Wide Band (WBO2) and Narrow Band (NBO2) O2 Sensors

[Rednaxs60]

My '85 1200 GW FI ECU replacement/upgrade/modernization project required I install a WBO2 sensor for engine tuning and normal operation. The original system did not have one. I mentioned in one of my posts that an O2 sensor would be good to install to tune carbs. Knowing the AFR for idle and general engine performance through the engine RPM up to WOT may provide good information as to how to "jet" the carbs for your riding profile and area. You would need to use a WBO2 sensor, and not a NBO2 sensor. A NBO2 sensor only indicates a lean/rich AFR condition. A WBO2 sensor provides AFR readings for various engine load conditions.

For idle jets, you would want to achieve an AFR reading close to 14.7 AFR. If you have several sizes available to experiment with you can change the jetting to determine what the engine likes. The same with the main jets and jet needle.

Installation of an O2 sensor could assist in determining if the carbs need to be tuned after an exhaust system change as this is a popular upgrade/change.

Not for everyone, just thinking out loud. Thoughts?

Cheers

[Shadowjack]

I had an AEM aftermarket sensor going unused when I was kludging up my 1200-into-1000 engine swap. I had to make adapter pipes to get the aftermarket Yoshimura mufflers to fit anyway, so I put a bung in each side. I used it for a while, but eventually removed it, because there was nothing to keep the weather out. It did tell me that for some reason the stock pilot jets were too small (way out there at 14-17 AFR and bone-white plugs), but the only size I could find that were bigger were slightly too large--seems like you can only get selected sizes any more. So now it pops right off when cold, but has to crank a bit when hot.

[Rednaxs60]

Thanks for the reply. Forum has been quiet so I thought I'd post some of my thought to engender some discussion.

Good to read that you tried an O2 sensor. I'm not advocating keeping an O2 sensor installed, but to use it when troubleshooting or making changes to the original system.

My project, '85 1200 GW FI model ECU replacement (has turned into a modernization project), required I install an O2 sensor. It has been mentioned on the Speeduino forum, I'm using a Speeduino clone ECU, that Honda was/is the "King" of the lean burn. I tend to agree with this as my GW typically got 45 to 50 IMPG when cruising. One of the inmates on the Speeduino forum indicated that he has seen AFR readings for a Honda in the 17 AFR range. I would submit that Mr Honda designed the Honda GW engine much like an auto engine, probably why there are so many engine parameters that you cannot change or change very little such as engine ignition timing.

You mention that the AFR readings were more lean than you would expect or want, and larger jets would be advantageous to install but not available. A possible solution is to install an aftermarket ECU such as a Speeduino ECU for ignition only. A project needing some component additions and such, but you would be able to alter the engine timing to achieve AFR readings that you want. Advanced engine timing leans out the air-fuel mixture, retarded engine timing richness the air-fuel mixture. Can't do this with the OEM ignition control module, timing is fixed.

It was posted on my Speeduino forum thread that engine timing by an OEM is a compromise that is good for normal street operation. A tuneable ignition table can result in much better engine operation and performance. Theory has it that the fuel into a cylinder should be completely combusted to coincide with the engine piston being between 10 and 20 degrees ATDC for optimum power and fuel economy. Lots of info on-line regarding this and what happens.

Spark plug reading is an interesting topic. A bone white plug is from a well tuned engine, lean burning engine. Most OEMs are doing this and we don't realize it, ignorance is bliss so to speak. The plugs from my 2008 Ford Escape have a porcelain tip that is bone white. This is a web site that is a good read regarding spark plugs: https://honda-tech.com/forums/forced-in ... A-3063102/

Thanks for the reply.

Cheers

[dontwantapickle]

... but you would be able to alter the engine timing to achieve AFR readings that you want. Advanced engine timing leans out the air-fuel mixture, retarded engine timing richness the air-fuel mixture.

They say that just opening or closing the plug gap can affect the wideband numbers.
Makes sense because plug gap does affect timing.

[Rednaxs60]

I suspect that the wider the spark plug gap the weaker the spark, the smaller the spark plug gap the stronger the spark. The spark duration is the same. I have read the same. Spark plug gap orientation is also a topic for discussion. Both issues require experimentation to get the best result(s), need higher priced help and equipment.

I submit that spark plug gap affects the air-fuel ratio and not the ignition timing. The better the fuel burn within the ignition timing and coil discharge profile, the better the AFR numbers depending on what the engine tune is for.

Ignition timing is fixed, for example a carbureted engine; for a specific engine load and RPM, the ignition timing is to start at 25 degrees BTDC - once set, done deal. The spark duration is specific to the amount of time required to discharge the coil charge through the spark plug. I submit that the spark plug gap is directly related to coil discharge and not engine ignition timing, and is related to best fuel burn.

As you mention, and as mentioned above, spark plug gap can affect AFR readings (fuel burn), not engine ignition timing.

Just MHO. Cheers

[Shadowjack]

As I recall from my intensive study (at the time) of Hot Rod and other fine publications of that type, the emissions standards in the early 70s required leaner mixtures than previously. Leaner mixtures wouldn't ignite as well unless the gap was opened so more molecules would get between them. Points-style ignitions didn't have the oomph to fire across such wide gaps, leading to the amplified electronic ignitions used since. I believe that some manufacturers tried gaps up into the fifty and sixty thousandths, then closed them up again in later models. The fact that everyone was chasing better fuel mileage enters into it, but really just confuses the issue as far as the mechanics and chemistry involved.

[redglbx]

Red, this is an interesting conversation. I have spent time on my buddies dyno with my 76 wing and my 80 CBX that was equipped with a lambda sensor (02 sensor) and I’m lucky to have an old Sun machine that also has an A/F meter on it so I got to compare between my Sun Machine and the Dyno sensor readings a lot.

As stated above and I have seen Honda A/F ratios are very much the same across their product lines , typically very lean on the idle circuit being in the 15-17/1 a/f ratio. Adding in the intermediate midrange jetting improves things a bit but is still very lean and then adding the main fuel jetting it typically goes “pig” rich in the 10.5-12.0 to one a/f ratio, just pig rich.

So I’ve been changing the jetting on the carbs for a long time, you’re correct in that there is very limited jetting availability, I typically get mine from Jets-r-us or PJ’s Motorsports and normally I jet 1000 carbs the same.

Idle jets at the stock 35, yes very lean but it doesn’t foul spark plugs.

Intermediate (primary main), stock is usually a #62 jet and usually change to a #65

Main (secondary mains) stock is usually a #120 which is just pig rich, I usually put a #115 here to lean things down some.

Lastly I change the idle air jet in the brass tubes which are 115’s oe and I change these to a #110 jet.

All of this gives a much more linear fuel a/f ratio usually around 12.8 to 13.2 to one a/f ratio, much flatter fuel curve and leaning the top out a bit produces a couple of more h-power as well, I wouldn’t lean it out anymore though.


Ignition, I have studied and followed the teachings of a guy named Chris Jacobs (Jacobs Electronic Ignitions) and have learned a lot from him.

He is a big proponent of opening the spark plug gaps a lot as he claims the getting the flame kernel out to .080in is a big deal because once it’s at .080in then combustion occurs nearly instantly from that point requiring less initial timing. The problem is that you must have the ignition components to support a wider gap. He prefers a .060-.080in of a gap. Changing the plug gap definitely affects the initial timing which must be corrected if you change the gap. More plug gap will retard the initial timing and of course closing the gap advances the initial timing.

The downside to opening the plug gap is that wider gaps make the engine more sensitive to spark knock & preignition. Everything affects everything. I need more coffee !

[Rednaxs60]

Thanks for the reply. Forums are a bit slow so I thought I'd post something that might get some traction. These forums are great but need a poke every now and then.

A lot of my thoughts are based on the '85 1200 GW CFI system upgrade/modernization project I'm progressing with. Honda did a great job with the GW engine design, but then we got our hands on the bike(s) and all bets are off. Want to keep my '85 operating and performing well for a while.

From an engine tuning perspective, since we (the global we) change parts/components due to obsolescence, or to do an upgrade, I'm of the opinion that these engines are very resilient. We change exhaust systems, different coils, carbs, and based primarily on seat-of-the-pants tuning. It just works and generally works well.

Nice to read about an owner testing and getting some empirical data to use. A lot of us probably learned about these issue(s) many years ago, but filed them away because we never had to use these. The new ECU I'm using, and the engine tuning and data analysis software makes a person dust off the cobwebs very fast. There's a lot to engine tuning, carb or FI.

Thinking about the above and what I have been going through with my project, I think that discussing issue(s) such as this is good for the community at large.

Getting back to the thread topic, have read up on "reading spark plugs". Interesting topic and one that dove tails nicely with this topic. These two web sites, of which there are many, are a good read and viewing: https://www.youtube.com/watch?v=yvTeyNM_BwY&t=991s and https://honda-tech.com/forums/forced-in ... A-3063102/. Have to destroy a couple of plugs in the process.

Thanks again for the reply/comment.

Cheers

[dontwantapickle]

Tuning an engine is a whole different game from back I first started wrenching.

Adjusting points with a matchbook...
Turning the distributor till the engine pings and backing it off a bit...
Opening or closing valve clearances...
etc...

Reading plugs was really the only indicator we had to determine if our changes were going in the right direction.

Today, A digital tach and an AEM wideband are my only "high tech tools".
When it comes to ignition timing, I still static time as a baseline and end up tuning my engines by ear.


Modern engines... add a ECM, a bunch of sensors and a laptop and a person can make an engine run optimally without ever picking up a screwdriver.
Probably a easier and more precise way of tuning, but it's all just a little past me and my old fashioned methods.

[Rednaxs60]

I hear you regarding this. Be hard pressed today to find a matchbook

My father was truly gifted at this, a "hair" here and there. The issue is to give oneself the best chance for success regardless of the fuel/ignition setup. Not a lot can be done with the GW engine timing, Honda provided just enough information to have the shop or the DIY mechanic ensure the engine would operate as designed. The 1200 carb GW timing is cast in concrete, cannot be changed/adjusted. 1200 GWs are good candidates for an aftermarket ECU ignition only upgrade.

Cheers

[wingrider]

I bought a wideband one for when I finally get to my 77 project…figured it can’t hurt to see how the EFI is acting on that one.

[Rednaxs60]

A WBO2 sensor is a good tuning tool, and relates 100% to fuel.

For my project, the first engine tuning issue with the new ECU is fuel, getting it under "control" so that you aren't fouling plugs or smoking yourself out of the garage. The VE (fuel) table is the most important followed by the spark (ignition timing) table, then the AFR table.

The AFR table is used to fine tune the engine tune in that the ECU uses this table in conjunction with the O2 sensor to bring the engine back to the RPM/load that the engine is being operated at. After the VE and spark tales are calibrated, the other features functions such as using the O2 sensor, dealing in the coils/injectors, acceleration enrichment, fuel injector close angles and many others are enabled/turned on (one at a time).

The OEM ignition timing profile will probably be the best you can do because timing for most early GW engines is an alignment timing mark (crank to camshaft) and an idle mark. No other timing marks available. With eh 1200 carb models, the ICU controls engine timing and cannot be adjusted/changed.

I have started a thread on the Classic GW forum regarding an EFI ignition only install. The 1200 GW ICU can't last forever.

Cheers.

[redglbx]

One more input from my old age stuff,

Spark plugs, to properly tune your engine using the spark plugs requires that you install new plugs and then with minimal running so as not to soot the plugs up, make a pass at max throttle shutting the ignition off at the end immediately. Pull the plugs and look at the ceramic, properly jetted/tuned should give you a carbon ring on the ceramic at about the end of the threads, coloring is secondary on this.

Any additional running will alter the results, some which is why an A/F lambda sensor is a good alternative.

On another note, I had a 86 SEi which was a good bike that I kinda wish I hadn’t sold, it ran exceptionally well once I went back through and corrected things that the OE owner had neglected from new. I sold it because a lot of my “knowledgeable” friends convinced me that the fuel injection was a large liability due to no replacement parts. Your work on your 85 LTD is encouraging but again makes me wish I had kept my 86. Thanks for sharing your info.

[Rednaxs60]

I would suspect that two O2 sensors, one for each cylinder bank may be required for engine tuning. The '85/'86 FI models are not able to do a cylinder to cylinder balance, but is able to have the right/left cylinder banks balanced. This ensures that each cylinder bank is doing the same work during engine operation. O2 sensors would be beneficial for tuning the engines of these bikes as well.

Theoretically, FI system fuel injectors should be better calibrated and as such, each injector should flow approximately the same amount of fuel. Reality is that this is not the case. No two fuel injectors are the same. That is why engine tuning software has individual cylinder fuel trim (ICFT). This ICFT tuning has a small user defined fuel table for each injector to balance the fuel being delivered to each cylinder to ensure best engine performance and operation. This feature is only available for sequential fuel injection.

You could also pay a premium for a "balanced" set of injectors. The issue with this is you do not know exactly how the balancing was done, what fluid was used, temperature. The balancing pressure is generally at 43 PSI (3 bar), but what happens when your FI system is designed to operate at a design pressure of 28 to 32 PSI as the '85/'86.

I have mentioned that fuel delivery to the engine is the priority. A generic ignition timing table can be used and the engine will operate. It's all about fuel, everything else follows.

Read a lot of posts about the '85/'86 GW FI models, and how the FI system is a liability. All motorcycle systems are a liability after a long time and I would submit that the newer motorcycle systems will not escape this reality.

Reading a lot of forum posts regarding issues with early year carbureted GWs and how these are now being just as much a liability, parts obsolescence.

I bought my '85 GW FI model because I wanted a GW FI early model, thought it might be less expensive than a newer one (not), and needed a retirement project. I've enjoyed working on mine for the last 9 years and expect I will continue modernizing it for a few more. Your ex-'86 FI model had all the necessary FI components for a new ECU install with a few exceptions.

I've had to learn a good wiring/PCB software - schematics of changes is very important, KiCad, and a lot about EFI and the various components.

I know about the spark plug reading process, but lacking other good engine tuning tools, it is still a good indication - better than none at all. You are correct, an O2 sensor is much better.

I mentioned that I started a thread over on the Classic GW forum regarding a replacement ICU project. 1200 GW owners may need this information sooner than later, nothing lasts forever.

The basic mechanical maintenance of the '85/'86 FI models is not an issue, the CFI system unless modernized can be an issue. This could be mentioned as being true for the carbureted models as well.

Cheers

[Rednaxs60]

Posted this in a thread on the Classic GW forum. Thought it might be interesting.

Researching coil dwell and spark duration. This subject, specifically coils, is queried and commented on on most forums when older motorcycles are involved.

The engine tuning software, Tuner Studio (TS), permits the user to input settings for coil dwell and spark duration.

Coil dwell is simple, amount of time needed to bring the coil to the optimum coil charge for the engine in question. In a distributor type system, this is the time between each corner of the distributor shaft when the points are opened allowing the coil charge to go through the spark plug to ground, igniting the air-fuel mixture in the engine cylinder. The spark duration is the time the points are open, extremely quick. The coil and spark duration are calibrated for a specific engine.

I have commented on coil changes in that a coil will provide adequate engine operation, but the coil internal wiring must be the same. Using a coil that is not exactly the same does impact on engine power and fuel economy.

Changing a distributor system to an electronic ignition module is a good upgrade but you must ensure that the coil dwell period and spark duration is maintained to continue having optimum engine power and fuel economy.

Along came EFI where the OEM tuned the engine to achieve the same aim as with a distributor type ignition system. The OEM, very guarded in how it did the work, could after installation, adjust the coil dwell and spark duration if required. The OEM did not provide the owner with the tool(s) to do this, but most of us just want to start the engine, put the vehicle in "D" for ditch and go.

Bring on aftermarket/replacement ECUs, and carburetor to EFI conversions. The owner now wants to control the engine's destiny.

Aftermarket/replacement ECUs generally have engine tuning software that allows the owner/tuner to calibrate the engine tune, and two of these parameters are coil dwell and spark duration.

There are a lot of coils on the market and some will have the data required such as dwell time, but a lot will not. A caution regarding this is that all coils regardless of what the coil is purported to do and what it is for are not always created equal. Internal wiring sizes, primary/secondary, can be smaller or larger, changing the coil charge/discharge characteristics. The time required to discharge the coil, spark duration, may or may not be known.

The coil discharge through the spark plug regardless of spark duration must be sufficient to provide good air-fuel mixture burn. A coil that does not fully charge will not provide a long enough or hot enough spark to completely ignite the air-fuel mixture, or be able to bridge the spark plug gap. Too much coil charge - dwell time too long, and the coil may not discharge fully, and be too much and exceed the spark plug electrode gap. Too much coil charge can overheat the coil and cause it to fail.

The issue with a coil is the primary coil current. The coil resistance remains the same as does the voltage. The coil primary current is dependent system voltage, resistance constant.

An example I found on-line.for a specific coil indicated that for a coil primary circuit current of 2 amps, the spark generated only bridged a spark plug gap of 5 mm. For the same coil, a primary circuit current of 7 amps resulted in the spark bridging a spark plug gap of 22 mm. To achieve this variation of current in this specific coil, the coil dwell time had to be increased by over 3 ms indicating how critical correct coil dwell time is.

For the specific coil example, spark duration was also investigated. Spark duration for a primary coil circuit of 2 amps indicated that the spark duration was only 0.56 ms, whereas a primary coil circuit of 7 amps was 1.4 ms.

The coil driver is part of this equation. Two types available; "closed loop" electronic ignition module - no ECU dwell map, or a mapped dwell - ECU controlled.

The "closed loop" modules monitor the coil current and adjust the dwell time to ensure the target current level is always achieved, something like an alternator monitoring the electrical system voltage. These modules generally use 7 amps as the set point to be maintained.

ECU controlled modules use the settings in the engine tune to control the coil dwell (charge time).

I have thought about this regarding the ability to input a setting for coil dwell and spark duration. From my layman's perspective, setting the spark duration at say 2 ms, and not having enough dwell time to have the correct corresponding coil charge, is not advantageous. The coil dwell time must be adequate enough to provide a discharge spark for the required spark duration.

This can be achieved by bench testing, requiring instrumentation and well thought out procedure, or by experimentation on engine. Most of us will try the experimentation route.

I have investigated a new timing light. The options are quite extensive with varying prices; however, I did find one timing light that does more than indicate engine ignition timing. The Snap-On Ultra Light EETL500 - not inexpensive. It can measure engine RPM, ignition advance and dwell, measures burn voltage and burn time, checks current battery state, measure and display kV readings (view individual cylinder firing voltage, perform snap throttle and coil stress tests), and diagnosis faulty ignition wires/plugs/modules/coils. Will not; however, make lunch.

This timing light has a focus on the hot rod and car enthusiast group.

Additionally, I have been doing on-line research and have found a few tidbits to support the above informatiuon.

I have been querying the coil-on-plug (COP) dwell time and spark duration for a COP. The COP dwell time is recommended to never be lower than 1.5 ms.

Jury is still out on the COP dwell time, but I will be using the finger test to determine an appropriate dwell time. if the COP temperature using the finger test allows me to touch the COP without burning my fingers, all should be good.

I have viewed YouTube videos regarding testing for this and may give bench testing a go.

I have increased the COP dwell from 1.6 ms to 2.0 ms and think I have seen a difference in engine operation. The spark duration is set at 2.0 ms. I will be increasing the COP dwell to 2.2 ms, use a small temperature gun to check COP temperature in conjunction with the finger touch test, and make sure I do not overheat the COP units. Increasing the COP dwell time, increases the primary current into the coil.

Cheers