Electronic Ignition advance variations

I just spoke with Fred at Old Britts, thought I would go straight to the horses mouth.

#1 The actual timing on the stock Norton with points is not 28* because there is already a 5* pre set advance on the points plate.

#2 The power arc is in fact set at 36* The Power Arc sparks 3 times on each stroke, it is mapped to use Premium 91 octane gas with up to 10% ethanol The advance was set using stock motors on a dino and no changes are recommended for safe operation on the street with stock motors.

Comparing the power arc advance with any other system is a little like trying to compare apples and oranges,

My power arc should be here today and I should be ready to ride early next week. I wanted to be sure before I installed it and am completely satisfied with Fred's response.

I had done my research and it looked to me like the Power Arc was at the top of the currently available units.

Dennis

Congrates Jim on another advancement for ole Nortons with effective knock sensor. Pray tell what is the ping freq of Nortons? I thot the head ringing would sound the same as ping just less loud.

Dennis C said:

I just spoke with Fred at Old Britts, thought I would go straight to the horses mouth.

#1 The actual timing on the stock Norton with points is not 28* because there is already a 5* pre set advance on the points plate.


Dennis

Click to expand...

This is incorrect. Total timing is originally 28 degrees.

The advance available with the original advancer is 12 cam degrees or 24 crankshaft degrees.



That along with 4 to 5 degrees initial advance gets you 28 to 29 degrees total. Jim

comnoz said:

kerinorton said:

is that a knock sensor.

Click to expand...

Yes,
I have a 144 entry timing lookup table that uses map over rpm. It is loaded with an aggressive advance curve.

When the motor is started it uses the advance curve as it is loaded in the table. If the knock sensor hears a ping it will retard the timing at that load/rpm point 1 degree at a time until the ping goes away. Then it uses that "learned" timing figure from then till the engine is shut off. It does this for each of the 144 table entries.
When the motor is shut off it looses the memory and learns all over again the next time it is started. The sensor is sensitive enough to pick up very light ping so it will retard the timing before you even hear the ping when riding.

This is a new addition and so far it is working very well. I tried using it once before but had trouble with normal engine noises triggering retard but I found a tunable module to filter the engine noise so all it can hear is the ping frequency. Jim

Click to expand...

What make and model is your ignition system which adjusts itself from the knock sensor ? Can you reset it easily to the original advance curve when you adjust the jetting or change the comp. ratio , so that it adapts to the changes ? Or does that happen automatically ?

'When the motor is shut off it looses the memory and learns all over again the next time it is started. The sensor is sensitive enough to pick up very light ping so it will retard the timing before you even hear the ping when riding.'

Sounds too good to be true. Have you developed this yourself ? It really presents an excellent opportunity to get better performance by playing with the carb needle shapes. Needle jets usually come in increments of one thou inch. If you change the jet one size even with methanol the difference in acceleration of the bike is often quite dramatic. If you go larger then drop the needle to lean off, you still don't necessarily get the optimum rate of fuel delivery across the whole range from 1/4 to 3/4 throttle as you wind the throttle on coming out of corners.
My method of getting the needle and needle jet 'right' has always been to lean off until I get the motor to cough when riding it through corners, then raising the needle one notch so I no longer get the hiccup. That only probably gets the jetting at optimum at only one point in the throttle range. The shape of the needle does the rest, and if you simply accept what Amal provide, you get 'a one size fits' all answer - not necessarily the best.
If you look at the variety of Mikuni needle shapes used in different Japanese bikes, it makes Amal look very crude.

comnoz said:

Or you have your cake and eat it too.

Click to expand...

Jim, I take it that the item between the manifold and the head is the knock sensor. Are you selling them as an aftermarket item for use with a particular ignition system ?

The knock sensor is in the fins there at the back of the barrel.

It is only designed to work with the engine management system on my bike. Jim

How Hard would it be to fit a Knock sensor in the circuitry of the available ignition systems. Modern cars since the invention of computers all have knock sensors as far a I know.
Hobot, you cant always hear the knocking. When you do hear it, it is getting too late so that why we back of when it happens. Detonation is dangerous and often silent.
We used to run vehicles on CNG [ compressed natural gas ] in NZ. You had to advance the timing a hell of a lot to get that stuff to work. People with dual fuel cars would often run on petrol, when out of CNG and ignore the engine protesting. Then dual curve ignitions systems were fitted.
I once stripped a Mitsubishi engine that had stuffed its rings. There were detonation marks from the top of the bore to half way down. We did a test one day to see how far you could advance the timing. To our surprise, the pinking seemed to disappear when we went far to far with the advance. I can't explain why cause I'm only a mechanic and not a scientist.

My reason for dropping these comments on this discussion is based on my experiences with cars etc. We have modern ignition systems available but they are still old hat if they don't take advantage of modern technology [ knock sensors/computers etc. ] The mention above of the system that learns as it goes is good, but modern cars are designed to remember what they have learned, not relearn it over again. But to learn is far better than all the other systems out there. With this ability, you will then have a system that "designs itself" to fit your bike.

I like rock solid ideas and fixes on these bikes because the bikes deserve them. That's why when I think something is not up to the task, I will say so. Just because its worked for years, doesn't make it right. Those who don't like what I say are welcome to not like what I say. I like this forum because it puts forward many ideas and experiences. And quite honestly, there are no dumb questions. I wonder how many dumb questions A G Bell asked himself.

I'm a bit current on knock sensors, narrow band and wide band and spectrum analysis principles to filter to apply to Peel so Jim has pulled off a tough task to get knock sensor to actually be useful in ignition protection in ringy dingy norton rather than just be fooled by normal engine sounds over 6000 rpm and retard unneeded. Jim's is a one in a row though but maybe our ear with head phone or LED could pick up ping while tuning to avoid it. i'd mount Peels in top center of head steady bolt hole.

The Power Arc is a totally different Electronic ignition from your normal electronic ignitions, making
it very hard to compare advance curves (maps) and the amount of advance the ignition achieves.
I will try to show why we can achieve higher advances due to the three sparks per compression stroke.

Our pre-loaded stock mild map looks like the map labeled “Old Britts White Wire -12V”.

As you can see we can program all three sparks and the coil on a map. With over 350 ignitions
sold to Commando customers and only three units returned because they could not get the ignition
working to their satisfaction (the returned ignitions did perform well on our bench tester),
I think this map works well for normal Commandos.

I build a short stroke engine for a customer and it would not perform well with the stock map.
We were running a C2 ignition with 4 maps and I placed a switch on the console so we could easily
try different maps. We kept getting better performance with more advance. After trying a number
of maps we achieved almost our desired performance with the map labeled “Switch Position 4”.

However, we found the bike was bogging down around the ton and we came up with the map labeled
“Switch Position 3”. This map is similar to the map Kenny Cummings developed for his race bike:

Since the bike did not have a fairing, reaching around 100 mph was putting a load on the engine as
if it was going up a steep hill. Load on an engine required the ignition to be retarded and, as you
can see, we achieved this from the above map. With this new map we achieved performance well over the
ton. The first map, "Switch Position 4", worked fine through the gears but at high speeds "Switch
Position 3" worked best.

This was a specifically built, all new, short stroke engine where the normal Commando engine appears
to work just fine with our stock maps.

If anyone has more questions you can call me at (253) 735-2375 or E-mail me at fred@oldbritts.com.

Fred Eaton

kerinorton said:

How Hard would it be to fit a Knock sensor in the circuitry of the available ignition systems. Modern cars since the invention of computers all have knock sensors as far a I know.
Hobot, you cant always hear the knocking. When you do hear it, it is getting too late so that why we back of when it happens. Detonation is dangerous and often silent.
We used to run vehicles on CNG [ compressed natural gas ] in NZ. You had to advance the timing a hell of a lot to get that stuff to work. People with dual fuel cars would often run on petrol, when out of CNG and ignore the engine protesting. Then dual curve ignitions systems were fitted.
I once stripped a Mitsubishi engine that had stuffed its rings. There were detonation marks from the top of the bore to half way down. We did a test one day to see how far you could advance the timing. To our surprise, the pinking seemed to disappear when we went far to far with the advance. I can't explain why cause I'm only a mechanic and not a scientist.

My reason for dropping these comments on this discussion is based on my experiences with cars etc. We have modern ignition systems available but they are still old hat if they don't take advantage of modern technology [ knock sensors/computers etc. ] The mention above of the system that learns as it goes is good, but modern cars are designed to remember what they have learned, not relearn it over again. But to learn is far better than all the other systems out there. With this ability, you will then have a system that "designs itself" to fit your bike.

I like rock solid ideas and fixes on these bikes because the bikes deserve them. That's why when I think something is not up to the task, I will say so. Just because its worked for years, doesn't make it right. Those who don't like what I say are welcome to not like what I say. I like this forum because it puts forward many ideas and experiences. And quite honestly, there are no dumb questions. I wonder how many dumb questions A G Bell asked himself.

Click to expand...

I have the system set to relearn each time the engine is started. I can also set it to hold the memory like it does for the fuel but the idea is to relearn with each tank of fuel. I have found there is a lot of variation in the knock resistance of fuels -even if they have the same octane rating on the pump. Then of course there is the occasional premium pump that is delivering regular fuel like I found last fall.

Most all automotive systems have a base map that is used for startup and then it modifies it as you drive. I kind of followed their lead. The system on my bike has so far been completely transparent in operation. The only thing I notice so far is -no audible ping.

There are a hundred different ways to configure the system and I may find something that works even better as I get more time on it. Jim

Old Britts said:

The Power Arc is a totally different Electronic ignition from your normal electronic ignitions, making
it very hard to compare advance curves (maps) and the amount of advance the ignition achieves.
I will try to show why we can achieve higher advances due to the three sparks per compression stroke.

Our pre-loaded stock mild map looks like the map labeled “Old Britts White Wire -12V”.

As you can see we can program all three sparks and the coil on a map. With over 350 ignitions
sold to Commando customers and only three units returned because they could not get the ignition
working to their satisfaction (the returned ignitions did perform well on our bench tester),
I think this map works well for normal Commandos.

I build a short stroke engine for a customer and it would not perform well with the stock map.
We were running a C2 ignition with 4 maps and I placed a switch on the console so we could easily
try different maps. We kept getting better performance with more advance. After trying a number
of maps we achieved almost our desired performance with the map labeled “Switch Position 4”.

However, we found the bike was bogging down around the ton and we came up with the map labeled
“Switch Position 3”. This map is similar to the map Kenny Cummings developed for his race bike:

Since the bike did not have a fairing, reaching around 100 mph was putting a load on the engine as
if it was going up a steep hill. Load on an engine required the ignition to be retarded and, as you
can see, we achieved this from the above map. With this new map we achieved performance well over the
ton. The first map, "Switch Position 4", worked fine through the gears but at high speeds "Switch
Position 3" worked best.

This was a specifically built, all new, short stroke engine where the normal Commando engine appears
to work just fine with our stock maps.

If anyone has more questions you can call me at (253) 735-2375 or E-mail me at fred@oldbritts.com.

Fred Eaton

Click to expand...

Old Britts,
Is there a decent paper on this subject on the web somewhere ? I'm inclined to believe that the combination of the various Mikuni needles and a learning ignition system might give good results on a commando race bike. I run a lot of advance on my bike due to the methanol fuel, however I suspect it can tolerate a lot more further up the rev range depending on the jetting. It might help acceleration right up the usable rev range.

Jim, when you say your ignition system learns to adjust itself to avoid pinging, are you talking about it reshaping the curve or switching between alternative curves ?

hobot said:

I'm a bit current on knock sensors, narrow band and wide band and spectrum analysis principles to filter to apply to Peel so Jim has pulled off a tough task to get knock sensor to actually be useful in ignition protection in ringy dingy norton rather than just be fooled by normal engine sounds over 6000 rpm and retard unneeded. Jim's is a one in a row though but maybe our ear with head phone or LED could pick up ping while tuning to avoid it. i'd mount Peels in top center of head steady bolt hole.

Click to expand...

The pinking happens in the cylinder not the head Hobot. Now tell us the best place to put the sensor.

The above info from Old Britz is very good. Ii looks like they can program an ignition that wold be more suitable to a bigger range of requirements. This is the stuff I am looking for and I recommend any one else looking for a replacement ignition system to ask the same sort of questions. I realise we are getting technical but this is the modern age. I would love to see Commandos outperform modern bikes. I know they can be made to handle better than most of the big Four's etc. And Harleys are after all, tractors. [ Sorry HD ] I tell my friends in NZ that we have the roads for Norton's here in NZ [ just bloody rough and ready ], and The States has the roads for Harleys.

We have the Takaka hill etc. Some guys I know raced over the hill with their Brit Bikes and one welded his calipers to his disc just before he hit the bottom on the Takaka side. That's an 800 m drop strait down via a zig zag. A friend flew my round the coast where I live one time at 1500 feet [ 460 meters ]. I travelled from LA to Las Vegas on a bus one time and the driver said we had just reached 4000 feet, yet the road appeared nearly straight and with only a gentle slope. I was watching from the dickie seat on the right beside the driver. I think I pissed the Hostess off because she ended up sitting at the back.
I think Hobot will agree these bikes of ours are "Unapproachable'' in mountainous conditions.

kerinorton said:

The pinking happens in the cylinder not the head Hobot. Now tell us the best place to put the sensor.

Click to expand...

Plus the head contains the valve gear. The noise from it will overwhelm even the best filter. Jim

Duh, dudes, I'm half deaf from explosions but for the ones set off inside metal cylinders so know better than nay sayers about whats making the ping - ring sound in Commando's. Its not the explosion sound we hear pinging as much as the shock wave slap like a clapper in our bells. Tap a head on the bench with screw driver like drum stick and see what i mean. Then listen for this same ringy sound next time at idle. Best to wrap headers though as they ring-clang too with exhaust blast hits. The base line freq zone of engines whose heads don't ring like our bells is figured out by the volume of the combustion chamber dimensions just like musical instruments so listening at the top of the head is definitely a good place for knock sensor just not the only place as sound well conduced every where in our all metal engines. In many engines there is no difference at hi rpm form normal or ping sound freq so can be so tricky to filter most hi performance engines simple cut out the knock sensor above some rpm level. For JIm to have solved this is hard as rocket science.

I base what I do when tuning my commando on what we have done with our two stroke speedway sidecars using methanol. The leaner they get the faster they go until they become very expensive. Detonation usually occurs first where there is a squish band with a 'dead area'. The exercise has been to taper the squish band slightly to stop it. We always use standard fixed (petrol) ignition timing and comp. ratio, even though the methanol has superior antiknock properties. Trimming jetting to get the mixture right is difficult enough without introducing the extra variable. You will find that varying the ignition timing often gives the same symptoms as leaning off the jetting (disaster). With a programmable ignition timing the extra variable is still controlled. My Norton on methanol is excellent. I'm using 34mm MK2 Amals with Mikuni 6F needles with a 0.116 inch (from memory) needle jet with 670 Amal main jets and a No 3 slide, with standard compression and 32 degrees ignition advance. In getting to that I used a 0.117 inch needle jet and could not get the motor to cough by lowering the needle. With the 0.116 needle I was able to induce the cough by lowering the needle one notch from the centre position. The bike is really great in corners.
My contention is that I do not believe that the Mikuni 6F is the optimum right across the full range of throttle openings, things like that don't just happen. There is a multitude of tapers available in Mikuni needles. And it is obvious that there must also be an optimum in the way the ignition advance changes with the revs of the motor, and the gearing you eventually use for each race circuit to handle the difference in torque output.
I know what I've said relates to methanol fuel, however the exercise is the same when you do it with petrol as fuel, except that the fuel flow is approximately halved. - It is far more critical to get it right. A change in diameter of a petrol jet makes a much bigger difference. I would never race using petrol, it is too hard on the motor.

If you are getting signs of detonation occurring down inside the cylinder, that is crazy stuff. With that comment about the gas conversion, if you have to advance the ignition that far to get sense out of it, you are running it far too rich.

hobot said:

Duh, dudes, I'm half deaf from explosions but for the ones set off inside metal cylinders so know better than nay sayers about whats making the ping - ring sound in Commando's. Its not the explosion sound we hear pinging as much as the shock wave slap like a clapper in our bells. Tap a head on the bench with screw driver like drum stick and see what i mean. Then listen for this same ringy sound next time at idle. Best to wrap headers though as they ring-clang too with exhaust blast hits. The base line freq zone of engines whose heads don't ring like our bells is figured out by the volume of the combustion chamber dimensions just like musical instruments so listening at the top of the head is definitely a good place for knock sensor just not the only place as sound well conduced every where in our all metal engines. In many engines there is no difference at hi rpm form normal or ping sound freq so can be so tricky to filter most hi performance engines simple cut out the knock sensor above some rpm level. For JIm to have solved this is hard as rocket science.

Click to expand...

Hi Hobot, I think my tutors told us that it is the shock waves or vibrations that the knock sensor measures, not sound. [ we are talking over 30 years ago here so my memory may not be all that good. ]

Jim, I didn't realise you had so much variation in fuels over there, but your in a huge country. We have only ONE refinery in NZ, which feeds the big 4 { Shell, BP, Caltex [ Texaco to you guys ] and Mobil }. There are 2 independents Challenge and Gull who I think bring in their own fuel.
I use only Caltex and BP because the others require me to pay up front, and I never know how little fuel I need.

Acotrel. It was pig in the poke tuning in those days. The mixers used often were not up to the task. Impco ahd the best system which had a variable venture like a Stromberg cd carb. the others were fixed, and often had to set as rich as f... at cruise to get them to perform at lower revs and higher power requirements. The detonation in that Mitsubishi engine was caused by excessively over advanced ignition timing to help the CNG fuel do its job. When you run out of CNG, you turn over to petrol and then ruin you engine.