Hitchcocks Forum

Has anyone got any comments or experience of this spark delay unit for the Electra X from our hosts?

http://www.hitchcocksmotorcycles.com/ne ... _Electra_X

papasmurf,



I believe they were originally developed by Watsonian-Squire as a stop-gap measure to try and help the earlier Electra-X bikes with the original style of black TCI box from lunching their starter sprag clutches. Their later green TCI box has the spark delay built in, so if your Electra-X-ish already has the green one you won't need the separate unit.



Some TCI ignitions don't like any sort of voltage drop, and they can go full advance if that happens. There's a note on Paul Goff's web site explaining that the Pazon was a better bet for electric start Mk3 Norton Commandos than the Boyer Mk3 (analog) ignition. The momentary voltage drop as a result of the starter motor kicking in would send the Boyer TCI into full advance, cause a backfire and easily kill the Norton sprag clutch, in very much the same way as can happen with the Electra-X. Pazon brought out their ignitions to be able to cope with reduced voltage, and Boyer themselves brought out their lower voltage-friendly Mk4 as a response.



From this I'm guessing that the same effect was killing Electra-X sprag clutches, although our hosts blame electrical noise. Using a spark delay, either as an add-on or built into the TCI box would allow the full voltage to come back up before the bike attempts to fire and reduce the risk (as does a really healthy battery), though I prefer the idea of a TCI that will simply work properly at reduced voltage.



A.

This may help - taken off a recent posting on 'News' on this web site: "The sprag clutch assembly on the Royal Enfield Electra X has been known to fail under certain conditions. As repair of the sprag clutch is an expensive option it is advisable to take any measure that may prevent or reduce likelihood of failure.

One cause of sprag clutch failure is engine kickback. A kickback forces the engine in a reverse direction. As the sprag bearing is designed to rotate in only one direction an engine kickback puts excessive stress on the bearing often resulting in its total collapse.

On certain Electra X engines electrical noise interferes with the engine’s electronic control unit. This leads to the ignition unit producing an additional, rouge spark - giving excessively advanced ignition timing. If the engine has not achieved sufficient forward momentum the advanced ignition causes an engine ‘kickback’ with sufficient force to destroy the sprag clutch.

To minimise the risk a spark delay unit can be fitted which allows the engine to achieve sufficient forward momentum before ignition occurs. The spark delay unit is easily fitted and inexpensive. Part number 581028 at £11.00 plus postage and VAT."

I like the idea of a rouge spark. It's like the opposite of a bleu one...

So no-one has fitted one of these devices then. (The electrics are packed somewhat tighter than normal on my Electra X (ish) due to my having to reroute all the wiring under the top frame members where seat sits so I could fit a very low seat.)

It would help a bit, but I could never get mine to work and junked it when the tappet cover plate cracked around the valve lifter spindle and started leaking oil out. I did later work out how to fit a proper Bullet decompressor to an Electra-X head, but that's another story.



Papasmurf, you did ask for comments as well as experiences... Like I said, if you have the later green TCI amongst the electrical gubbins you don't need a separate spark delay unit. If you have the older black TCI still fitted and you use the electric start, I'd get one!



A.

I will have to check the TCI.

Hi guys------the REAL problem lies in the use of a SPRAG rather than a ROLLER freewheel clutch........