Tri Spark woes

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Isn't full advance on the TriSpark 28/29 degrees? I thought 31 was for Boyers
Full advance is whatever you set it to. Workshop manual 06.5146, Rider's manual 06.3852, and Rider's manual 06.6240 all say 28 degrees. IMHO, you can easily go to 32 with high test gas containing ethanol.
 
Yes, agreed. But TS recommend 29 degrees.

Tri Spark woes


https://www.trispark.com.au/assets/files/Classic Twin Manual Final V8.pdf
 
Full advance is whatever you set it to. Workshop manual 06.5146, Rider's manual 06.3852, and Rider's manual 06.6240 all say 28 degrees. IMHO, you can easily go to 32 with high test gas containing ethanol.
But doesn't that also make the low rpm more advanced and more likely to kick back?
 
I once had a Honda CR-V car which blew random bulbs at an alarming rate ( I seem to remember about 15 in a year). I checked everything I could think of i.e. battery overcharging, loose connections etc. but could not find a reason. Then I saw these for sale, fitted one and never had another failure.

https://www.conrad.com/p/kemo-car-voltage-spike-protector-857474

https://asset.conrad.com/media10/ad...n-857474-kemo-car-voltage-spike-protector.pdf

It simply fits across the battery. For the money it's probably worth fitting to anything which has electronic ignition.
 
I'm with cliffa...
If you set it at 28 BTDC where is it at at kickover speed?
 
But doesn't that also make the low rpm more advanced and more likely to kick back?
Yes, but I've never had a kickback with Tri-Spark at 28 through 32. With points, you have a 24 degree advance. So, you're at 4 degrees while kicking (assuming the AAU is working correctly). Kickback doesn't happen simply because of timing - it has to do with crank rotation speed, momentum, and advance.

I'm fully aware that Tri-Spark lists 29 degrees. Why does anyone accept that when Norton said 28 degrees?

The best advance depends on many factors. Engine design, fuel, altitude, temperature, etc.

I generally run Combats at 31 and other Commandos at 29 but this one I have at 32 to see if it pings. So far, it does not.

BTW, Triumph uses 38 degrees for most, if not all it's models.
 
i think you have it backwards. 31 in a combat wound need a lot higher octain fuel than whats at the pump. usually with an increase in compression calls for less timing and a triumph has a lot slower burn with the deeper chamber and the big lump on the piston in the chamber.

I generally run Combats at 31 and other Commandos at 29 but this one I have at 32 to see if it pings. So far, it does not.

BTW, Triumph uses 38 degrees for most, if not all it's models.
 
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i think you have it backwards. 31 in a combat wound need a lot higher octain fuel than whats at the pup. usually with an increase in compression calls for less timing and a triumph has a lot slower burn with the deeper chamber and the big lump on the piston in the chamber.
I realize what I'm about to write is not for a combat engine but it will give you an idea of what Norton thought about this.

Service Bulletin N3/56 tells you how to turn an 850 into a Combat-like engine. As a part of that, it says that the timing should be Points: 30 degrees at 3000 RPM; Electronic Ignition: 31 Degrees at 5000 RPM.

If raising the compression and installing a hotter cam (among other things) dictates more advance then it's not unreasonable for Combat. Yes, I'm aware that the Combat was specified at 28 degrees in most documents.

All that was decided about 50 years ago. Fuel is different now and octane ratings are different now (at least in the US). Within reason, more advance will give you more power unless it pings - pinging cuts power and can do damage.
 
the rules still apply higher compression calls for less timing unless you put an obstruction in the flame path. there is a difference in fuel today. you cannot buy what would be 100+ octain at the pump like sunoco 260 and you could get away with 10-1 compression on the street back than. when i build a combat now i machine the piston tops to drop the compression with todays fuel. no way no how would would i puse the timing up on a combat.
PS it will ping long before you hear it.

If raising the compression and installing a hotter cam (among other things) dictates more advance then it's not unreasonable for Combat. Yes, I'm aware that the Combat was specified at 28 degrees in most documents.

All that was decided about 50 years ago. Fuel is different now and octane ratings are different now (at least in the US). Within reason, more advance will give you more power unless it pings - pinging cuts power and can do damage.
 
The benefits of having studied calculus...
The chart below is to show an example of the complexity of the topic of ignition in engines. Folks ask what is the "ideal advance curve"? Most folks unfortunately don't even come close to understand and are stuck in kindergarten.
To fully understand how little you actually understand, if you think there is an answer without a full disclosure of all the information about the engine you are trying to apply a particular curve to.

Think of the grid pattern as moveable left and right within the colored nonlinear spacial plane. The intersection in one axis would be the cylinder pressure based on the throttle setting. The pressure would obviously change dramatically. The ignition curve is a fixed single plane concept around RPM only and completely disregards throttle open, therefore disregards the pressure, cam selection, compression ratio, fuel, air temperature, engine temperature .
Ignition curves offered are by necessity default designed for WOT. That makes them very retarded for light throttle cruise. You are therefore slave to the curve you are given and the only setting you have is, where to set the curve in relation to the crankshaft... called initial timing. This chart is only to show "a complex nature condition" nothing to directly be norton or ignition related.
Tri Spark woes

Anything is possible with enough effort, money and applied technology. The nortons are almost stone age in the sophistication of the ignition curves offered. As a technical comparison my Ram/CumminsTD 3500 which weighs 7700lbs has on occasion, gotten 27MPG. The computer controlled injection with the wide variety of additional supporting equipment to insure tremendously low NOX and HC emissions.

NHT do not have any sensors, except one, the rider who feels the kick back or hears the pinging . The advance curves are all below the WOT "ping point curve". Some ignitions may come close. Some are not to close and you loose performance. The dyno shows this performance loss across the band. Where individual engines can be tested and data accumulated improvements can be made.

Nov 1989 in the beginning my final conclusion
"My first Commando, bought new in July, 1970, was an unmitigated disaster. In September, 1987 I bought my second Norton Commando, a '72 Combat, and to insure some useful life for this motorcycle, I have been studying everything I can get my hands on. I've learned quite a lot in nineteen years, part of which is patience and skepticism, and part of which is the subject matter for this writing, that being ignition characteristics, primarily those of the Boyer.
snip
simple agreement with the concept that one advance curve fits all is too much 'Black Magic' from the 'Black Box' for me to accept."

After 30 + years I now understand fairly well all the severe limitations of the ignitions applied to the wide variety of levels of tune of the NHT.

Feel free to go to my website and review in full @ the "information library"..."norton"...
http://atlanticgreen.com/boyerexposed.htm

http://atlanticgreen.com/boyerevolved.htm

We have obviously strayed from TS failure mode, to ignition suitability, and have gone to an immensely more complicated topic. frying pan into the fire.
If some intelligent person wants to start a new thread, I may comment other wise I'm leaving the sandbox.:rolleyes:
 
This is all WAY above my head !

What I do know is that on the dyno I moved the timing several degrees either side of the book figure with no discernible impact. So I run it stock.
 
I'm leaving the sandbox.:rolleyes:

I too am out. I tried ask a question about an already off-topic subject and to provide a little reasoning for that question about 18 posts ago. It has since devolved into nonsense IMHO.
 
The recommended 28°advance is at sea level.
At higher altitude you can (should) increase it a few deg.

Yep, my TS is set at 33 degrees (6400 feet). No kickback at all with TS at that setting when I still was kickstarting (now Alton E-start).
 
At the other extreme and beautiful it its simplicity is fixed timing:

Once a Norton is started you don't really need any advance at all. Fixed timing works just fine because you're not really loading the motor under 2000 RPM anyway. Good pull form low end to red line as demonstrated with fixed timing magnetos (although now there is a new custom order magneto retard lever just for starting).

Tri Spark woes
 
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