thank you, do i need to divide the rpm by 2?
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Ignition timing for modified engines
- Thread starter zrx1100
- Start date
No, in the program you enter the rpm and the advance or just pull the points with your mouse. When you get something you like program by pressing the tab up the top of the page and its done.
I have innogntion on the way. Looking forward to playing with programmable advance. Expect more dyno charts 
We're you able to find different tension springs anywhere?
Back in the day, cars used a combo set of springs to achieve the "step or dog legged" curve. Soft initial spring combined with a loose fitting stiffer rate spring to slow the rate of advance until the weights hit the max limit.
I have a Mallory spring kit for car diz, but they're much lighter than the 650 springs.
Back in the day, cars used a combo set of springs to achieve the "step or dog legged" curve. Soft initial spring combined with a loose fitting stiffer rate spring to slow the rate of advance until the weights hit the max limit.
I have a Mallory spring kit for car diz, but they're much lighter than the 650 springs.
So, I'm trying to understand this. XS650's, as far as I know, are not really "performance bikes". Yes of course there's the Kenny-esque 750's but they still don't produce today's horsepower. Hell, all of us have probably owned motorcycles that have 2x+ or 3x the HP of an XS650.
My XS-2 back in the day was not as fast as a CB750, but I wanted to pretend it was.
So ... I don't understand this discussion of advance curves. If you get the perfect advance curve, will it give you what, another 0.5 HP? Or better? Not trying to be a downer, just don't get it.?
My XS-2 back in the day was not as fast as a CB750, but I wanted to pretend it was.
So ... I don't understand this discussion of advance curves. If you get the perfect advance curve, will it give you what, another 0.5 HP? Or better? Not trying to be a downer, just don't get it.?
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There's a certain satisfaction making something OLD just work.
A higher level, is making it work optimally. Beyond that (inexplicably) is whipping all the other "Mitty's" butts with your antique. Its not logical, and maybe not ego driven. Its simply knowing you can do it.
We all own faster bikes. Its just fun.
A higher level, is making it work optimally. Beyond that (inexplicably) is whipping all the other "Mitty's" butts with your antique. Its not logical, and maybe not ego driven. Its simply knowing you can do it.
We all own faster bikes. Its just fun.
i did look into that. and ordered some springs as well. in the end it is was a bit of a challenge to find springs with not only with the target constant, but also the right preload. so to avoid a lot of trial and error, i looked for a programmable igition. @vexsed suggested innognition, which seems to be pretty impressive. @vexsed has had good success with these. I will see.
it is the journey
that said, on the dyno sheet, my bike keeps up with ducatis scrambler until ~ 6K rpm
https://www.xs650.com/threads/just-ride.54772/post-853241
what i will try to do is to put in more advance at 2200rpm to compensate for the poor mixture due to the timing of the pressure wave coming back withile valves overlap. Also, will retard the iginition a bit under load. Going uphil at part throttle my AFR is in mid 13s. Innognition allows for two curves and has a vacuum sensor.
I entirely agree for a road bike there is little to be gained.
I also have the opinion why not, some people me included like doing this sort of thing.
Keep us posted Zrx1100.
Yes, I think the answer is "because I can".
Objectively, to me, it makes no sense at all really chasing a fraction of a horsepower. But I have done it in the past. Because I could.
I put a lot of effort now into the near fifty year old bike hoping it will get me home again when I go out on it. That's a challenge enough.
Yes it's not just power but running well and efficiently at all operating RPMs a worthy goal?
it is the journey
that said, on the dyno sheet, my bike keeps up with ducatis scrambler until ~ 6K rpm
https://www.xs650.com/threads/just-ride.54772/post-853241
what i will try to do is to put in more advance at 2200rpm to compensate for the poor mixture due to the timing of the pressure wave coming back withile valves overlap. Also, will retard the iginition a bit under load. Going uphil at part throttle my AFR is in mid 13s. Innognition allows for two curves and has a vacuum sensor.
View attachment 365482
Thanks! Makes sense; nice dyno.
It will be interesting to see your results with the Innognition...to me, the biggest/best improvement might be the vacuum sensor's effect(?).
With a vac. sensor(MAP) everything is possible.it is the journey
that said, on the dyno sheet, my bike keeps up with ducatis scrambler until ~ 6K rpm
https://www.xs650.com/threads/just-ride.54772/post-853241
what i will try to do is to put in more advance at 2200rpm to compensate for the poor mixture due to the timing of the pressure wave coming back withile valves overlap. Also, will retard the iginition a bit under load. Going uphil at part throttle my AFR is in mid 13s. Innognition allows for two curves and has a vacuum sensor.
View attachment 365482
Software have 3D mapping?
For wide open throttle(WOT):
As i know, the mechanical advance stops short of detonation, just prior to peak pressure/torque.
It's way under advanced in the beginning of RPM sweeps, safe at peak torque and somewhat under advanced at higher RPM's.
Care to comment?
the ignition allows for two curves depending on threshold vacuum level. So not an extensive map
I finally had a chance to play with the Innognition setting on a dyno. The goal for me was to see if I could flatten a bit the dip in my torque at 2500rpm which comes from the exhaust wave reflection from the ends of the headers.
Reading https://www.smedspeed.co.uk/tech.html “IGNITION TIMING FOR MODIFIED ENGINES” a year ago, I came across something that makes perfect sense: poor mixtures due to exhaust wave reflection during overlap need more advance, modified motor need less total advance and the advance maximum should be reached further out, 3500rpm or so. That sent me on a path of trying different advance springs and ultimately settling on “Innognition” as this is the only option I found that would have a programmable curve and retain stock electrical system.
Innognition has a vacuum sensor for part-load advance, but since the dyno runs are wide open, I will focus only on the full load curves.
Here are the maps I tried. The original ignition advance I had was a Pamco with a mechanical advancer. There is quite a bit of uncertainty where the timing of the mechanical advance actualy is. In the graph below are the various maps with two mechanical advance curves in gray: one per the bike manual and the other, the more advanced one, is what I measured, also with high degree of uncertainty.
The curves are overlayed with the AFR mixture. The focus was to dial in advance in the region of poor mixture and then see what happens.
I succeeded somewhat to smooth out the torque curve around the 2500rpm dip.
Map 4(5) had least advance and clearly underperformed. Dialing in advance in the poor region stopped providing gain over the mechanical advance at map 4(6). Though it does not seem like much, the relative gain in the region of 2-3k rpm is close to 10% as the slope vs rpm is quite steep. Everywhere else the gains are small to none, other than at the higher rpm.
Here is the final result:
Plotted across rpm the gain in torque is noticeable around the dip.
The bike feels stronger and more responsive across the board and idles the best it ever did.
Below is the printout. Not sure what was going on with the wobble at high rpm, but this dyno does this sometimes.
The AFR plot shows that I can go down a size on the main and raise the needle. In fact, my strongest run with the mechanical advance was with one size smaller main and the needle raised a notch. I am not sure why I changed to the larger main back then, but now I think this accounts for the difference that I saw in my EPO/reverse cone comparison was due to this jetting change. So now I am back to the richer middle and the leaner main. For the ignition curve, I set the milder map 4(6) as it gives pretty much the same performance.
Maybe with these changes I can get closer to 54 hp. The next “big” project would be to add a cross-over tube and see if that flattens the torque, but I don’t want to give up the rush between 3 and 4k rpm
. Also can try to drop the oil sump…
Reading https://www.smedspeed.co.uk/tech.html “IGNITION TIMING FOR MODIFIED ENGINES” a year ago, I came across something that makes perfect sense: poor mixtures due to exhaust wave reflection during overlap need more advance, modified motor need less total advance and the advance maximum should be reached further out, 3500rpm or so. That sent me on a path of trying different advance springs and ultimately settling on “Innognition” as this is the only option I found that would have a programmable curve and retain stock electrical system.
Innognition has a vacuum sensor for part-load advance, but since the dyno runs are wide open, I will focus only on the full load curves.
Here are the maps I tried. The original ignition advance I had was a Pamco with a mechanical advancer. There is quite a bit of uncertainty where the timing of the mechanical advance actualy is. In the graph below are the various maps with two mechanical advance curves in gray: one per the bike manual and the other, the more advanced one, is what I measured, also with high degree of uncertainty.
The curves are overlayed with the AFR mixture. The focus was to dial in advance in the region of poor mixture and then see what happens.
I succeeded somewhat to smooth out the torque curve around the 2500rpm dip.
Map 4(5) had least advance and clearly underperformed. Dialing in advance in the poor region stopped providing gain over the mechanical advance at map 4(6). Though it does not seem like much, the relative gain in the region of 2-3k rpm is close to 10% as the slope vs rpm is quite steep. Everywhere else the gains are small to none, other than at the higher rpm.
Here is the final result:
Plotted across rpm the gain in torque is noticeable around the dip.
The bike feels stronger and more responsive across the board and idles the best it ever did.
Below is the printout. Not sure what was going on with the wobble at high rpm, but this dyno does this sometimes.
The AFR plot shows that I can go down a size on the main and raise the needle. In fact, my strongest run with the mechanical advance was with one size smaller main and the needle raised a notch. I am not sure why I changed to the larger main back then, but now I think this accounts for the difference that I saw in my EPO/reverse cone comparison was due to this jetting change. So now I am back to the richer middle and the leaner main. For the ignition curve, I set the milder map 4(6) as it gives pretty much the same performance.
Maybe with these changes I can get closer to 54 hp. The next “big” project would be to add a cross-over tube and see if that flattens the torque, but I don’t want to give up the rush between 3 and 4k rpm
. Also can try to drop the oil sump…
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Hotrods316
XS650 Enthusiast
This is cool! Thanks for sharing! That is a weird dip at 2-2500 rpm. (I’m no tuner but I can see weird stuff lol)
Glad you were able to smooth that out. And solid pulls to 7000rpm. This a street bike correct? Bet it feel nice on that pull with power
Glad you were able to smooth that out. And solid pulls to 7000rpm. This a street bike correct? Bet it feel nice on that pull with power
Basically timing is the inverse of torque, for best "curve".
WOT only.
WOT only.
I like to think of it as timing being an inverse of the intake quality curve. AFR is a somewhat of a proxy of that. So I tried to get more timing in where I have a poor mixture at 2500 rpm, then reduce the rate of advance increase through the peak in the torque and the lean section of the AFR.
I am going to try reducing the timing even more between 3-4K and then bringing it back up at 5K.
I did try the currve below, but the bike did not like it: too much advance at 2500 rpm. this curve is from Asuotani https://www.xs650.com/threads/asuotani-ignition.70019/
I am going to try reducing the timing even more between 3-4K and then bringing it back up at 5K.
I did try the currve below, but the bike did not like it: too much advance at 2500 rpm. this curve is from Asuotani https://www.xs650.com/threads/asuotani-ignition.70019/
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