PROGRAMMABLE IGNITION
Steve Cooper on why it’s best to bring this modern innovation on board.
If you look at any older, four-stroke, motorcycle (post Edwardian period) chances are it’ll have a little stubby lever somewhere on the bars connected to a Bowden cable.
Follow the cable and you should end up at some form of HT dissemination system, either a distributor or magneto. The lever and cable move one component relative to another thereby facilitating a level of variable timing. Initially installed on bikes to assist easier starting, the system also allowed optimal firing points, dependant on engine speed and load. In the name of progress and in a bid to make bikes a little more idiot proof advance/retard controls rapidly moved to an automatic system utilising springs, bob weights and/or vacuum triggered diaphragms. Delve into virtually any Japanese four-stroke and you’ll likely find something that uses springs and arms to alter the ignition timing. Unfortunately you won’t find the same on pretty much any Japanese two-stroke. About the only exception is some of the smaller twins with electric starters and the A/R units there are only used to give the electric foot an easier life. Simply put, until recently no one gave a rat’s arse about giving stinkwheels the same technical advancements that the poppet-valved motors had enjoyed for decades. No, those that love the simplicity of the stroker were cursed with a fixed ignition timing and one that was, at best, a compromise. The point at which the spark plug detonated the fuel/air mix was essentially a compromise between ease of starting, mid-range performance, decent torque, rideability and engine longevity. Sure you can alter the static timing to maximise one characteristic but it’s impossible to cover any of the bases successfully. You can tune a stroker as much as you like but unless that instant of explosive energy is delivered at precisely the correct moment chances are you’ll be wasting a slice of latent power and performance. Simply put, it ain’t cutting the mustard pal! And worse still it’s not unknown for stroker power curves to just flatten out at higher revs simply as there’s no spark advance available. Yes electronic ignition has been available on Japanese strokers since circa 1977 but few if any ran a genuine advance/retard curve and even the vast majority of retrofit, aftermarket systems have extremely limited A/R facility. The situation changed as the end of GP two-stroke racing dawned. The tech used to extract maximum reliable power from each class saw insane levels of horsepower being returned. How good would it be to have a slice of that? Okay so we’re not going racing but why not utilise the best technology around for our older strokers?
Like much of modern technology the installation of the Zeeltronic isn’t exactly riveting stuff but the end result has to be experienced to be believed. Starting is unchanged, the bike fires up instantly, but as soon as the bike is under way there’s a noticeable difference. Throttle response is livelier and the engine feels crisper. Once up to operating temperature the motor is sharper and responds to changes in throttle position almost instantaneously. Better still the elderly RD is noticeably faster; that front end can become decidedly light if you don’t watch it. And the benefits just keep on coming. One of my local test routes has a long dual carriageway hill with some decent bends that then unwind into a plateau followed by a short straight. Suffice it to say the 350 has been worked hard here and my terminal velocity, just as I hit the straight is now some 10mph higher than it was before fitting the Zeeltronic. And if that wasn’t testament enough as to the advantages on offer get this – it’s possible to roll the bike on 30mph in top gear with no spluttering, hesitation or lurching – and no, they never, ever did do that when they were new! Oh and fuel consumption has improved and exhaust smoke has diminished dramatically. Go on, fit a programmable ignition… you know it makes sense! cmm ■ Our thanks to Zeeltronic for advice and support: www.zeeltronic.com