I was given a non running '93 3YF which I finally got running recently, although it would only run on full choke ! After welding up a big hole in the exhaust, the bike would not start at all. Checking the plug, I noticed a very week spark so I replaced it with a new one. Now it won't spark at all even though the old plug still gives a weak spark. Coil and plug cap seems ok so why no spark ?

Did you weld the pipe while it was on the bike?

Mezo.

Mezo wrote:Did you weld the pipe while it was on the bike?

Mezo.

...............with the battery connected?

Possibly fried the TCI (Thyristor Controlled Ignition) similar thing to a CDI (Capacitor Discharge Ignition) on earlier Xt`s.

If it was working up until you did some welding that could be the cause?

This guy has two for sale.

Mezo.

If you welded with everything connected the alternator will need checking as well.

Rick

My welder has told me he is not a plonker and removed the exhaust system before welding

Make sure you are getting 12 volts to the coil, the red/white wire.

How did you check the coil?
Is the HT lead ok? They get hard & brittle over time.

Rick

Jools wrote:My welder has told me he is not a plonker and removed the exhaust system before welding

Easy enough to prove by looking at the nuts where it bolts to the head, caked in mud or rust means welded in situ.

Mezo.

Having problems finding a replacement coil, would any 12volt motorcycle coil do ?

I think I have a spare amongst all the bits in the workshop, I will check tomorrow.
If not, Halgeir has one from the bike he's breaking. And probably all the rest of the electrics if urs are cooked?
I'm on the surrey/sussex boarder if I can help?

Adrian