I've been looking into this & posting on the 'Ignition Timing' thread, but think what I've discovered merits a new thread...
Things are looking very good - whereas I thought I might have to do some mods to a unit & source & test it with a replacement custom ignition rotor (& perhaps offer a kit), I've discovered a unit which has pretty much everything we need & will work with our stock rotors.
The unit, Sparker TCIP-4 is made by a small Czech company called Ignitech
Cost is about 130 euro plus an adapter cable, maybe $190 or so for a straight plug in replacement kit. RPM/Advance curve adjustable, if you want, via their supplied software, PC & (standard RS232) Serial Port
But, for those who want to do some mapping, the unit can take an input from a throttle position sensor (TPS) as-is, or manifold (vacuum) air pressure sensor with a little bit of circuitry to give the required signal. Thus a 10 by 10 point 'map' RPM vs TPS (or intake vacuum) of ignition advance can be set with linear interpolation between points.
Neat eh ?
I read through a long thread on a Ducati Monster forum of people who have fitted this unit on their bikes. A technician called Brad Black has also played quite a bit (with it on a Duc) & posted up his conclusions on the web. The unit seemed universally praised, reliable & plugged&played happily even for folks not of a very tech/electrical bent. One minor issue arose with a small, but consistent - so workable with - error reducing advance below (so safe) that set as rpm increases. I have an idea why this is the case & plan to ask them if this is still the case & can they fix it in their software. In any event, I plan to confirm settings with a timing light when I've got set up.
I downloaded the software & they have a bike type listing for a Triumph Tigra (Czech for 'Tiger' I think
). I'm sure that all the T3s have the same ignition rotor & they have confirmed the unit's suitability for Tbird/Legend in an email to me. I need to send a photo of the ignitor connector block for him to confirm he can supply an adapter cable. (Looking at the those he has on the website I think he will be able to supply this.)
So...what remains is to figure out supply & fitment of a throttle position sensor OR inlet vacuum (MAP) sensor....
...if the latter, I gather what's needed is to take a pipe from each of the carb balance vacuum ports & collect at a plenum(box) very roughly 15cu inches in volume ~ say 2"x2"x4" in order to damp out oscillations & combine all 3 cylinders then connect to a sensor unit for conversion to electrical signal.
A TPS sensor might be a lot easier if some means can be found to connect it to the carb throttle shaft.
Any ideas here very welcome....
I understand that Bonnie's have a TPS/RPM mapped ignitor & have a TPS mounted on the side of one carb. Tho' ours don't have fitting point or access to the butterfly spindle on the outer carbs.
The attached pdf file shows Ignitech's 'default' map for the Tiger to show where this might be going. Stock RPM/advance for a Tiger runs from 5deg BTDC @ 1000rpm to 29degBTDC @ 6500 & above. It seems likely then that much higher advance could be applied to Tbirds at lower throttle/rpm points than stock igniter will give & improve power/efficiency/economy for beginning of acceleration & when cruising.