This is from desmo.org.uk but I would like it kept in more than one place!
(Currently fitted to our 600 Pantah engines Spondon)
This pic shows the adapted Pantah cover on the 900 engine and the extended nut poking through the hole.
Why fit a Lucas Rita ignition to a Pantah (belt) engine? Well in my case I had 900 Paso engine to fit into a Spondon frame and needed an ignition system for it. A new Digi box would cost a fortune,add to that the wiring loom and you are talking serious bucks. The Rita on the other hand would cost you some ware in the region of £120 for all the ignition bits, which if any break are available individually nice and cheap. If you have an old Pantah then you no doubt know about the pick-up’s falling apart as the wiring was not really designed to be bathed in hot oil- which the Rita doesn’t.
The ignition in cross section shown mounted on the cam belt cover.
Other bits you need are a spare front Pantah belt cover (That’s the alloy ones fitted to the Pantahs and earlier 600/750 SS and Monster range) and you will need a special extended belt drive wheel fixing nut and a spacer made by an engineer (or a nutter with a lathe like me!)
The basic components of the lucas Rita. At the bottom is the Reluctor, above that is the extended drive wheel nut that the reluctor mounts on and behind that is the mounting plate which in turn mounts on a spacer(not shown) of the same size.
The idea of this ignition system is that it mounts on your belt cover and is driven by an extended nut on the end of the half speed shaft that drives your cam belt. Steve Wynn (Sports Motorcycles) used to use this system on his Pantah racers as it enables you to play around with the advance retard.
I’ve done this conversion twice now, once on a 900 engine and once on a 600 Pantah. In the case of the 900 a couple of us who had built 900Paso Spondons put them on the Dyno. We both had the same Mukini carb conversion; the only difference was he used the standard Digi box ignition. Both had the same power output.
On the first conversion I took a 500 Pantah belt cover and cut it so it matched up with the top 900 cover, and machined a flat were I intended on mounting the Rita before drilling a hole in line with the half speed shaft to let the extended nut through. But on the second conversion I didn’t bother with the flat and it looks and works just fine!
One advantage of the Lucas rita is that it gives a very fat spark, but this can also be a bug bear as the coils are working harder and in order to avoid then burning out the best coils are the oil filled ones. I use two 12v coils in parallel but I know others that use two 6v items in series OK, so it’s a question of what you can get hold of. The old Meridan Tridents used the correct coils and they usually go for a song, so whenever you see some at an auto jumble, its always worth buying a set as you get a spare thrown in!
Fitting the ignition is pretty straight forward once you have got all the bits made, as is setting it up, but its worth knowing a few tricks!
Always lock tite the reluctor to the extended nut as there are no locking devices. None of mine have ever slipped using the stuff, although I do keep an eye on the timing when I service it to be sure!Get your engineer to make a nice alloy cover up for it, my first cover was made from a spray can top and a stone smashed through it and damaged the pick-ups!
Setting up is a doddle. If you buy a Lucas rita new you should get instructions for this. Just set it up the same as an 860GTS and It’ll work just fine. If you don’t have instructions drop me a line and I’ll send you a copy. The thing to remember is you set it fully advanced on the rear pot and then move the pick up 5mm back. It is very easy to set up the pick up with the front on the back, but you can check this by turning the engine to the next TDC mark and making sure the other trigger on the reluctor is lined up the same- if it is not, your back to front!
Once you’ve done it a couple of times it takes about 3mins to set up and if you are racing and want to play about with the timing its really handy.
The only draw back is you cant set it up with a strobe light as the rita is a wasted spark system that confuses the strobe light no end!
Clear as mud? Well it works for me!