Programmable ignition timing

acotrel · Jul 8, 2014

Glen, Your comment :
'I was definitely in the market for programmable ignition for my non Norton project bike which has full race cams, 10.5 to one compression and Australian V8 super car style heads, etc etc. With all of the engine mods it is impossible to know what advance curve will suit the engine without experimentation.'

When you mention 'experimentation' do you mean dyno response or on-track ? I find it difficult enough coordinating gearing and tuning without playing with the programmable advance curve. Have you ever gone in this direction ? I know I can start in the middle and work from there, however if you have an on-track systematic approach, I would like very much to hear it.

worntorn · Jul 8, 2014

Alan, I am planning to pay for some dynomometer time to play with ignition timing and valve timing, but not carburetion. I've welded in a bung for an O2 sensor in the exhaust, so that will be used to get the mixture right and hopefully avoid any melted pistons.

Glen

Hobot · Jul 8, 2014

Besides power the EGT is also used to get spark right so might consider fitting CHT plug rings and EGT header needles to help optimalize. Once set don't need senors so can pass along to others or re-use on next engine changes. Pay attention to the thermal stain on hook electrode which should show up just before the bend. Timing is supposed to be set well before one diddles mixture. Norton dyno shops say best power shows close to 1400' F EGT and bit over 400'F head. Peel WOT showed 1375' F & 425'F head with 28-29' full adv but only 1200's EGT and 325'F head to hold the ton at rather less than WOT. That was with analog boyah set to just didn't back fire kicking then checked by light.

worntorn · Jul 8, 2014

Steve, my Timing changes on the dyno will be incremental. The curve is already preset for 28 degrees Max advance, this after much discussion between the owner of Pazon, UK racer Roy Robertson and other knowledgeable folk. I might shift it a couple of degrees one way or the other if the dyno indicates improvement. Much more than that and the start position will be off too much.

acotrel · Jul 8, 2014

I was always under the impression that 'pinking' occurred at low revs, wide throttle and heavy loads. From what Jim Comstock has said, his system retards slightly at high revs, similar to 70s two strokes to stop detonation. I haven't increased the comp. ratio on my 850. Running methanol, I keep it as lean as possible right down the needle using fixed advance of 32 degrees. It responds extremely well, and I don't believe it would ever ping on methanol. My question is about what conditions cause burning or detonation. I suspect I can run much more advance in the low to mid-range revs as long as the timing retards enough to allow max revs on long straights without causing damage ? There must be someone who has played with this previously ? I note the comment that Jim Schmidt has written about programming Boyer ignitions - what is the publication ?

Hobot · Jul 8, 2014

Most commonly detonation occurs on hi throttle lower rpm higher gears as time for pressure and radiation to over shoot BANG but can also happen near torque peak with highest filling rate and faster ignition of tighter packed mixture, unless spark comes a bit later.

comnoz · Jul 8, 2014

acotrel said:
I was always under the impression that 'pinking' occurred at low revs, wide throttle and heavy loads. From what Jim Comstock has said, his system retards slightly at high revs, similar to 70s two strokes to stop detonation. I haven't increased the comp. ratio on my 850. Running methanol, I keep it as lean as possible right down the needle using fixed advance of 32 degrees. It responds extremely well, and I don't believe it would ever ping on methanol. My question is about what conditions cause burning or detonation. I suspect I can run much more advance in the low to mid-range revs as long as the timing retards enough to allow max revs on long straights without causing damage ? There must be someone who has played with this previously ? I note the comment that Jim Schmidt has written about programming Boyer ignitions - what is the publication ?

I retard the timing at higher RPM to increase power and decrease the amount of heat loss to the piston. Pinging at high RPM is difficult to detect and by the time it is showing telltale signs on the spark plug you are well past minimum timing for best torque.

At minimum timing for best torque the heat loss into the engine is also at it's minimum.

Timing that is a little too fast pumps extra heat into the piston and timing that is a bit too slow puts extra heat into the exhaust valve and port.

Timing can be retarded a bit at high RPM because the increased turbulence in the combustion chamber makes for a faster burn. Jim

acotrel · Jul 9, 2014

'At minimum timing for best torque the heat loss into the engine is also at it's minimum. '

An interesting comment when you are using methanol which runs very cold and hides up the tuning errors, and has unlimited antiknock. I take your point, and recognise the same must apply regardless of the fuel.
I've long stayed away from racing modern bikes. I know they are excellent however all that happens in racing one is a quantam leap in speeds. Everything simply moves up a notch however the same handling difficulties still apply. The way I ride is to push the bike to the limit, find out where it is and then stay just inside it. I believe in some ways using methanol fuel instead of petrol is a bit like that. Are you permitted to use methanol under AHRMA rules or any other in the States ?

comnoz · Jul 9, 2014

acotrel said:
'At minimum timing for best torque the heat loss into the engine is also at it's minimum. '

An interesting comment when you are using methanol which runs very cold and hides up the tuning errors, and has unlimited antiknock. I take your point, and recognise the same must apply regardless of the fuel.
I've long stayed away from racing modern bikes. I know they are excellent however all that happens in racing one is a quantam leap in speeds. Everything simply moves up a notch however the same handling difficulties still apply. The way I ride is to push the bike to the limit, find out where it is and then stay just inside it. I believe in some ways using methanol fuel instead of petrol is a bit like that. Are you permitted to use methanol under AHRMA rules or any other in the States ?

No Methanol over here. [darn]

Hobot · Jul 9, 2014

i bet in the tighter turns where Commando still in power band your 850 Sleeley would give anything but Ms Peel a run for the money with the moderns likely needing more skill to keep up with ya.

I watched the ancient racer video you put up and wonder if a programmable ignition could be set up to mimic the nasty pops puffs and barks of short open pipe Indians for some fun around gathering places and maybe some back fire flames too!

Skip to 2:45 m to savor to rough and ready sounds
https://www.youtube.com/watch?v=vYYQUz3bjiI

acotrel · Jul 10, 2014

When I watched that video of on-board the Indian, I got a real adrenalin rush. I don't think many guys know just how scary that old stuff used to be. I had visions of that heavy old bike jumping on me. Also, no substantial helmets - no wonder a lot of guys met their ends doing that stuff back then. The old jiggers were not really slow. I've ridden sidecars on the speedway, - not a place to crash.

38 years ago :

SteveA · Jul 10, 2014

hobot said:
I watched the ancient racer video you put up and wonder if a programmable ignition could be set up to mimic the nasty pops puffs and barks of short open pipe Indians for some fun around gathering places and maybe some back fire flames too!

Hobot, you have ridden a Harley right?

They do something with their 'programmable ignition' which gives plenty of pops and bangs and stuff to give it that 'vintage' feel.....

Or they did on the two I rented to tour on, in California and New England..... :?

acotrel · Jul 10, 2014

I think Harleys are some of those things that are so bad that they are good. I really liked the XR750 road racer that Don Emde brought to Melbourne in about 1970. It was quite a good thing. Pity they didn't persevere and build the motor into a decent frame. The S1 Buell seemed to be on the right track. I believe the sporster based motor became quite good, even ended up with 5 speeds - you can actually do something with that. Pity the races were never classed on basic machine type and capacity. I'd love to race something like an XR750, however if the grid is also full of two strokes - forget it. I think it would be interesting to race the 750 commando against the XR750 Harley - might be great fun.

Hobot · Jul 10, 2014

In north Florida I got to use a big ole Red Indian Chief in the 70's on and off road a few year but it wasn't so mean sounding as those flat trackers and during P!! era which didn't sound so rough but would startle people by its meaness if blipped near by. I've tried out a hot rod 88 cid low bar cafe'd Harley with open pipes but most sound like old chevy V8 with glass packs and not really that quick and felt tractory to tour on as couldn't lean over much for twisties use.

chasbmw · Jul 12, 2014

hobot said:
Black box boyah users might get Jim Schimdt's Race Book as he explains how to change the curve/slope of these for racer acceleration out of turns. Good success on your expensive stab in the dark Wortorn.

So how do you program a Boyer?

I can't see any way of doing it unless you take the thing to bits.

The Boyer ignition curve for BMW airheadswas designed to damp down pinging in the 600cc models and so retarded the ignition curve between 2500 and 3000 revs. This was a micro digital curve I got from Boyer some time ago

http://i46.photobucket.com/albums/f146/ ... ngcurv.jpg

acotrel · Jul 12, 2014

I haven't seen a programmable boyer yet - mine is fixed timing. There must be provision to run a laptop against the new ones ?

Hobot · Jul 12, 2014

Well Jim Schmidt knows how to alter analog boyah externally to out response Triumphs & BSA's with same boyah - if ya get his Norton Commando Race Book.

Programmable ignition timing

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