Buzz Killl?
- Thread starter Ben70_imp
- Start date
Hello Ben, thanks for the great write-up. Your conclusion is that you have reduced the vibration significantly (I added "significantly", based on your comments). I am not doubting your results, but I would like to understand better exactly how such a minor change resulted in such a significant reduction in vibration. I studied dynamics of machinery, back during my college days, and I am not claiming to be an expert in this field (far from it), but if you could please provide an explanation (please don't hesitate to get technical because I think a lot of the guys who visit this site are really intelligent), I would really be interested to read it - and possibly learn something. Thank you.
Hi Dave! The physical difference in the intake cam is simply shorter duration on 1 and 2 cylinders by 10 degrees. Intake valves close 38 degrees after bottom dead center for 3-4, 28 after for 1-2. I really don't know why this produces a different tone or note to the exhaust, which with my Yosh exhaust was notable, and went away after I put the exhaust cam on the intake side. It still has a nice sound, but it sounds to me more relaxed and comfortable with what it's doing, rather than urgent and forced, or fierce.
The sound was possibly what they were going for, but what also went away was the harmonic buzz. Different than a vibration, which I believe is what you get with an inline 4.
Many either don't feel it or are not bothered by it. When my wife asked me why I was taking apart a perfectly good motorcycle and I explained it, she said " Your hands go to sleep when you watch NCIS". Hah.
But if you have the bike on it's sidestand and increase rpms steadily you may note that as you pass through 2800-3300 rpm it changes from vibration to vibration and buzz, which bothered me after a relatively short ride. Often used my throttle lock/ cruise control to free up my hand long enough to get the feeling back.
I also found that I was not as aware of the rpms. I found myself forgetting to shift into 5th.
So I can't really explain in technical terms but apparently there is a frequency that causes it. I was worried that I would get a "normal" cam on the intake side and it would still have it, but it does not. Vibration, yes. Harmonic buzz, no.
I found a cam guy that isn't sure if I knew what I was talking about because I think he just couldn't process the concept of altering a cam like that for purposes other than performance. He agreed to have a look at it and whenever that shakes out I will give him credit if everything works out.
Ben
The sound was possibly what they were going for, but what also went away was the harmonic buzz. Different than a vibration, which I believe is what you get with an inline 4.
Many either don't feel it or are not bothered by it. When my wife asked me why I was taking apart a perfectly good motorcycle and I explained it, she said " Your hands go to sleep when you watch NCIS". Hah.
But if you have the bike on it's sidestand and increase rpms steadily you may note that as you pass through 2800-3300 rpm it changes from vibration to vibration and buzz, which bothered me after a relatively short ride. Often used my throttle lock/ cruise control to free up my hand long enough to get the feeling back.
I also found that I was not as aware of the rpms. I found myself forgetting to shift into 5th.
So I can't really explain in technical terms but apparently there is a frequency that causes it. I was worried that I would get a "normal" cam on the intake side and it would still have it, but it does not. Vibration, yes. Harmonic buzz, no.
I found a cam guy that isn't sure if I knew what I was talking about because I think he just couldn't process the concept of altering a cam like that for purposes other than performance. He agreed to have a look at it and whenever that shakes out I will give him credit if everything works out.
Ben
It's taken me a while to find this again, but the quote from the Honda Designers Talk propaganda back in the day was:
Quote:Sekiya:
On the hardware side, phased valve timing gives the engine its characteristic feel around the 3,000 rpm range. How did you create the engine's personality?
Minami:
Basically, straight-four engines run smooth as long as all four pistons move the same way. My initial thoughts were, to give the engine a deep rumble, we'd have to change the movement a bit.
We ended up shifting the valve timing of cylinders 1 and 2, compared to cylinders 3 and 4, and by continuing to change the gap, found the right combustion out-of-sync feel.
Sekiya:
Valve timing is usually changed or made variable to increase output, but your aim was completely different. Maybe the exact opposite of conventional wisdom.
Minami:
Precisely. We took the opposite approach to conventional thinking, so we weren't sure if it would work.
Quote:Sekiya:
On the hardware side, phased valve timing gives the engine its characteristic feel around the 3,000 rpm range. How did you create the engine's personality?
Minami:
Basically, straight-four engines run smooth as long as all four pistons move the same way. My initial thoughts were, to give the engine a deep rumble, we'd have to change the movement a bit.
We ended up shifting the valve timing of cylinders 1 and 2, compared to cylinders 3 and 4, and by continuing to change the gap, found the right combustion out-of-sync feel.
Sekiya:
Valve timing is usually changed or made variable to increase output, but your aim was completely different. Maybe the exact opposite of conventional wisdom.
Minami:
Precisely. We took the opposite approach to conventional thinking, so we weren't sure if it would work.
:rofl:
Hi Ben, thank you for your reply. It's pretty easy to understand why the sound would be different. I am sure it's a very complicated mix of vibrations within the engine, coming from various sources, that result in the vibration you feel at the handlebars. Somehow the different geometry of the replaced camshaft affected how all these forces work together, and the result is you feel less vibration. I was hoping for a good technical explanation, but I understand if you don't have one. There's a lot of really sharp people who visit this forum, and maybe one of them will take the time to post a good explanation. I would really like to know how our bikes would run (increased hp, less vibration?) if the cam lobes were the same for all cylinders. Good luck with your experimentation, and please keep us informed of your results.
In the engineers’ talk quoted above it’s hard to know whether the ‘rumble’ Minami is talking about is aural or tactile. I assumed the former, but who’d know.
Just addressing the topic of exhaust noise, when I got my CB the original owner had installed the full Yosh exhaust system. The salesman revved it in the parking lot and it popped, which he apparently thought was a cool selling point.
I told him I'd buy it if the stock exhaust came with it. Next day the stock exhaust had magically been unearthed, I bought the bike and the stock exhaust is still hanging in my shed. I disabled the PAIR and the popping on decel diminished drastically but it still did it on downhill deceleration.
As the popping is caused by unburnt fuel igniting in the exhaust, it is not a surprise that premium fuel, which burns at a slower rate, makes it worse. Or better if you like popping. It is also an indication that this engine was designed to run on regular fuel as recommended.
An interesting thing about the modification of installing the exhaust cam on the intake side is the noise on downhill decel changed to a muted burble. So the fuel mix is being burned more efficiently. I suspect it is because it doesn't get as much fuel to begin with, because of the difference in cam profile, as also indicated by the reduction in hp on the dyno.
SO, the snarl went away and the popping went away, the things that were supposed to be desirable traits by the design team and the used bike salesman. I suspect some of both may come back when I get my finished product in place. I am waiting for the cam man to receive my cam so I can find out what he thinks. Also waiting to hear from Guhl on my computer. So I have bike parts spread all over the country in the midst of a global shutdown. Fingers crossed.
As a side note on exhaust noise, Google Mini Cooper exhaust burble, the forums are funny as heck (to me).
Ben
I told him I'd buy it if the stock exhaust came with it. Next day the stock exhaust had magically been unearthed, I bought the bike and the stock exhaust is still hanging in my shed. I disabled the PAIR and the popping on decel diminished drastically but it still did it on downhill deceleration.
As the popping is caused by unburnt fuel igniting in the exhaust, it is not a surprise that premium fuel, which burns at a slower rate, makes it worse. Or better if you like popping. It is also an indication that this engine was designed to run on regular fuel as recommended.
An interesting thing about the modification of installing the exhaust cam on the intake side is the noise on downhill decel changed to a muted burble. So the fuel mix is being burned more efficiently. I suspect it is because it doesn't get as much fuel to begin with, because of the difference in cam profile, as also indicated by the reduction in hp on the dyno.
SO, the snarl went away and the popping went away, the things that were supposed to be desirable traits by the design team and the used bike salesman. I suspect some of both may come back when I get my finished product in place. I am waiting for the cam man to receive my cam so I can find out what he thinks. Also waiting to hear from Guhl on my computer. So I have bike parts spread all over the country in the midst of a global shutdown. Fingers crossed.
As a side note on exhaust noise, Google Mini Cooper exhaust burble, the forums are funny as heck (to me).
Ben
CAUTION! If you are considering this mod please hold off until I can determine if injector timing was also staggered. This was one of PowerDubs concerns along with ignition timing.
I have two indications that this may be the case. First, there is a rapid surge at idle after the engine is warm. I didn't notice this right away, partly because it doesn't do it cold and it is not huge, but it is consistent.
Second, there is a lean spot during acceleration when compared to the initial dyno run. Not toward the higher rpm.
I need to compare injector pulse widths, probably on one and four since they would be easiest to access.
Should have done that first. I suspect the Guhl flash may not be capable of altering individual pulse width, but I don't want to ask until I know that is what is happening.
So I need to locate a scope. A lab scope would work, or some automotive scopes.
I guess it was willful thinking that they wouldn't mess with pulse width, but why not?
On the other hand, it is only a 10 degree difference in 228 to 238. It doesn't seem like enough of a percentage to make a noticeable difference, less than 5%. Will have to check it out.
Ben
I have two indications that this may be the case. First, there is a rapid surge at idle after the engine is warm. I didn't notice this right away, partly because it doesn't do it cold and it is not huge, but it is consistent.
Second, there is a lean spot during acceleration when compared to the initial dyno run. Not toward the higher rpm.
I need to compare injector pulse widths, probably on one and four since they would be easiest to access.
Should have done that first. I suspect the Guhl flash may not be capable of altering individual pulse width, but I don't want to ask until I know that is what is happening.
So I need to locate a scope. A lab scope would work, or some automotive scopes.
I guess it was willful thinking that they wouldn't mess with pulse width, but why not?
On the other hand, it is only a 10 degree difference in 228 to 238. It doesn't seem like enough of a percentage to make a noticeable difference, less than 5%. Will have to check it out.
Ben
PowerDubs_imp
Road warrior
Glad to see someone else not afraid to rip into the engine.
Sorry to hear you are having issues.
My suggestion to anyone going beyond a slip on exhaust- is a Dynojet power commander and the auto tune box. Even if you get a guhl ecu.
Having the ecu be able to monitor a wideband O2 and constantly actually adjust to your specific bike, in every weather and altitude is the right way to go. It changes the fuel for all throttle positions, all rpm.
Sent from my iPhone using Tapatalk
Sorry to hear you are having issues.
My suggestion to anyone going beyond a slip on exhaust- is a Dynojet power commander and the auto tune box. Even if you get a guhl ecu.
Having the ecu be able to monitor a wideband O2 and constantly actually adjust to your specific bike, in every weather and altitude is the right way to go. It changes the fuel for all throttle positions, all rpm.
Sent from my iPhone using Tapatalk
Thanks for the tip, Josh. And for documenting your work, it is very helpful.
My idea was to find out the least I could do to get rid of the buzz, and just using the ex. cam on the intake side seemed do-able. The Guhl flash was incidental, I was wanting to do that anyway.
The idle issue is inconsistent, I hope to see whether or not fuel injector timing is even soon. I did hold it at 2500 rpm for a couple minutes and checked the head pipes with a pyrometer. It was within 5 degrees on 2,3, and 4, and between 5 and 10 degrees warmer on #1, so if it is lean it doesn't look bad enough to cause trouble and ran great on my ride today.
Will keep you posted on the cam situation
Ben
My idea was to find out the least I could do to get rid of the buzz, and just using the ex. cam on the intake side seemed do-able. The Guhl flash was incidental, I was wanting to do that anyway.
The idle issue is inconsistent, I hope to see whether or not fuel injector timing is even soon. I did hold it at 2500 rpm for a couple minutes and checked the head pipes with a pyrometer. It was within 5 degrees on 2,3, and 4, and between 5 and 10 degrees warmer on #1, so if it is lean it doesn't look bad enough to cause trouble and ran great on my ride today.
Will keep you posted on the cam situation
Ben
PowerDubs_imp
Road warrior
If you don't mind, I actually would like to see the dyno charts.
Here it is, PD...
Hope you can see it. The blue line is stock, with flat torque curve, strong, linear hp gain to what I assume is rpm cut out and mixture leaning a bit in midrange from stock and more, relatively at higher hp.
The other lines show leaner running across the board, torque diminishing with rpm and I asked him to cut it when it stopped making power, never did reach limiter. All done in 3rd gear.
Surprisingly, it feels good. Probably because in normal riding I don't get above 4 to 4500 rpm and passing power is good.
This was before the reflash, I will post new results with flash and a different cam profile soon. Also need to check my injector timing question. If it can't be brought closer to "normal" I will go back to the stock cam and live with the buzz, chalk it up to research. But it feels so nice I hope it can be made better. without a NASA style budget.
Ben
Hope you can see it. The blue line is stock, with flat torque curve, strong, linear hp gain to what I assume is rpm cut out and mixture leaning a bit in midrange from stock and more, relatively at higher hp.
The other lines show leaner running across the board, torque diminishing with rpm and I asked him to cut it when it stopped making power, never did reach limiter. All done in 3rd gear.
Surprisingly, it feels good. Probably because in normal riding I don't get above 4 to 4500 rpm and passing power is good.
This was before the reflash, I will post new results with flash and a different cam profile soon. Also need to check my injector timing question. If it can't be brought closer to "normal" I will go back to the stock cam and live with the buzz, chalk it up to research. But it feels so nice I hope it can be made better. without a NASA style budget.
Ben
max
Road warrior
Ben on the subject of scopes you probably already know this but on the offchance here is a guy with a 4 chan picoscope specifically for automotive applications that demontrates in some detail what you may want to do.
In addition to pulse with variation Honda may possibly alter the individual timing as well, i don't know this but without a degree scale this may not be obvious or easy to find, just an idea.
Do you happen to know if this timing " buzz " was inplemented from the getgo or was it introduced at some later point?
Interesting stuff you're doing.
In addition to pulse with variation Honda may possibly alter the individual timing as well, i don't know this but without a degree scale this may not be obvious or easy to find, just an idea.
Do you happen to know if this timing " buzz " was inplemented from the getgo or was it introduced at some later point?
Interesting stuff you're doing.
Check out post #24. Looks like they wanted to give it some rumble, growl or whatever. It does sound pretty fierce when it gets that noise going on acceleration.
The lack of an urgent feeling at certain rpm's is hard to explain. When I mentioned "harmonic dissonance" in an earlier post, Dave asked for a technical mechanical explanation, which I don't have.
However, I Googled it, and found a lot of music references. Comparing chords and sound waves that intersect at even or uneven spots. Apparently it can be used as a musical device to provoke anticipation, or disquiet. I urge you to check it out, it kind of describes that feeling I get of "shift me , or make me go faster" that I feel in stock mode.
Interesting that that feeling is reduced with the higher gearing of a 19 tooth front sprocket and even more with the smaller rear sprocket, and may be why those with a six speed seem less likely to have a problem with it.
The term may have been used on me at an early age when violin lessons were inflicted upon me.
Ben
The lack of an urgent feeling at certain rpm's is hard to explain. When I mentioned "harmonic dissonance" in an earlier post, Dave asked for a technical mechanical explanation, which I don't have.
However, I Googled it, and found a lot of music references. Comparing chords and sound waves that intersect at even or uneven spots. Apparently it can be used as a musical device to provoke anticipation, or disquiet. I urge you to check it out, it kind of describes that feeling I get of "shift me , or make me go faster" that I feel in stock mode.
Interesting that that feeling is reduced with the higher gearing of a 19 tooth front sprocket and even more with the smaller rear sprocket, and may be why those with a six speed seem less likely to have a problem with it.
The term may have been used on me at an early age when violin lessons were inflicted upon me.
Ben
PowerDubs_imp
Road warrior
Thanks for the chart.
I am on my phone but will take a look later.
What else have you done besides the cams?
Any sort of exhaust or intake work?
Completely stock air & fueling?
02 sensor bypass or pair delete?
Sent from my iPhone using Tapatalk
I am on my phone but will take a look later.
What else have you done besides the cams?
Any sort of exhaust or intake work?
Completely stock air & fueling?
02 sensor bypass or pair delete?
Sent from my iPhone using Tapatalk
Hi PD! PAIR plugged, O2 bypass, full Yosh exhaust. Running stock sprockets. The Yosh was on when I got it but PAIR was intact and it popped. Don't plan on other mods, but the fueling enhancements you suggest have me intrigued. Even with mismatched pulse widths a happy medium may be achievable. I hope to know more in the coming week.
Just checked ignition timing on 1&4 is the same. So that's confirmed anyway.
Ben
Just checked ignition timing on 1&4 is the same. So that's confirmed anyway.
Ben
PowerDubs_imp
Road warrior
I'm interested in seeing what you continue to experience with further work.
Did you happen to ask for the actual run file from the dyno operator? ( .drf file). If not- they can email it to you as it is only kb.
I just bring a thumb drive with me whenever I dyno a car or bike.
I haven't touched my bike since I crashed, but given this stuck at home bs, I probably will drag it out when I run out of yard work and start replacing the scraped up bits. I already have the pieces.
I never got to dyno with the Guhls ecu, heck- only got to ride it for maybe 10 minutes. But I do want to redyno to see what's what.
For reference, if you haven't seen it- but you probably have, here is where I am at from last time- http://cb1100forum.com/forum/showthread.php?tid=9608&pid=215843#pid215843
I would def richen up your fueling. If you decide to do the dynojet power commander and auto tune- you can also put a configurable dash on so you can keep an eye on it in real time- https://www.dynojet.com/power-commander-pod-300-display/
Did you happen to ask for the actual run file from the dyno operator? ( .drf file). If not- they can email it to you as it is only kb.
I just bring a thumb drive with me whenever I dyno a car or bike.
I haven't touched my bike since I crashed, but given this stuck at home bs, I probably will drag it out when I run out of yard work and start replacing the scraped up bits. I already have the pieces.
I never got to dyno with the Guhls ecu, heck- only got to ride it for maybe 10 minutes. But I do want to redyno to see what's what.
For reference, if you haven't seen it- but you probably have, here is where I am at from last time- http://cb1100forum.com/forum/showthread.php?tid=9608&pid=215843#pid215843
I would def richen up your fueling. If you decide to do the dynojet power commander and auto tune- you can also put a configurable dash on so you can keep an eye on it in real time- https://www.dynojet.com/power-commander-pod-300-display/
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