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Discussion Starter #1
An experiment: Tuning out last of "shaking" via throttle grip metrics and PC V Map

An experiment: Tuning out last of the "shaking" via throttle grip metrics and PC V Map

Many of you know that I am currently working to eliminate the last of the "shaking" that the VTX 1800 commonly exhibits in the 1800 to 2300 rpm range, especially when there have been exhaust and intake changes made.

I have had the bike dyno tuned via Power Commander V ("PC V"), which made a big difference, but did not eliminate the shaking entirely. Micah Shoemaker, my dyno tuner, explained that tuning in that rpm range on the VTX via normal 4-gas method does not seem to work as well as it should (worked well every other rpm range), probably because there is an exhaust or intake resonance. Even the Cobra "PowrPro" autotuner was unable to eliminate it - the Cobra PowrPro exhibited notable loss of control of AFR in that range. Micah suggested I "hand tune" by manually modifying the Power Commander V fuel map manually via road test based trial and error.

The first step was to "calibrate" the throttle grip so that I could know what % throttle I was applying at all times. By doing so, I could know, every time I got the shaking, exactly what combination of engine rpm and % throttle it was occurring at.

The following photo shows how I did this:


The concept is simple. I put a piece of masking tape (masking tape as sued by painters, so that it can later be removed without a permanent residue being left in place) on the grip itself, and marked a "pointer" in ink on it, at a point that could easily be seen when riding the bike. I then also put a piece of masking tape on the grip housing, with a zero to 100% scale that could easily be viewed when riding the bike. By using these 2 pieces of tape, I know exactly what percent throttle I am applying when the shaking occurs. My Cobra tachometer gives me the engine rpm. So, I now have both rpm and % throttle.

As I discover rpm / %throttle combinations that exhibit shaking, I hold the combination as long as road grade and wind conditions allow to verify it is non-transient, and make notes on a notepad I carry. When I get home, I fire up my PC V software, and modify the fuel map to try to reduce or ideally eliminate the shaking at that point.

What has been working is richening the air fuel mixture at that point. You do this by increasing the percent of fuel increase within the body of the PC V fuel map, at that specific combination of rpm and % throttle. As you address more and more of these, the shaking becomes less and less frequent. This makes sense, because virtually all modern bike engines run lean from the factory for emissions reasons, and aftermarket exhaust and intake makes things worse due to more airflow beyond factory airflow. In the one book I have found devoted specifically to MOTORCYCLE engine EFI tuning, the author uses a Yamaha example where the mixture needed to be richened by a full 15% with STOCK exhaust and intake, in order to run like it should.

I now have gotten to the point where the shaking is almost entirely gone. It occurs now only specifically within a range centered on 2250 rpm and 20% throttle. It is detectable, although with far less intensity, as low as 2000 rpm and as high as 2500 rpm, and within the 15% to 25% throttle range only. It does not exhibit at all in normal level road cruising without notable headwind, but manifests only on uphills, headwinds or acceleration, because normal cruising at 50 to 55 mph in 4[SUP]th[/SUP] or 5[SUP]th[/SUP] gear does not require getting up to 20% throttle. Once I hit the 20% throttle range, I can still feel the shaking, although greatly attenuated from before. This appears to be the sole remaining sore spot.

So, last night, I richened that remaining range just a bit more (5% more), and will see this Saturday if it makes the necessary difference. (It is way too hot now here in Texas to go riding after work on weekdays - 98 to 102 degrees typically).

I have noted that the largest % increase in fuel that I need to apply was 42%! That needed to be applied to only 2 or 3 cells, but naturally tapering was required from there back down to the lower percentages developed around those points, on the dyno.

I'll let everyone know how this latest change works out, next weekend (unless it rains).

Jim G
 

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Good work

An experiment: Tuning out last of the "shaking" via throttle grip metrics and PC V Map

Many of you know that I am currently working to eliminate the last of the "shaking" that the VTX 1800 commonly exhibits in the 1800 to 2300 rpm range, especially when there have been exhaust and intake changes made.

I have had the bike dyno tuned via Power Commander V ("PC V"), which made a big difference, but did not eliminate the shaking entirely. Micah Shoemaker, my dyno tuner, explained that tuning in that rpm range on the VTX via normal 4-gas method does not seem to work as well as it should (worked well every other rpm range), probably because there is an exhaust or intake resonance. Even the Cobra "PowrPro" autotuner was unable to eliminate it - the Cobra PowrPro exhibited notable loss of control of AFR in that range. Micah suggested I "hand tune" by manually modifying the Power Commander V fuel map manually via road test based trial and error.

The first step was to "calibrate" the throttle grip so that I could know what % throttle I was applying at all times. By doing so, I could know, every time I got the shaking, exactly what combination of engine rpm and % throttle it was occurring at.

The following photo shows how I did this:


The concept is simple. I put a piece of masking tape (masking tape as sued by painters, so that it can later be removed without a permanent residue being left in place) on the grip itself, and marked a "pointer" in ink on it, at a point that could easily be seen when riding the bike. I then also put a piece of masking tape on the grip housing, with a zero to 100% scale that could easily be viewed when riding the bike. By using these 2 pieces of tape, I know exactly what percent throttle I am applying when the shaking occurs. My Cobra tachometer gives me the engine rpm. So, I now have both rpm and % throttle.

As I discover rpm / %throttle combinations that exhibit shaking, I hold the combination as long as road grade and wind conditions allow to verify it is non-transient, and make notes on a notepad I carry. When I get home, I fire up my PC V software, and modify the fuel map to try to reduce or ideally eliminate the shaking at that point.

What has been working is richening the air fuel mixture at that point. You do this by increasing the percent of fuel increase within the body of the PC V fuel map, at that specific combination of rpm and % throttle. As you address more and more of these, the shaking becomes less and less frequent. This makes sense, because virtually all modern bike engines run lean from the factory for emissions reasons, and aftermarket exhaust and intake makes things worse due to more airflow beyond factory airflow. In the one book I have found devoted specifically to MOTORCYCLE engine EFI tuning, the author uses a Yamaha example where the mixture needed to be richened by a full 15% with STOCK exhaust and intake, in order to run like it should.

I now have gotten to the point where the shaking is almost entirely gone. It occurs now only specifically within a range centered on 2250 rpm and 20% throttle. It is detectable, although with far less intensity, as low as 2000 rpm and as high as 2500 rpm, and within the 15% to 25% throttle range only. It does not exhibit at all in normal level road cruising without notable headwind, but manifests only on uphills, headwinds or acceleration, because normal cruising at 50 to 55 mph in 4[SUP]th[/SUP] or 5[SUP]th[/SUP] gear does not require getting up to 20% throttle. Once I hit the 20% throttle range, I can still feel the shaking, although greatly attenuated from before. This appears to be the sole remaining sore spot.

So, last night, I richened that remaining range just a bit more (5% more), and will see this Saturday if it makes the necessary difference. (It is way too hot now here in Texas to go riding after work on weekdays - 98 to 102 degrees typically).

I have noted that the largest % increase in fuel that I need to apply was 42%! That needed to be applied to only 2 or 3 cells, but naturally tapering was required from there back down to the lower percentages developed around those points, on the dyno.

I'll let everyone know how this latest change works out, next weekend (unless it rains).

Jim G

Jim, We have the same idea. I used pencil on my throttle with the PCIII software as my guide. What cells are you playing with? I would be glad to give you a rough A/F for those cells with my widebands using my bike as a rule of thumb. I am working out the last kinks of the Rostra cruise control install (yeah my FI popped with VSS and Rear Injector codes - but it works).
 

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Discussion Starter #3
Jim, We have the same idea. I used pencil on my throttle with the PCIII software as my guide. What cells are you playing with? I would be glad to give you a rough A/F for those cells with my widebands using my bike as a rule of thumb. I am working out the last kinks of the Rostra cruise control install (yeah my FI popped with VSS and Rear Injector codes - but it works).

Our physical setup is likely different. I have the Vance & Hines Staggered Big Shots as exhaust and the Forcewinder air intake PLUS an air filter on that Forcewinder that is pretty much exactly 200% the surface area of the stock air filter and way bigger than the surface area of the Forcewinder's normal air filter (On the dyno, the larger filter by itself with no other change added 2 rwhp over that of the normal Forcewinder filter). So, my AFRs are likely to be quite different than yours, unless your setup is VERY close to mine.

But, once I have the tune dialed in pretty close I plan to publish it here, complete, cell by cell.

Jim G
 

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Discussion Starter #4
Here's what the fuel map looks like today:



This has virtually completed eliminated the last of the shaking, except for tiny remnants that I cannot isolate fine enough with the available cells in the PC V fuel map. The bike now is glass smooth - images in the mirrors at the formerly troublesome rpm range are crisp and clear, and the bike accelerates with vigor from anywhere in that rpm range.

Jim G
 

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What about your gas mileage?
I've only yet done one partial fill. The trip meter said 98 miles, and my normal pump shutoff (I fill at only the same 2 stations, which one depending on where I went that day) occurred at 3.1 gallons. That means 98/3.1 = 31.6 mpg. But, really way too early to draw any conlusions.

BEFORE the handtuning, I typically got 33 to 39 in my "Hill Country" riding (no highway or freeway at all really), depending on mix of roads and speeds that tank, with many at 36 or so. BUT, the engine was unpleasant between 1800 and 2300 rpm. Now it's pleasant and strong.

It was Micah's dyno tune that showed me I was "missing out" by not getting a tune done before. After his tune, the low end grunt AND smoothness was phenomenal compared to before, but still felt unpleasant often in that 1800 to 2300 range, although mostly near 2000 to 2300 rpm, and around 15 to 20% throttle. His tune convinced me this engine had more to offer than we had yet been able to free up. I suspect Honda had a heck of a time tuning it for emissions, so it surged a lot, and the breathing improvements I had made, exhaust and intake working together, really highlighted that bad mixture.

Jim G
 

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I tried for months to get the low end torque to improve. I just kept adding fuel. it finally got so bad that I took it to a tuner. It took him 8 hours to get it straightened out. I still lug under 2500 rpms in 4th and 5th gears. I don't have an after market intake and have OEM modified pipes along with a PCIII (F) model. I am probably missing out on the low end performance by not adding air & fuel. I had a hyper charger on my 1300C and it did pretty well. I'm reluctant to add an open air box on this bike; I'd like to get 200,000 on it and I've read that the open K & N filters don't clean as well as they claim. I'm willing to sacrifice some performance for longevity. At 94 hp it's not exactly a moped.
 

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Discussion Starter #8
I was dissatisfied with the fuel mileage, and so am rerunning the iterative tuning sequence, starting again with Micah's dyno tune as delievred to me.

This time, I am noting, recording, and targeting only the specific combianitons of rpm and %throttle that exhibit any shaking, and NOT trying to "smooth" out the transitions to other points aroudn them. That is proving to be vERY effective, despite its flying in the face of normal tuning smoothing techniques.

I have found that the only points where the shaking actually occurs with his tune are focused within no lower than 1750 and no higher than 2500 max, and only within the 20% to 30% throttle range. I am attacking those specific ranges ONLY, and am trying both richening and leaning this time, since Micah had richened them quite a bit in response to the 4-gas readings he was getting. It actually looks to me like both richening and leaning reduce the shaking, BUT the leaning is intuitively the direction to go, since Micah richened those secific points quite a bit more than other points, so I am moving in the lean direction. So far, I have had good success, but not quite there yet. But, today's fuel fillip showed about 35 mpg, which is better than I would expect under the hilly, winding rtoads conditions I am testing under.

Interestingly, this range of rpm and %throttle is kind of key to a cruiser, as I find, with my "throttle % gage" (see photo above) that I spend the vast majority of my time when actually cruising at steady speeds, at 2500 rpm and 20% to 25% throttle.

Jim G
 

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I was dissatisfied with the fuel mileage, and so am rerunning the iterative tuning sequence, starting again with Micah's dyno tune as delievred to me.

This time, I am noting, recording, and targeting only the specific combianitons of rpm and %throttle that exhibit any shaking, and NOT trying to "smooth" out the transitions to other points aroudn them. That is proving to be vERY effective, despite its flying in the face of normal tuning smoothing techniques.

I have found that the only points where the shaking actually occurs with his tune are focused within no lower than 1750 and no higher than 2500 max, and only within the 20% to 30% throttle range. I am attacking those specific ranges ONLY, and am trying both richening and leaning this time, since Micah had richened them quite a bit in response to the 4-gas readings he was getting. It actually looks to me like both richening and leaning reduce the shaking, BUT the leaning is intuitively the direction to go, since Micah richened those secific points quite a bit more than other points, so I am moving in the lean direction. So far, I have had good success, but not quite there yet. But, today's fuel fillip showed about 35 mpg, which is better than I would expect under the hilly, winding rtoads conditions I am testing under.

Interestingly, this range of rpm and %throttle is kind of key to a cruiser, as I find, with my "throttle % gage" (see photo above) that I spend the vast majority of my time when actually cruising at steady speeds, at 2500 rpm and 20% to 25% throttle.

Jim G
Jim, I thought that the aim of your experiment was to get rid of the shaking and I understand that you managed to do that which is a very good point!. However it is no surprise that richening the A/F mixture has caused a drop in mileage which you have to accept.
 

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Jim, I thought that the aim of your experiment was to get rid of the shaking and I understand that you managed to do that which is a very good point!. However it is no surprise that richening the A/F mixture has caused a drop in mileage which you have to accept.
It would "seem" logical that richening the mixture on an engine would reduce fuel mileage, but that is NOT a given. The reason is that if a mixture is too lean to begin with, it makes the engine very inefficient in its efforts to propel the vehicle. Richening the mixture can actually improve the mileage while also making the engine far more pleasant.

A stunningly good example is most of the cars built in the time period of about 1974 through 1985. They were VERY lean in an effort to reduce emissions, and had horrible feel and performance. A 1976 Corvette, like I actually owned back then, developed PEAK horsepower of only about 180 GROSS hp at the crank, and that was the "hi-performance" L-82 version! Gas mileage too was stunningly bad comapred to today's 450 hp 2014 Corvette (EPA Hwy rating of 29) and even compared to my current stock 300 REAL crank hp 1992 Corvette (EPA hwy rating of 24 mpg).

Do not assume that my experimentation will end with low fuel mileage. Eliminating the shaking also eliminates a performance problem.

Jim G
 

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What's new Jim?

It would "seem" logical that richening the mixture on an engine would reduce fuel mileage, but that is NOT a given. The reason is that if a mixture is too lean to begin with, it makes the engine very inefficient in its efforts to propel the vehicle. Richening the mixture can actually improve the mileage while also making the engine far more pleasant.

A stunningly good example is most of the cars built in the time period of about 1974 through 1985. They were VERY lean in an effort to reduce emissions, and had horrible feel and performance. A 1976 Corvette, like I actually owned back then, developed PEAK horsepower of only about 180 GROSS hp at the crank, and that was the "hi-performance" L-82 version! Gas mileage too was stunningly bad comapred to today's 450 hp 2014 Corvette (EPA Hwy rating of 29) and even compared to my current stock 300 REAL crank hp 1992 Corvette (EPA hwy rating of 24 mpg).

Do not assume that my experimentation will end with low fuel mileage. Eliminating the shaking also eliminates a performance problem.

Jim G
I have been absent for a while. Curious if you found a tune that works for you. My bike still seems to struggle in the discussed ranges. Run extremely well if you are above 3,000 in 5th. Lower than that I get the chug-a-lug shake in 5th.
 

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Here's what the fuel map looks like today:



This has virtually completed eliminated the last of the shaking, except for tiny remnants that I cannot isolate fine enough with the available cells in the PC V fuel map. The bike now is glass smooth - images in the mirrors at the formerly troublesome rpm range are crisp and clear, and the bike accelerates with vigor from anywhere in that rpm range.

Jim G

Jim I would like to give your map a try. I have a PC III and would most likely have to enter the cells manually. However if I enlarge this image its not viewable. any chance of getting a better image pm to me. let me know.

Tony
 

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Jim I would like to give your map a try.Tony
You are in the tricky zone of 4400 ft above sea level.

ProStock drag racing at Mile High - 5000 ft was killing it bad, unless turbo or supercharged.
Lot of blown engines that week.

Regardless what map is used - I'd want to see fuel ratio live next to speedo/tach.
 

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Discussion Starter #14
To those still quoting my posts and asking me questions: Hey guys, I sold my VTX back in early February and then at end of February bought a brand new 2014 Harley Breakout.

My efforts on the tuning made my VTX notably better in the under 2200 rpm range, but I never could get it perfect despite lots of trying. I concluded that despite the VTX's other very attractive characteristics, that "shaking" was never going to be entirely eliminated, and I happen to be VERY sensitive to it. I sold it because I am that sensitive to that shaking, despite the fact I had spent a lot of time, effort, and money getting that bike otherwise "perfect" for me.

My friend Micah Shoemaker, who is a world class engine builder and tuner, told me that he thinks the VTX has an intake reversion problem or other non-tunable issue. He and I both watched the rear fender and battery while he tuned, because both vibrated incredibly in the problem rpm range.

Micah says some engines just do things like that, and some people are very sensitive to it. He himself has a consistent problem tuning Suzuki Hayabusas - they make him physically sick, and he has to take breaks when tuning them. Some of the really high rpm 600s do the same thing to him.

My Harley Breakout has no such issue fortunately. Even with the Harley Stage 4 Race kit I had the dealer install, which includes a cam set that peaks the power at 6200 rpm, I can run all day at 2000 in 6th gear (55 mph).

Another shocking difference is the fuel mileage. My VTX mostly got fuel mileage in the mid to high 30s, even when ridden pretty conservatively. The Harley gives me a consistent and reliable 42 to 45.5 mpg even with the Stage 4 Race kit. Yes, my Breakout weighs only 700 lb wet, but my mods had gotten my VTX down to 770. This seems to support the idea that there is something inherently amiss with the VTX.

I do miss the VTX. Its low rpm torque around town was incredible - better than my Harley with or without the Stage 4 kit, and the numerically high gearing on the VTX, especially in 1st gear, made the bike seem like a real hotrod. And, it could turn notably easier than my Breakout with its 240 mm rear tire. But there was no way I could picture traveling long distance on the VTX because of the residual shaking I still felt in that rpm range.

Jim G
 
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