Ignition Question

[BROOKSIE]

Hello,
I'm brand new to the XS1100, I have a 1981 Midnight special. After riding it approx. 35 miles it fouls a plug, not allways on the same cylinder and all four plugs are shooty black.

first thing I did was check all electrical conectionsremoved and cleaned all the carburators and checked the float levels. new plugs and 35 miles later same thing. tried hotter plugs, same thing.

I checked the TCI and rersoldered the conections, checked the pick-up coil wires all good.

I then beat my head against the wall in rapid succession and took the bike to a mechanic friend of mine.
He found the pick up coils are acting Erratically (wires check again and still good)

The TCI is a 4RO and the mechanic thinks this is the wrong TCI because it has the ballist resistor to the coils and the vacume advance. I have only had the bike a month so it could have been replaced by the PO.

If the pick-up coils are bad wheres the best place to locate some? have called several places and have not found any other then for a 1979 and an 1980 are they the same?

I have found this site to be very helpful, thank you for any information or suggestions.

[John]

The 4R0 is the correct TCI for an 81 Midnite, but it should not have a ballast resistor, but it will have vacuum advance, but no mechanical advance. Try bypassing the resistor, because it is only supplying the coils with about 9 vols, and they require a full 12 volts. What is the VIN? That will help determine the vintage of the bike. The sooty plugs may be a sign of rich carbs or an air restriction, or a weak spark at the plugs. have you tested the coils and plug wire with an Ohmmeter? Make sure the air filter is clean, and the inlet snorkle is clear. Check the pick up coil wires where they are held in place by the clamp attached to the timing plate. That is a common area for breakage, and check them by lightly trying to stretch each wire. If you feel stretchage, and see an hourglass shape form in the insulation, then you have located the break. As far as locating new P/U coils I think Parts n More or Bike Bandit may have them. There are other members that have bought new ones, and maybe they'll chime in.

[BROOKSIE]

Vin# is 4H3000580, have checked and rechecked the the wire by pulling on them. also used ohm meter and could not find any problem.

carbs were cleaned and floats checked and there was no change in the sooty plugs. thats why we are stearing toward the ignition being weak. the balist resistor appears to be a factory mounted to the frame.

thanks...

[John]

The bike is an 80 Midnight Special according to the VIN and the 4R0 is the wrong TCI., and does require the resistor. The correct TCI has a 2H7 part number. That may cure all your ills.
Are the wheels straight or curved spokes? Do you know if it has a linked brake system, or does the front front master cylinder control both front brakes.
Look at the yellow margin of this page. See the sixth link that says Specifications? Click on it and look for serial numbers. There you will find the year of your bike. That's where I went.

[BROOKSIE]

well as luck would have it I just found out the bike is a 1980 not an 81 as I posted earlier, sorry.

I'll go back to banging my head against the wall.

[BROOKSIE]

Thanks John

Now for a search to find the right TCI

[John]

The 2H7 TCI is very easy to locate and is not expensive. The 4R0 is hard to find and can be expensive. Ebay has them all the time, and our member andreashweiss is a big time dealer.. in used parts that is. Contact him for any parts needs.