Wasted spark?

[Kiwi_Roy]

I just installed a digital tach on my 15M system.  I connected it to the tach output.  Set to 2cyl it gave me what I figure was 2x rpm.  Set to 4cyl it's accurate.

Doesn't answer the question, but it implies that the ecu is firing twice.  It's not feeding both coils at once though.  If it did that we wouldn't care about left/right plug wires.   

Maybe someone over at the guzzidiag topic knows.

It sounds as though just re-routing to one coil should do it then, stands to reason a tach manufacturer is more likely to make it for a system it's likely to strike rather than some obscure. weird Guzzi.

[Wayne Orwig]

I doubt that the COIL has a waste spark. The coil being fed by the ECU, and the ECU timing being fed by the cam. They would have to work to put in the second spark. You normally only get into waste spark situation when timing is generated at crank speed, or the cam has two trigger points.

 

[Rough Edge racing]

90 degree Ducati V-twin, at least the old carburettor versions (900SS, Monster etc.) with the 2 pickups on the flywheel have wasted spark ignition.

  I have a carburetor 900 m and it sure does look like each coil and pick up is independent from the other...So Each cylinder fires every 360 degrees rather than 720, but not both cylinders at the same time like a Harley or some Japanese machines...

[Bill Owens]

How do you explain Rodekyll's experience?

[Rough Edge racing]

Do you mean every PLUG fires at the same time, not every cylinder. Thinking... thinking...

The front and rear cylinder each fire independently every 360 degrees. So one waste spark per cylinder but never both cylinders at the same time....The two ignition sensor/pick up is on the crankshaft spaced 90 degrees apart...

[oldbike54]

 Huzo old buddy , think 180 or 360 degree engines .

 Dusty

[Dukedesmo]

Quote from: Rough Edge racing on Today at 09:27:49 PM

The front and rear cylinder each fire independently every 360 degrees. So one waste spark per cylinder but never both cylinders at the same time....The two ignition sensor/pick up is on the crankshaft spaced 90 degrees apart...

Indeed, the cylinders obviously fire on the compression stroke but also fire 360 degrees later on the exhaust stroke but each cylinder fires independently of the other, i.e 90 degrees apart as the pickups are set one 90 degrees after the other, but as they are on the crankshaft the flywheel triggers the spark every revolution whereas the cylinder only needs to fire every other.

If you take the pickup from the camshaft drive at half engine speed (as per a Guzzi distributor) then there would be no wasted spark - there is a company in New Zealand that make a conversion to do exactly this; http://www.fastbikegear.co.nz/

[Kiwi_Roy]

[
 - there is a company in New Zealand that make a conversion to do exactly this; http://www.fastbikegear.co.nz/

Dammed Kiwi's never can be trusted

[Dukedesmo]

Quote from: rodekyll on Today at 07:53:05 PM

I just installed a digital tach on my 15M system.  I connected it to the tach output.  Set to 2cyl it gave me what I figure was 2x rpm.  Set to 4cyl it's accurate.

Doesn't answer the question, but it implies that the ecu is firing twice.  It's not feeding both coils at once though.  If it did that we wouldn't care about left/right plug wires.   

Maybe someone over at the guzzidiag topic knows.

___________________ ___________________ ___________________ ___

Unless you're connected to an output that signals both cylinders then it does imply that it's firing twice, i.e wasted spark.

I have Translogic digital dashes on both my Ducatis; 916 (16M ignition) and 900 Monster.

Both are 90 degree V-twins and the RPM pickup comes from the signal to just one of the coils, to configure it properly you then set it to a (sequential) setting that gives the correct number of pulses to show the correct RPM.

The ignition pickup points are different in that the Monster has 2 pickups on the flywheel which (obviously) runs at engine speed whilst the 916 has a single reference point on the cambelt pulley layshaft which runs at half engine speed, it then use the ECU to generate the spark based on degrees of rotation.

The 916 is set at the second setting, i.e. twin cylinder (no wasted spark) but the Monster needs to be on a higher rate (as if it were a 4-cylinder) due to the wasted spark, otherwise it reads double-RPM.

[drums4money]

I doubt it, usually on singles or twins I think where the cylinders go up and down in unison


Update
LowRyter know a lot more about this
The only bikes I'm familiar seen the NSU Supermax and Kawasakis
I don't think the Brit bikes use it.
I doubt any bikes with 180 or 270 degree cranks use it

My BSA Thunderbolt A65T & Honda CL200 both fired plugs in unison. 

[Rough Edge racing]

My BSA Thunderbolt A65T & Honda CL200 both fired plugs in unison.

  An A65 using the stock points ignitions has two separate systems and fires one plug at a time...

[drums4money]

  An A65 using the stock points ignitions has two separate systems and fires one plug at a time...

Ah, yes.
It wasn't stock.  Points setup had been replaced with electronic ignition. 

[ITSec]

Dammed Kiwi's never can be trusted

What do you expect - they think cows are good for show-jumping! http://www.cbc.ca/radio/asithappens/as-it-happens-wednesday-edition-1.3920983/she-didn-t-have-a-horse-so-this-new-zealand-teen-rides-her-cow-instead-1.3920989

[oldbike54]

 Well that was the best thing I've ever seen . A jumping cow , simply amazing 

 Dusty

[ITSec]

Well that was the best thing I've ever seen . A jumping cow , simply amazing 

 Dusty

A high-jumpin' heifer.... who'da thunk it? I figgered them Oklahoma boys had already done all that could be done to make a cow jump. 

[oldbike54]

A high-jumpin' heifer.... who'da thunk it? I figgered them Oklahoma boys had already done all that could be done to make a cow jump. 

 Seems you are confusing Oklahoma with Nevada 

 Dusty

[ITSec]

Seems you are confusing Oklahoma with Nevada 

 Dusty

Oklahoma - where men are men, cattle are nervous, and sheep are resigned to their fate!

[pikipiki]

Just my tuppence worth, was that tacho of an old bike with non ecu twin coil system? If so the tacho probably took a signal from low tension on just one coil?

Regarding wasted spark only system I seen is the Citroën flat twin that's definitely wasted spark for similar reason to above for 4 stroke singles.

Surprised to see so many large capacity relatively modern engines mentioned as wasted spark. Might explain a few LPG conversion disasters?

[Kev m]

Wasted spark on V twin bikes? Millions of 45 degree Harleys in the past...Don't know if they still use it...

The Sportsters stopped using it by the rubbermounts (2004) and maybe earlier on some models (1200S?), not sure.

I'd assume the BT's abandoned it earlier.

[Pancake]

I fitted a Newtronic (formerly Piranha) ignition on my Guzzi and occasionally get blowbacks which blows a carb off. One blowback was so severe it broke a rocker arm. I'm not sure if it has a wasted spark system but I'm starting to suspect this is what is causing it. Sometimes just pootling around a carb will blow off. If, when checking something like lighting for example, I turn the ignition off and on a couple of times, a carb will blow off.

It's bloody annoying, but compared to the points, it starts much easier than it used to.

[acguzzi]

I have a piranha on mine, it doesn't have a wasted spark

[Pancake]

I have a piranha on mine, it doesn't have a wasted spark

Thanks, that's reassuring. Except that means there must be another reason for the carbs blowing off every now and then!

[Don G]

Switching the system on/off causes a spark, Boyer ignition and Lucas Rita did the same on the Brit bikes..... DonG

[Tobit]

Wasted spark?

My morning erection.

 

[Pancake]

Switching the system on/off causes a spark, Boyer ignition and Lucas Rita did the same on the Brit bikes..... DonG

Ah...OK thanks, that explains a lot!