Forum

[Cranky]

I have read that the 500 UCE with a EFi has an ignition advance of 36 degrees( thats a lot). This information was by a participant of a forum. Has any one any further information on this. Has anyone ever strobe'd the max advance.

I mean how do you know it has any advance at all, many motorcycles don't. I know that the mechanical advance does --you can see that it does, but Im not sure about the ECU types.

[PeteF]

Many motorcycles don't have an advance????

[Cranky]

Many motorcycles don't have an advance????

No - the cdi unit is refered to as a flat liner. Probaby American terminology. Most small bikes dont.

[Rattlebattle]

I don’t know the definitive answer but my guess is that it doesn’t. Like a lot of smaller engines the ignition on the EFI relies on a wasted spark triggered by the generator each engine revolution. In my time I’ve had a few Brit singles with manual advance/retard. Unless fitted with a sidecar the retard was only used to kickstart the engine, after which it was run on full advance. I believe that, in addition to protecting the sprag clutch from damage should the engine kick back ( as used to happen on the Electra and early UCE models) the decompressor mechanism may also assist in starting the engine on full advance. This is only speculation, though it would explain why no ill effects are noted when the Hitchcocks carb conversion is done. This isn’t a high performance, high revving engine, so it might not need auto advance. Pure speculation as I said; the alternative is that the advance curve is programmed into the ECU just like, say, a Boyer unit, which also relies on a fixed trigger point. Does anyone know the definitive answer?

[Adrian]

If my memory is correct the ignition advance on the classic Indian Bullet is 32° before top dead centre (BTDC) on the firing stroke fully advanced, 8° BTDC fully retarded or no movement in the advance and retard mechanism.

When you say NO advance, are we mixing this up with FIXED advance as on two strokes and some racers?

You certainly can get TCI and CDI with an advance curve as opposed to a fixed or very limited variation in advance (the "flatliner" you came across) with the electronics varying the ignition timing in the place of the old mechanical advance and retard units. The previous RE importer in the USA marketed an electronic ignition for the old Bullet that had a switchable TCI unit with two different advance curves, one a bit sportier than the other.

This video with the spelling error in the title shows the difference (CDI rather than TCI in this case).

https://youtu.be/smFVTlX3FVc

When the Electra-X came out there were concerns about the accuracy of the crank-mounted ignition system, inconsistent machining of the crankshaft key-way meant that on some bikes the ignition was slightly too far advanced at all revs. Our hosts brought out a series of stepped alternator rotor keys which allow owners to vary the position of the rotor on the crankshaft to compensate.

https://accessories.hitchcocksmotorcycl ... tepped+key

A.

[PeteF]

Well, I'm willing to be corrected but I would have thought no petrol engine would run without some sort of advance.
Even the lowly Briggs & Stratton lawnmower engines have an advance built into their "Magnatron" flywheel ignition system.
Blimey, even the 25cc engine on my strimmer advances the ignition as the revs go up!

[Cranky]

What im trying to get to the bottom of is this. The tab passes the hall effect trigger and when it leaves the trigger it sends a message to releases the charge in the coil (dwell) and we get a spark. Some where along the way the CDi says --Ah we are going faster now so we will use the begining of the tab as a 36 degree max advance.

The flywheel Dia on the ECU is 118mm so X 3.142 / 360 it near as damit comes out to a degree per mm. Hence the tab is 36mm. Easy --

And so on increment of RPM it delays the leading edge signal to some where between max advance and then retards that to the other end of the tab to 10 degrees before TDC for initial timing.

Clever little box if it does all this and I can buy a 5 pin Dc CDI for just a nudge over a pound.

So has any one seen it do this. I know the flatliner I am using does not. But according to the wonderfull internet not many bikes do. I think they mean small scooters and buggies N stuff.

I have never strobed a motorcycle because its all in there and there is nowt you can do about it anyway.

[PeteF]

All very interesting but can you explain your statement that many motorcycles don't have an advance, as I've never come across one on 55 years of messing about with engines.
Please quote me one.

[Adrian]

Refresh my memory, what sort of ignition have you been using, TCI or CDI?

A.

[Rattlebattle]

My very first bike was a Honda C114, a little 50cc motorcycle that had 4 gears and a manual clutch but was otherwise essentially the same engine as the original OHV Honda stepthrough. It had no oil pump and the ignition was provided by a flywheel generator, like those used on umpteen Villiers engined two-strokes. That had fixed ignition ( as someone pointed out, what I think is actually meant by the expression “no advance”) Essentially it had no facility to retard the ignition for starting, nor did it need this. Small 4-strokes can easily run with fixed ignition.