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Discussion Starter · #1 ·
I know it has been a long time coming but we are in the R&D phase with our Grom. We are using the Air Fuel Ratio to get a better understanding of how the Grom is actually running. Here at Dobeck Performance, we strive to keep the general public informed and educated. So, if you dont know what an AFR is, or how you can use it for tuning, check out this video.

I am also posting two videos of the Grom running on our scooter dyno, with the SAFR diagnostic tool giving AFR readings. This is at about 34 degrees outside and at 4,459 ft above sea level. I will post more information as we get it. Its been really busy here, but the Grom is finally on the dyno.
 

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Bravo! Hopefully, this will give some aspiring shadetree tuners some concept of what they don't yet understand...critical knowledge, essential for any chance at successfully remapping an ecu to match a non-stock tune.

Without realtime A:F numbers, fuel curve tuning is blind guesswork. Even with a nice gauge, like this, it's still quite a challenge to monitor with a bike...could be dangerous anyplace other than a dyno, where one doesn't also have to monitor traffic and keep the shiny side up. Then there's technical side, understanding how to interpret data and edit the various maps, even with a first-class data logger in place of a chassis dyno.

Aside from that brief bit of transient weirdness around the 3:00 point in the first video, looks to me like the factory really spent some time to dial-in the stock mapping. Considering that this is a fairly simple speed-density system, I'm well impressed that the mixture heads into the low-mid 12s under full power/WOT...as well as how clean the startup & decel values are. I am assuming that the cold 34F ambient air temp goes some way toward compensating for the 4500ft altitude.
 

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First video is nice info for beginners, but very basic. Another good source if you want to get a more in depth is the megasquirt website. There is a lot of valuable information on there and there are very knowledgable people on the forums. It provides formulas for different fuel types and about as much info as you will need to make a fuel map from scratch. It just depends on how far you are willing to go. I fitted the Akunar piggyback system, which made a noticeable difference after my engine mods. Unfortunately I don't have a dyno at the moment at my disposal, but i did get it pulling much better with more mid and top end than without it. Problem is the check engine light stays on. It will work as a low cost option until this system or the PCV is ready. I also verified yesterday myself that the 33 pin ECU connector is a direct fit with the cbr125 connector. I am currently working to fit the cbr125 throttle body on the MSX, but am waiting on the yuminashi cam which may be here next week. I have the yoshimura full system, 150cc light bore kit and light bore injector installed.
 

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First video is nice info for beginners, but very basic. Another good source if you want to get a more in depth is the megasquirt website. There is a lot of valuable information on there and there are very knowledgable people on the forums. It provides formulas for different fuel types and about as much info as you will need to make a fuel map from scratch. It just depends on how far you are willing to go. I fitted the Akunar piggyback system, which made a noticeable difference after my engine mods. Unfortunately I don't have a dyno at the moment at my disposal, but i did get it pulling much better with more mid and top end than without it. Problem is the check engine light stays on. It will work as a low cost option until this system or the PCV is ready. I also verified yesterday myself that the 33 pin ECU connector is a direct fit with the cbr125 connector. I am currently working to fit the cbr125 throttle body on the MSX, but am waiting on the yuminashi cam which may be here next week. I have the yoshimura full system, 150cc light bore kit and light bore injector installed.

Snake

Can you give us the settings you are running on the Fuel Controller

I have one on order to and have exactly the same mods as you on my daughters bike.

Also - has anyone else had the Warning light stay on with this controller - there are a few who have fitted it.

Did you get your smoking rings sorted? - Was there a broken ring?
 

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I'm still tinkering with the settings so I don't have anything permanent yet. Once I find something that works well I'll post it up. Yesterday when the engine was warm I had some pretty good results In the mid and top end. I just need to figure out the ignition settings that work best. The Idle - 25% range needs a bit of adjustment still. Keep in mind I've only been playing around with it for about an hour because the weather is crap today.
 

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Discussion Starter · #8 ·
The fueling on this little/big, bike is pretty good. Honda obviously put some time into the fueling. We are still messing around with the elevation settings right now, so everything is still stock. After we get done with that, we are going to figure out exactly what needs to be done with the O2 sensor. Then its time to start modding. If you are looking for any particular information, let me know.
 

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First video is nice info for beginners, but very basic. Another good source if you want to get a more in depth is the megasquirt website. There is a lot of valuable information on there and there are very knowledgable people on the forums. It provides formulas for different fuel types and about as much info as you will need to make a fuel map from scratch. It just depends on how far you are willing to go. I fitted the Akunar piggyback system, which made a noticeable difference after my engine mods. Unfortunately I don't have a dyno at the moment at my disposal, but i did get it pulling much better with more mid and top end than without it. Problem is the check engine light stays on. It will work as a low cost option until this system or the PCV is ready. I also verified yesterday myself that the 33 pin ECU connector is a direct fit with the cbr125 connector. I am currently working to fit the cbr125 throttle body on the MSX, but am waiting on the yuminashi cam which may be here next week. I have the yoshimura full system, 150cc light bore kit and light bore injector installed.
The first video is a good baseline, for more than just beginners. It answered the all-important "how thoroughly did the OEM map the stock system?" Without knowing that, it's all trial & error...looking for performance left on the proverbial table. The real-world results show that would be a fruitless pursuit, on an otherwise stock tune.

That said, once you start making hardware changes, then it's time to tweak ECU maps. Learning how to create a base fuel map from scratch is interesting reading but little more than theory that maybe helps further understanding of how EFI works. There's a lot more to consider than just base fuel. Mapping an ECU, completely from scratch, for a new application, takes some serious wherewithal...even for an OEM; imo, it's completely beyond virtually all riders, at this early date. It's also largely irrelevant, where piggyback devices are involved; that's the whole idea...use the high-res, OEM, mapping and tweak it to suit the new tune.

You've got an interesting project going. IMO, sounds like you're heading in the right direction. I'm sure I'm not the only one here who'd like to see you succeed, which brings this post full circle. The first hurdle is getting beyond a carb-tuning mindset. Without a reliable A:F meter, it's guesswork at best. Not knowing what's triggering the MIL would bother me, in a big way. It could be trying to tell you that something is far outside of acceptable parameters. Due to the nature of digital FI, a relatively small, hard-to-detect, mapping error could be costing you output, fuel mileage or even lead to engine damage. Seat-of-the-pants simply won't cut it with EFI tuning, beyond verifying what the gauges indicate, unless you're extremely lucky.
 

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The first video is a good baseline, for more than just beginners. It answered the all-important "how thoroughly did the OEM map the stock system?" Without knowing that, it's all trial & error...looking for performance left on the proverbial table. The real-world results show that would be a fruitless pursuit, on an otherwise stock tune.

YThat said, once you start making hardware changes, then it's time to tweak ECU maps. Learning how to create a base fuel map from scratch is interesting reading but little more than theory that maybe helps further understanding of how EFI works. There's a lot more to consider than just base fuel. Mapping an ECU, completely from scratch, for a new application, takes some serious wherewithal...even for an OEM; imo, it's completely beyond virtually all riders, at this early date. It's also largely irrelevant, where piggyback devices are involved; that's the whole idea...use the high-res, OEM, mapping and tweak it to suit the new tune.

You've got an interesting project going. IMO, sounds like you're heading in the right direction. I'm sure I'm not the only one here who'd like to see you succeed, which brings this post full circle. The first hurdle is getting beyond a carb-tuning mindset. Without a reliable A:F meter, it's guesswork at best. Not knowing what's triggering the MIL would bother me, in a big way. It could be trying to tell you that something is far outside of acceptable parameters. Due to the nature of digital FI, a relatively small, hard-to-detect, mapping error could be costing you output, fuel mileage or even lead to engine damage. Seat-of-the-pants simply won't cut it with EFI tuning, beyond verifying what the gauges indicate, unless you're extremely lucky.
My AF meter will be here soon and Ill be able to see how its running. I do have the engine idling and it revs pretty well now with the CBR throttle body. I haven't taken it out on the road and put the engine under load yet for the reasons you mentioned. From what I learned back in college and the many sources available on engine tuning etc... there isn't much you cant learn on how to tune except what experience and trial and error teaches you. Many people would have you believe its beyond most people and i have to disagree. EFI tuning Is like anything else and can be learned. I saw Yuminashi is charging $400+ for their 31mm throttle body and i thought it could be done much cheaper with existing used parts. Since the cbr 125 has the exact same 33 pin ecu plug I was hoping the system would be similar. Every plug on the TB is different, but It may still work. On a stock 125 engine it may not make much of a difference, but with big bore kits it may help. At any rate its a fun project and if it doesn't work with the piggy back controller ill just put the stock TB back on until the auto tune comes out from PC. I talked to one of their engineers a few weeks ago and they are working on a system.


Sent from my iPad using HondaGrom.net
 

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My AF meter will be here soon and Ill be able to see how its running. I do have the engine idling and it revs pretty well now with the CBR throttle body. I haven't taken it out on the road and put the engine under load yet for the reasons you mentioned. From what I learned back in college and the many sources available on engine tuning etc... there isn't much you cant learn on how to tune except what experience and trial and error teaches you. Many people would have you believe its beyond most people and i have to disagree. EFI tuning Is like anything else and can be learned. I saw Yuminashi is charging $400+ for their 31mm throttle body and i thought it could be done much cheaper with existing used parts. Since the cbr 125 has the exact same 33 pin ecu plug I was hoping the system would be similar. Every plug on the TB is different, but It may still work. On a stock 125 engine it may not make much of a difference, but with big bore kits it may help. At any rate its a fun project and if it doesn't work with the piggy back controller ill just put the stock TB back on until the auto tune comes out from PC. I talked to one of their engineers a few weeks ago and they are working on a system.


Sent from my iPad using HondaGrom.net
I like pc autotune because the trim corrections for wot can be set to your liking and it can be tuned to only correct a small amount rather then a few afr points. Tune in open loop first then setup your correction tables and reap the benefits.

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thats a cool video but ide like to see it with load so take it out and ride and get the video
 

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What do ya'll think.

if the only mods i do to my grom is a KN intake and full yoshi, will i need a PC/Juicebox?

Since both are going to be in the $250-$400 range, would it be more for the riders that will be doing more engine mods ie. throttle body or LBK/BBK?
 

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What do ya'll think.

if the only mods i do to my grom is a KN intake and full yoshi, will i need a PC/Juicebox?

Since both are going to be in the $250-$400 range, would it be more for the riders that will be doing more engine mods ie. throttle body or LBK/BBK?
You shouldn't need to with the stock bore. I would imagine the ECU can adjust the fuel trim for just an intake and exhaust. That being said its possible with a way to adjust the fueling you could squeeze a little more power out if Honda tuned it for economy.

What id really like to see is a dyno run with the stock against just the K&N and then with the yosh exhaust alone then another with the K&N and yosh installed together.


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You shouldn't need to with the stock bore. I would imagine the ECU can adjust the fuel trim for just an intake and exhaust. That being said its possible with a way to adjust the fueling you could squeeze a little more power out if Honda tuned it for economy.

What id really like to see is a dyno run with the stock against just the K&N and then with the yosh exhaust alone then another with the K&N and yosh installed together.


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IThat would be nice. so that we could see exactly what each mod does!!!
 

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My AF meter will be here soon and Ill be able to see how its running. I do have the engine idling and it revs pretty well now with the CBR throttle body. I haven't taken it out on the road and put the engine under load yet for the reasons you mentioned. From what I learned back in college and the many sources available on engine tuning etc... there isn't much you cant learn on how to tune except what experience and trial and error teaches you. Many people would have you believe its beyond most people and i have to disagree. EFI tuning Is like anything else and can be learned. I saw Yuminashi is charging $400+ for their 31mm throttle body and i thought it could be done much cheaper with existing used parts. Since the cbr 125 has the exact same 33 pin ecu plug I was hoping the system would be similar. Every plug on the TB is different, but It may still work. On a stock 125 engine it may not make much of a difference, but with big bore kits it may help. At any rate its a fun project and if it doesn't work with the piggy back controller ill just put the stock TB back on until the auto tune comes out from PC. I talked to one of their engineers a few weeks ago and they are working on a system.


Sent from my iPad using HondaGrom.net
Any technology can be learned, the question, in this case, is "by how many, in the real world?" I've been in the tuning game since the Z50 & CT70 were new new models. The number of people I've run across who really know what they're doing with carburetors has been shockingly, small. Make a big mistake with a carb and the most likely outcome is an engine that won't rev out, it either floods out or won't take throttle...change a jet, jet needle height, float level - or if one is a real expert, slide cutaway or airbleed orifice size. There aren't very many carburetor choices, for small engines. Thus, that world consists of a relatively small number of known combinations. And, carbs are largely self-adjusting, since fuel delivery depends on airflow volume of the engine. Not so with EFI, you'd better known what you're doing. A seemingly minor oversight can make paperweights. I jumped into custom EFI about 20 years ago, on the automotive side. Started out by hiring "expert" help to get a one-off setup dialed-in...by one of the premier outfits in North America. Even they didn't get it quite right...unless you consider a 70rwhp & 5mpg loss "getting it right". Took me a month to get the thing sorted...and that was equipped with a laptop on the passenger seat. Getting all of the various temp-related map values dialed-in took another 18 months. Without a temperature-controlled chamber to simulate summer vs winter ambient temps, had to wait for the real thing.

I suspect the odds are good that you will get this sorted and you won't be the only one. No insult intended but, I also believe that you're grossly overestimating the tuning skills of most people. Otherwise, I wouldn't be reading numerous posts about "light bore injector" swaps, eliminating the airbox & charcoal canister and the like, hoping for big gains from stock motors. I don't see EFI tuning becoming a viable DIY proposition, for the vast majority, until the aftermarket first steps in to do the heavy lifting...offering full-time closed-loop operation and self-mapping systems and at a price level that most will accept, while still allowing a viable profit magin (not many outfits can work for free, or at a loss). Another longshot in the "everyday waldomart low price" era.

On the automotive side, most "DIY tuners", throw money at cat-back exhausts, cold air intake assemblies and silly gauges. Notice any similarity? The majority of "hardcore tuners" purchase pre-engineered & tested packages, that include ECU remapping...or farming-out the job to a tuning shop. The DIY component involves re-mapping an ECU using a pen & checkbook.
 

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Any technology can be learned, the question, in this case, is "by how many, in the real world?" I've been in the tuning game since the Z50 & CT70 were new new models. The number of people I've run across who really know what they're doing with carburetors has been shockingly, small. Make a big mistake with a carb and the most likely outcome is an engine that won't rev out, it either floods out or won't take throttle...change a jet, jet needle height, float level - or if one is a real expert, slide cutaway or airbleed orifice size. There aren't very many carburetor choices, for small engines. Thus, that world consists of a relatively small number of known combinations. And, carbs are largely self-adjusting, since fuel delivery depends on airflow volume of the engine. Not so with EFI, you'd better known what you're doing. A seemingly minor oversight can make paperweights. I jumped into custom EFI about 20 years ago, on the automotive side. Started out by hiring "expert" help to get a one-off setup dialed-in...by one of the premier outfits in North America. Even they didn't get it quite right...unless you consider a 70rwhp & 5mpg loss "getting it right". Took me a month to get the thing sorted...and that was equipped with a laptop on the passenger seat. Getting all of the various temp-related map values dialed-in took another 18 months. Without a temperature-controlled chamber to simulate summer vs winter ambient temps, had to wait for the real thing.

I suspect the odds are good that you will get this sorted and you won't be the only one. No insult intended but, I also believe that you're grossly overestimating the tuning skills of most people. Otherwise, I wouldn't be reading numerous posts about "light bore injector" swaps, eliminating the airbox & charcoal canister and the like, hoping for big gains from stock motors. I don't see EFI tuning becoming a viable DIY proposition, for the vast majority, until the aftermarket first steps in to do the heavy lifting...offering full-time closed-loop operation and self-mapping systems and at a price level that most will accept, while still allowing a viable profit magin (not many outfits can work for free, or at a loss). Another longshot in the "everyday waldomart low price" era.

On the automotive side, most "DIY tuners", throw money at cat-back exhausts, cold air intake assemblies and silly gauges. Notice any similarity? The majority of "hardcore tuners" purchase pre-engineered & tested packages, that include ECU remapping...or farming-out the job to a tuning shop. The DIY component involves re-mapping an ECU using a pen & checkbook.
I completely agree with you, automotive engines are much more complex than this single channel system and the grom wont be even close to as difficult to tune as say an LS3 for example. I see a lot of young guys throwing money away on mods on cheap Japanese cars that in my opinion are not worth the effort to tune, but I guess some would say the same about the grom too. Most will want proven plug and play systems which is understandable. I love the challenge to see if I can get more out of this engine with parts that are not made for it.

It's possible putting on a full exhaust, big bore kit and K&N has reduced performance in some parts of the rev range, I even think its likely, but until I get it on a dyno and try different combinations I won't know. I'm not going to buy a $50K+ dyno just to satisfy my curiosity though. I'm also not just going to take a guys word for it that his bolt on products from Thailand will give me instant performance gains until I see it for myself. Hogging out the intake and exhaust ports is also a misconception I think many people have and most likely reduce performance. Tuning is an art form, but i find it fascinating.

Will you be tuning your grom as well or leaving it stock?


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Guys. When a viable tuning solution comes out (power commander) I fully intend to offer my services for custom and ots calibrations for a range of modifications with dyno results and data to back it up. I have done oem calibration work for some of the bikes\trikes on the road today as well as performance tuning up to 500hp per liter of displacement. I have kept my bike stock for this reason and I will be using an epa certified mustang advanced engineering ac motoring motorcycle dynamometer. The same one I have used for epa emissions certifications. There should be some nice gains to be had with this bike and 93oct.

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