No spark 1990 3TB

[Hatrack]

Thanks, I checked their site but no TCI listed.

[dzl]

Hi Hatrack....pickup coil definately working ok. I think youve now checked all inputs into the TCI as being ok. Where abouts are you located? Anyone around that could lend you a TCI?

[Hatrack]

Thanks. I'm in South West UK. I don't know anybody with another XT or anybody who can lend me one. There are one or two bike shops that still understand older bikes. I can try asking there.

[Hatrack]

Just ordered a Carmo ignition box. I like the improvements they list and the two mounting holes, as I don't have the air box to mount it off. While saving up I have been busy sorting out quite a few small things out on the bike. So when the new TCI arrives, fingers crossed, there will be sparks and all systems go.

[Hatrack]

Well that's disheartening !
Carmo box of ignition wizardry arrived last week. I fitted it and was trying it to see if there was a spark at the plug but as I did so the starter motor slowed and stopped.
When the bike was running, nothing suggested the battery was past it, and I had put it on an Optimate trickle charger for much of the time I was working on the bike, so initially I was more worried that the starter might be failing or the sprag clutch siezing up.
So I got the starter out and tried running it on that battery, on the bench. It ran but only slowly.
I charged the battery, did the same test and the starter motor fairly wizzed round, so no worries there, it had to be the battery so yesterday at 4.15pm I ordered a new lead acid type from Tanya, and it arrived at 9.30am today ! (that is not the disheartening bit).
So obviously I got the stater motor back in place and once I was sure the new battery was fully charged, on it went.
I looked to see if there's a spark at the plug, and still nothing. You guessed it, that is the disheartening bit !
So, I did all those tests you helpful guys suggested, and could only assume it needed a new CDI box. I'm not complaining about your help, but obviously there is something else that aint right.
Its crossed my mind that maybe the Carmo CDI is faulty, but that is hardly likely.
When I'm a bit more in the right frame of mind, I'll do those tests again and see if anything different shows up.
I am getting desperate as I want the bike for a trip in 2 weeks time and at present its looking unlikely.

[dzl]

Damn. OK. perform some checks again......

When cranking the engine are you still getting voltage pulse from trigger coil when cranking engine on green/ white & blue / yellow wires at TCI plug. You did check before and had 2V AC when checking on AC setting on meter?

Do you have 12V + on red/ white wire on ignition coil when ignition switch turned to on?

If yes to above, when cranking do you see the voltage pulse on that red/ white coil wire? Should see about 6V pulsing on it when cranking. Set volt meter to manual range 10 or 20V DC setting? Other meter lead to negative/ chassis.

[Hatrack]

Thanks for that summary of the various checks.
Yesterday I trawled through the thread to get some sort of list of them so that I could run the checks again with the Carmo TCI. Busy today, but look forward to a thorough check of it all tomorrow.

[Hatrack]

OK.
It seems to check out with the results you suggest.
I had a bit of trouble setting the correct range with the new "better" meter, mainly because the "English" translation in the instruction book is rather strange, but give or take a decimal place, the numbers came up pretty much as you suggest they should.

[dzl]

Well you have a voltage switching on and off at the coil so the TCI is doing its thing. It has to be making a spark if the coil is good! Think you checked the resistance of coil earlier as ok. Possible may be breaking down internally under high voltage. Perhaps try your other "new" coil ?

[scottieh]

This may be a long shot but it's worth asking as I haven't seen it yet: have you tried disconnecting the on/off switch wire at the TCI? That wire can ground out the TCI box (at least it does on the older model CDI) and cause no spark similar to the neutral and clutch kill switch. It may be a black/white wire with a bullet connector at the TCI, but I am saying this based off my memory of older model CDI's. I don't have a wiring diagram for reference.