No ignition on cyl. 1 and 4 - TCI unit problem?

[Lynge]

My 78 XS1100 has suddenly become a 550 cc 2 cyl, low performance bike after no more than 180.000 km!

There is no spark on Cyl 1 and 4.

This is what has been testet:
Visual test for spark - ok cyl 2 and 3, not ok for cyl 1 and 4
Pickup resistance - both ok
Pickup output - both ok (app. 60 Hz at 2000 rpm)
Coils primary resistance - both ok
Coils secondary resistance - both ok
Ignition cables resistance - all ok
Voltage levels at TCI-unit - all ok accordingly to the shop manual
Voltage at ignition coil primary side - both ok

Coil swap - no change

Carburetors and gas supply - ok

Compession - all 4 cyl. ok

I have the feeling that i am looking at a new or repaired TCI-unit, but other (cheaper) suggestions are very welcome.

The condition came about very suddenly, as typically for electrical errors, not like fuel supple errors, or mechanical errors due to wear normally do. I am certain that the problem is electrical.

From previous threads i have see thar others have repaired the unit successfully (Randy for one). So - does anyone have any clues to how I can test the TCI-unit for errors, and suggesions to parts that are likely candidates to cause the problems I experience.

It is summer in Denmark and I need to get the XS1100 rolling again

[dfrooney]

just to close the loop on your testing...

- swap your spark plugs to the known good #2 and #3 cylinders to make sure they are good. It would be weird to have 2 of them go at the same time, but it's worth a shot.

- check the plug wire caps for proper resitance (this may be included in the coil checks...I don't remember)

I think you covered everything else.

[Lynge]

Hi Dan

I forgot - I have tried to swap the spark plugs - no change

I still think that I have to open the TCI-unit - hopefully It is just a vibration related problem, and not a IC-problem

Thanks.

Jan Lynge

[DEmily]

If you have already tested the coil, I would check the pickup coils for breaks in the wires. I had the exact same problem and found a broken wire on the pickup for 1 and 4. But that was not all of my problems. Randy finally talked me into openning up the tci and resoldering the solder joints. Everything is working great now. Appearently the broken pickup coils wires are more common than the loose solder joints, but both are issues that you face with this bike.


Good luck!

[eltoroloco]

Just how do you check the resistance on the ingition coil wires?

[DEmily]

Go to the FAQs on this site. You will find the subject listed there.

[randy]

Lynge,

Here is your definitive test of the TCI. This test will identify cold solder joints.

Do not remove the TCI from the bike.

Remove the small screws from the cover, exposing the circuit board.

Start the engine and keep it running by raising the idle speed screw.

While running, gently tap the circuit board with the plastic handle of a small technicians size screwdiver. Do not use anything conductive.

Tap in various locations.

When 1-4 fire up, there is where your cold solder joint is.

Shut the engine down.

Using a small 20-25 watt soldering iron and a thin gage 60/40 rosin core solder, heat and re-solder the suspect joint.

If this test does not work, then you have a component failure that cannot be diagnosed in this forum.

HTH,

Randy

[Lynge]

Thanks guys

I em pretty confident that I have no broken wires in the pick-up cirquits as the resistense is ok, the frequence reading is as expected, and the problem is 100% constantly there.

I will however try tre "on machine" test that Randy suggests. The problem has been there (at least it has felt so), but now it is there constantly, and i don't expect faulty transisters to act like that, whereas a bad connection might do just that.

I am still confident that i wont cost a bundle to get the old faitfull XS1100 back in good helth.

Jan Lynge

1978 XS1100

[Lynge]

new problems

Hi

Still working on the problem - Randys tip didn.t find any loose connections, so I assume that some component has broken down.

This brings me to another problem. How do I get the boar out of the TCI-unit. I can see two srews on the outside and one on the inside, but it feels as if the whole ting is fixed by more than thes. Is it the spades for the external connectors or?

Any tips as to hoe w´the thing is taken apart?


Jan Lynge

1978 XS1100

[randy]

Do you have a plan for troubleshooting on the individual component level? If not, then don't bother removing the board.

If so, to remove the board has to be de-soldered from the connectors. Use a solder sucker and a low wattage iron. If you've never done this before, it's a slow process. Take care, go slow and avoid overheating the copper traces on the board so they don't disintegrate.

HTH

Randy

[Lynge]

Taking the TCI unit apart

Thanks Randy, I'm onto it right now.


Jan Lynge

1978 xs1100

[raqumup]

i will tell you what i had with my 79 xs11 special. i would ride it for a little while and all of a sudden i would loose half the engine, only running on two cylinders, for a littel while i could pull in the clutch and goose the throttle and it would go away, but i really got anoying and it cut out completely. so i decided to find the problem. it took me a couple of weeks to find it but insde the igniter box (that black computer under the seat) there are two trasistors, one for each ignition coil. one of those went bad and would randomly cut out on me. the way i found it was i had to cut the black plastic case off of the module and trace the circuit board, desoldered the one that went to the coil that would stop working i got one from radio shack (NOT THE RIGHT ONE) and put it in and the bike did run on all four cylinders, not well, but all did run so i knew that the igniter box would fix it so i got one from a junk yard $100 (dealer $400) and have not had a problem sence. not saying this is your problem but this happend to me
Troy

[pgg]

Lynge, I'd spend an hour or so and strip down the whole centrifugal mechanism for a check.

[Lynge]

Which transistor

OK - testing shows that one of the big transistor has passad on. The excistings are of type ETD32-035A which is not available today.

Does anyone have a suggestion to a replacement (Randy?)

Appreciate your assistance :-)

---------------------------
Jan H Lynge
jan@xs1100.dk

1978 XS1100

[randy]

Yes, I have used Motorola 2N3055 in the past and it's worked fine. If you don't have access to it in Denmark, I'll send you one. Before you replace it, find out why it fried or you'll wind up frying the new one, too.

Some things that will fry the outputs are:

-Shorted primary in the coil.

-Dead short to ground on the coil primary wiring, the orange or grey.

-Running a stock coil without the ballast resistor for an extended period of time.

Check these things before replacing the output just to make sure.

HTH

Randy