load until you find it with in a couple inches. Get some clear (or pink, if that's your thing) nail polish and dab a bit over the holes left by the pins to keep down water intrusion. Once you find the load with in a few inches, you should see the problem. Usually its a place the wire was pierced and water got in it or a rubbed wire that only has a couple strands left.

Its fairly simple to do, but digging through wiring harnesses is a pain. Remember, you are looking for a 0V read on the wire. The coils should be the ONLY load on that circuit. They should use up the total 12v. Also, I think the TCI turns off the coils after a few seconds, so you may have to cycle the key at each test point.

Hope this helps.