Hitchcocks Forum

I've got a very puzzling fault, for the want of a better word, since fitting our host's enhanced TCI unit to my Electra X. Very occasionally as soon as I turn the ignition on there is a noise like the engine is trying to turn over. It lasts too briefly to pin point what is actually happening. At first I thought it could be the common stuck solenoid problem operating the starter but thinking about it further if the relay was stuck then the starter would operate all the time, irrespective of ignition switch position. I then thought it may be the TCI unit discharging, or something, causing the coil to fire the engine briefly. Perhaps the intermittent nature is due to whether the engine has stopped in a position where a stray spark would have an effect. All seems unlikely but something is going on. Has anyone else fitted one of these unit and noticed the same?

Hi guys---------- FRANK, why not phone our hosts and ask them directly ??-------- The ignition key is merely a "Make & Break" item, just like a set of points are....My Classic 500 will sometimes fire the odd one when switching the ignition off after the engine has come to a halt via the decompressor.....The engine can come to rest in one of two places, one of which will see the points closed....By then turning the ignition OFF it's as if the points had just opened and a spark is generated........................Maybe the new TCi unit is more sensitive to "Engine Stop" positioning ?? ------------ Give the lads a call and have a chat !!

Hi Alan, Thanks, yes I think you are on the right track there. As far as I can make out it only does it when restarting after a run and only the once, i.e turn the ignition off and on again and it won't repeat. I think I'm going to have to prove that it is firing by pulling the plug cap off before turning the ignition on. Because of it's intermittent nature it may take a week or so to conclusively prove!

One thing that is possible is that they run a wasted spark system so it is quite possible it is throwing a spark depending on crank position

Hi Frank, I think your on the right track with the cause.. One test for these TCI ignitions is if you turn on the ignition and then hit the kill switch (off) the primary field collapses in the coil and it produces a one off spark. This is regardless of crank position... It would be interesting to know if it throws out a single spark when you turn on the key...

Wondering if the hot engine comes to a halt, partially on compression and, you turn on the key after buying the newspaper and pop.. one spark and engine turns..

Backwards i would have thought... Reckon your rings and valves must be in excellent condition to hold that compression for minutes...

Why not try stopping the motor on the decompressor if fitted.. See if it makes a difference, no charge no bang... Interesting...

Hi
I had something similar on my Electra X when I first fitted the updated TCI. Mine was more troublesome though, as I also had leg-breaking kickback when trying to start the motor on the kicker. Long story short (sic), the coil was on the way out and firing at will rather than waiting for a signal. New coil solved both the extra spark and the kickback in one. HTH. Stephen

Thanks to all. I'm going to have to do a bit of experimenting to see if I can isolate exactly whats going on and in what circumstances. It ran perfectly ok before the change and indeed runs fine after, just with this odd intermittent occurence. Perhaps a classic case of if it ain't broke don't fix it!

After connecting a spare plug up and laying it on the head I can confirm that it does produce a spark every time the ignition is switched on, a strong one at that, regardless of engine position. Therefore it looks like given the right conditions, temperature and engine position it's enough to fire the engine and turn it over. I don't think any harm will come to it, unless as Gwilly says it's turning over backwards, in which case the sprag may suffer, but I will have to experiment with kicking it over tdc before turning it on or use the ineffectual decompressor.