No spark 1990 3TB

[Hatrack]

Thanks. I'll try those .

[Hatrack]

That seemed to work better.
Using the 2000 ohm setting I got a steady reading of 245. Any good ?

[dzl]

yep thats in spec. Now the ignition coil. Have you replaced the spark plug?

[Hatrack]

Yes. Its a new plug and the bike was running Ok on it.
I have just tried resistance tests on the original coil, which showed no response on either terminal.
The replacement coil I realise has no + or - markings so O might have the orange and the red and white wires the wrong way around.
But I did get a reading from it measuring from earth to the spade terminal with orange wire connected, of 2.6 on a 200 ohm setting.
20K setting produced nothing, and the other spade terminal to earth produced nothing.
So maybe I have replaced a dead coil with a "cheap and nasty" or maybe incorrect coil.

[dzl]

you need to remove the wires from the lugs on the coil then put a meter lead on each of the coil lugs to get primary resistance. Specs say should be between 3.5 and 4.5.

To check the secondary coil, need one meter lead in the end of the spark plug lead on the metal part that touches the spark plug and the other lead to either of the coil lugs.

I just measured a known good spare genuine coil I have here and is showing 4 ohms on primary and 24K ohms on high tension lead so you may need to go up a one range on your meter to 200K setting to check the secondary as 24K ohms is too high for the 20K setting and wont give you a reading

[Hatrack]

Yep. That produced results !
Old coil:
Primary 4.7
Secondary 24.4

New coil (cheap aftermarket thing):
Primary 2.3
Secondary 17.2

So from that I geuss the new one is fit only for the bin. Is the old one close enough, or likely to be past its best ?

[dzl]

OK...so your original coil is good. Your generic spare is ok but not made specifically for the XT. I wouldnt use it on the XT due to the lower primary resistance.

You have 12V at the coil you said so you should check you have the 12V feed from the other side of the coil to the TCI. So check have 12V at the TCI orange wire.

Check you also have 12V at the red/white wire at the TCI when ignition and run switch on.

You can check the pulse coil feed is getting to the TCI also. Put meter leads on the green/ white and blue/ white wires. Put meter onto AC volts. You should see between .5 and 1 V pulsing voltage when cranking the engine.

If all of the above checks ok then start looking for a replacement TCI

You are sure there is no spark? Spark plug body being held against engine when cranking?

There are some other threads here about aftermarket TCI's available if you do need one that have proven to be good quality and reasonable price.

[motorang]

Hatrack, I sent you a PM a while ago. May be worth reading. Top right under the search field if you are in full view not in mobile.

Andy

[Hatrack]

Hi Andy
I couldn't find any such page nubers in the manual, so at the time, I gave up looking.
Today I found the pages you probably meant.
If I had the manual beside me in the workshop, rather than just indoors on the computer I can see that it might help,but as it is, all I can say is, I have tried a lot of the tests they suggest, though not exhaustively.

[Hatrack]

DZL,
Refitted the original coil and reconnected wires to it. Still no spark.
Orange and Red/White wires tested at coil and at TDI unit, live at both ends, with ignition on.
Testing the Green/White and Blue/White:
I found a likely looking Green/White but unsure how to test. That wire to the Blue/White or that wire to earth, I tried but no result. But possibly I had the multimeter on the wrong setting.
The Blue/White goes to the starter relay, which seems unlikely to be involved.