1985 GL1200 Limited ECU Replacement/Upgrade - Part 3 - Road Trials

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A short follow up regarding spark plug reading. Took the last road trial plugs apart, and the pugs are an interesting read. Looks like I can lean out the air-fuel mix and the timing is bordering on too advanced. Now I have a good place to start from for the engine tune. Honda did a good job on practically designing and building a balanced engine and because of this, engine issues are hard to feel/spot. Here is a picture of the plugs taken apart. You have to break a few eggs, to make a good omelet.
Spark Plugs Apart - Fuel line.JPG
Plug Case - Timing Mark.JPG

Need a couple more road trials with used plugs to determine if the "readings" are correct, then switch to new plugs for a few road trials.
Second road trial and looking at the plugs. Engine tune is firming up. Took another set of plugs apart. #1 cylinder is a bit different, and the ground straps indicate that the engine timing may be advanced too much. Reviewed the data log and the engine timing is off. Redid the ignition timing map and made it a new "wedge" table. More riding to be done. This is the picture off the plugs to date. Dual picture, top is from the first plug destruction, forgot to label plugs, bottom half is from yesterdays road trial:
Plug Data.jpg
#1 cylinder is nt what I expected to see. Was changing some fuel values. Another road trial to be done.
Don't know what the issue is, more road trials and spark plug destruction to follow. Depending what I find from the next couple of road trials, this investigation may be a good precursor to individual cylinder fuel control (ICFT).
I'm mentioning plugs and coils because there is very little if anything an owner can do to the 1200 engine regarding fuel and timing management. Lots of threads about modifying

Timing is set for all 1200 engines and an owner cannot change this. The fuel management of the FI models is set, not able to change. The 1200 carb models can be adjusted a bit, the FI models - not. The 1200 carb models can be adjusted for fuel in that you can balance the carbs and hopefully all is well.

Thinking that reading the spark plugs as I have mentioned, may provide good results for tuning the a 1200 carb engine fuel supply, and if necessary, balance the individual cylinders. Bit of a process, but if one cylinder is running rich or lean, the process of reading the plugs may be of assistance. Once the cylinders are balanced, each cylinder will provide the same amount of work, and the performance and operation of the engine should be improved. This should be valid for the SCC.

Old style reading of the plugs for carbed GWs can also provide guidance regarding carb jet sizing. It's good to have recommendations, but need to do a bit of scientific investigation as well even if it is old school testing/tuning. Smaller jets - lean fuel mixture (not good), larger jets - rich fuel mixture (PITA). Air-fuel mixture just right - engine happy, best performance you can get. The trick is finding the "sweet" spot with carb jetting, and how to go about doing it.

Coils, dwell time for the 1200 coils is controlled by electronic units, can't change this so, bite the bullet and find coils that are the same spec and require the same dwell time.

The 1000 and 1100 GWs are not newer electronic technology, so learning how to read the plugs and using this information to set up the engine could/will be beneficial. Takes most of the guess work out of tuning the engine. If you are going to retrofit an older GW, do a SCC, and such, recommend taking a bit more time and look into the plugs and coils.

Engine tuning today is software based and you look at data. This is good and does provide a level of tuning that is far beyond what was used in the more basic times; however, we must/should not loose sight of the fact that not everything can be solved using software packages/applications. Tools are just this, tools. Not one tool is the end all, be all, but all tools, new and old, have a place in the overall system.

Here's a video regarding [plug reading by an older fellow:
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Yesterday's road trial (11 Mar 2024) was primarily engine timing, no VE changes. Adjusted COP dwell a point or two. Engine tune is coming into focus. Looked at the tables and looked at the 3D maps. The ignition table is looking good, but the VE table is rustic to say the least. Looked at the data log and it confirms where there is VE table tuning to do. Smoothed the table (expect further changes) to get rid of some of the rich feeling swings. Will be testing in the near future. I modified the VE table with the thought that as the engine RPM goes from a low RPM to a higher RPM, the VE table cell values should increase, and when the engine load goes from a low to high load, the VE Table cell values should increase (adjusted the cell values manually - table smoothing still not quite understood).

Here's a pic of the tables in 3D view:
VE-Spark Tables 11 Mar 2024.jpg

VE-Spark Tables 11 Mar 2024.jpg (82.81 KiB) Not viewed yet
Noticed that the TPS signal is not what I would expect. For example, engine RPM 2800 or so, no TPS signal. Will be investigating.
Next tidbit for the '85/'86 GW FI Model owners, coolant temperature. Coolant temperature affects a lot of features in the OEM CFI ECU. It directly affects Cold Advance (ignition timing during engine warm up). Some of the other features are Cranking Enrichment - the fuel the ECU estimates to be needed as soon as the engine starts, Priming Pulse Width, the fuel injector pulse width for the amount of fuel needed to operate the engine, after start enrichment (ASE), the amount of fuel delivered to the engine on start so that the engine doe not operate in a fuel lean condition, and warm up enrichment (WUE) that adds fuel to the required amount IAW the VE table values so that the engine warms up with an appropriate amount of fuel to prevent a fuel lean condition during warm up. Most EFI systems old/new have these same features.

What does engine coolant temperature have to do with this thread? The engine is designed to operate at approximately 85 degrees C, fan comes on, engine cools, fan goes off, cycle repeats itself. The above mentioned ECU features that rely on engine coolant temperature, can cycle on/off depending on the engine temperature. Four bars on the dash temperature gauge is approximately 60 degrees C, 6 bars is approximately 85 degrees C. If the ECU programming is such that the above features need to have approximately 80/85 degrees C engine temperature to be "OFF" (can't confirm, but it is a reasonable expectation), If the engine coolant temperature is less than this, the above ECU features may be enabled and additional fuel is added to the air fuel mixture having the engine operate in a fuel rich environment. This could mean fowled spark plugs, poor fuel economy and other issues.

What can be done about this, absolutely nothing regarding the ECU programming; however, let the engine operate at the 6 bar - 85 degree C level as much as possible, that's why a rad fan is part of the package. Nothing can be done when riding on the highway if the engine operates in the 4/5 bar range with the rad fan OFF.

The coolant temperature sensor is just one of the EFI components that is always considered by the ECU programming for the engine air-fuel mixture.

Well, the coolant thermostat should close below ~185 F and open at about 190 F. Fan or no fan. Of course, with no fan and to motion, even with the thermostat open the temperature will continue to increase.
Pidjones - agree wholeheartedly.

The coolant specs for the '85 FI model is that the thermostat opens 80-84 degrees C (176-190 degrees F) and fully open at 95 degree C (194 degree F). With the tuning software I can see the engine coolant temperature cycling and the rad fan starting at approximately 85 degree C, 6 bars showing on the dash temp gauge. The rad fan has always come on in the 6 bar range.

The purpose of my post regarding engine coolant temperature is about what the engine coolant temperature impacts on. There have been queries about the engine coolant temperature and what it should be and when for GL1200 carb and FI models.

Inlet air temperature (IAT) affects fuelling as well, the colder the air coming into the engine the more fuel enrichment is done. The combination of IAT and CLT on fuelling especially on cold start and engine warmup is a balancing act of which I have not addressed as of yet. These sensors can also affect the fuelling if either sensor temperature goes past what is considered a normal engine operating range.

Reading spark plugs has become a pet peeve for me. Pull the plugs after each road trial. Timing is a focus at this time, especially the colour change of the ground strap. Wasn't seeing any colour change and IAW what I have read, this means the engine timing is too advanced. Last road trip started to retard the timing at various RPM /load levels in conjunction with tuning the VE (fuel) table. Finished the road trial, pulled the plugs and there was a colour change that indicates timing may be starting to be a bit much on the retarding side - will be monitoring.

Post these little tidbits so that others, if so desired, can better troubleshoot their FI models, symptom-culprit issue. Best to know what is affected by a faulty component so you don't go down the proverbial rabbit hole. This component affects "X". Is the component in spec, no ECU error codes, can you change the ECU programming - no, onto the next component and so on. Eventually you get to the "good enough" mindset, or you go more exotic.

As an aside, I have noticed that there are three components to any engine tuning be it carb or FI. These are fuel economy, power/performance, or a balance of the two. Picking the appropriate one for your requirements will steer you in the direction you need to go.

If you are doing road rallies, track days - fuel economy is probably not high on the hit list whereas GL1800 owners are installing a different rear drive unit that drops engine RPM in all gears and apparently increase fuel economy.

Enough for today. Have to get ready to get stuck like a pin cushion for bloodwork - hate needles, and maybe another road trial.

Happy to announce that after many road trials have an engine tune that is "not bad" (perspective) based on tuning the VE (fuel) table and having a "wedge" table for ignition timing. Tuning a motorcycle is the same as a car, but takes longer as table cell values, IMO, are done in single point increments and generally based on the "seat of the pants" feel. Changes are also done when riding based on smooth acceleration, and when you transition through an engine RPM/load combination and "feel" something. You will probably slow down and try to recreate the same combination and decided if there is a cell change to be done.

Going to do a road trial and not touch any of the engine tune settings so a clean data log can be viewed to determine if some areas need to be adjusted. Looking for potential misfires.

Researching the next phase, that of ignition timing. Using a wedge table at this time. The cell values are estimated and each column is the same value and the values increase from a low RPM to a higher RPM, example:
Spark Table Example.jpg

The spark table will now be adjusted for the various engine RPM/load combinations. As the ignition timing is advanced - one degree at a time, I should see the AFR reading start to lean out. If there is no change, r not much of one, I will revert to the ignition timing I started with then move on to the next block of cells. Will be careful to stay away from engine knock - too lean in the VE table with too much ignition timing advance.

I will be looking at the base engine timing. This has been proposed on the Speeduino forum, and in other literature I have found 0n-line. This is where you have set the initial trigger angle for #1 TDC, and then started and carried on with engine tuning. I will be doing a specific synchronization between the OEM recommended idle timing of 10 degrees BTDC, and what the ECU is seeing to finalize the ignition trigger angle.

Once the VE (fuel) and spark (ignition timing) tables are set, I will be able to populate the AFR table. The AFR value(s) that are specific to an engine RPM /load range are determined from well adjusted VE and spark tables.

I mention above that the AFR reading is used to indicate whether the engine is in a lean or rich fueling condition when adjusting the ignition timing. This is correct because the O2 sensor has been disabled and the AFR table does not impact on the tuning being done, but it does indicate what the AFR is for any engine RPM/load combination. If the O2 sensor was enabled it could be affecting the tuning being done; ie, wrong AFR setting can change the engine tune.

To summarize the tuning process to date:

1. Set initial trigger angle, set base timing to synchronize ECU and engine, and finalize trigger angle - can be done initially or later on. Engines will operate in the 10 to 20 degree range BTDC at idle;
2. Have the VE and spark tables set to allow for engine operation;
3. Set the base idle where the engine is operating in a smooth and stable condition;
4. Do road trials and adjust the VE table to suit;
5. VE table adjusted, adjust the spark table to suit;
6. Populate the AFR table.

There are other settings that need to be finalized such as coil dwell, spark duration, voltage corrections. These are adjusted/set as concurrent activities.

Getting there. Cheers
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I did not fully describe the concept of base ignition timing. It is necessary to decipher/sift through all the information available to get an understanding of what you are searching for to determine a way ahead. The tuners out there that have done this for a while are quite skilled, but do not always articulate what is meant as good as one would like.

This concept struck a cord with me in that I have read where other neophytes were having issue(s) with engine timing especially when transitioning to sequential fuel injection.

This information is available from different web sites and is articulated in different ways, but the best I found is from DIYAuottune (summarized below): https://www.diyautotune.com/support/tech/other/base-timing/.

Base timing is synchronizing the ECU with what the engine timing is doing. It is intended for a dual wheel application - cam and crank shaft trigger wheels, not a single trigger wheel - missing tooth install. If the trigger angle set with a single crank or cam shaft trigger wheel - missing tooth, then the person needs to revisit the calculations and/or trigger wheel settings.

The synchronization between the ECU and engine is what I would think is to determine if there is an ignition timing offset. You set the initial trigger angle at #1 TDC. You then take a second known OEM ignition timing setting and adjust (if necessary) the trigger angle to match. This may be a point or two in either direction.

The 1200 engine as with the 1000/1100, have two known data points, the "T1" for #1 TDC, and "F1" for idle timing at 10 degrees BTDC. Using these two marks you should be able to calibrate the ECU to engine timing.

This is similar, IMO, to calibrating the various FI components for say CLT/IAT and voltage.

The article from DIYAutotune mentions that going forward after the base ignition timing is set, when the ECU commands XX degrees of ignition advance, you know that’s what you’re getting. This ensures that your advance curve occurs as you’ve entered it into the ignition timing (spark) table.

Hi Ernest! At this point, I have to say you have more than likely performed more engineering work on this than Honda did when they developed the system oh so many years ago! Always a good read and love the drive to get it right!
Gentlemen - thank you. Not about patience - the old saying "patience my ass - I'm going to kill someone". Anyone remember this off the cuff saying? I like to know what the issue is and wh is it supposed to be this way. My partner Sonya's eyes glaze over whenever I show her what I am doing.

The issue with Honda is that there is no information available regarding these older GWs other than the manuals and the "by the seat experience", same for the newer ones as well.

This project has had me look into many different aspects that I might have known, or might have known but didn't know the why of it.

I will plug away at this and post what I learn as I go, as well as progress.

Next post will be on timing, advance or retard - that is the question, and how the VE table (this is an air table, not a fuel table) interact.

Engine Ignition Timing

There is a lot to this, but I will be as succinct as possible. Start at the top. Initial ignition timing – base ignition timing, call it what you will is ignition timing at engine idle. My research indicates this is what is meant. To set this ignition timing, you need to know the OEM setting. For my GW this is using the “F1” flywheel mark. Base ignition timing set and verified.

VE (volumetric efficiency) table. This is an air table. It represents the percentage of air being used for efficient combustion at all power ranges. I mention it’s an air table because a 1200 cc engine, my GW, at 100% efficiency uses 1200 cc of air at full power. If a VE table cell value is say 50, this is 50% of the 100% (1200 cc) and represents 600cc of air being used for engine combustion. Where does the correlation to a “fuel” table come from? The VE table cell value is used by the ECU when determining the fuel injector pulse width (PW). This calculation uses the calculated required fuel (RF) – the amount of fuel required for a single cycle, multiplied by the VE table cell value, and other component settings. It’s like a brand name such as Kleenex – all nose blow products can be categorized under one word/phrase.

First order of business is to get the VE table settings correct for idle to achieve lowest engine MAP for a smooth stable idle, at normal engine operating temperature. Once this is completed, you can tune the warmup fuel enrichment (WUE) quite easily – another story. For my GW engine, this point was where I was not “feeling” a difference in engine operation with the exception of exhaust “burble” (yes – this is a word in the engine tuning world). This sound can be related to that of a flowing creek that “burbles” – makes that nice sound that is so soothing. This sound is the result of some unburnt fuel flashing off in the exhaust.

Road trials to commence. VE table cell values are the first to be adjusted to get the engine to a good/better/best operation. Once you have done this to the best of your abilities (varies with expertise), start adjusting the spark (ignition) timing table. Where to start is the question. Needs to be careful – BTDT, in that you can “lean” out your engine and get engine knock quite quickly.

At a given air-fuel mixture, advancing the timing will lean out the air-fuel mixture, retarding the ignition timing will richen the air-fuel mixture. This can be seen with an O2 sensor if fitted.

What you are aiming for is to have all the fuel that is being delivered to an engine cylinder fully burnt and combusted at approximately 10 to 20 degrees ATDC. This value has not changed since ICE were invented and being used.

As I mentioned, lean/rich fuel mixture can be affected by engine timing. If you advance the ignition timing for a given amount of fuel, it can be burnt/fully combusted before the desired piston location of 10 to 20 degrees ATDC resulting in all sorts of issues such as overheating, poor fuel economy, low power and the worst, engine knock to name a few.

If the ignition timing is too retarded, fuel is ignited closer to TDC, similar issues can occur.

The aim is to try and get to the sweet spot of 10 to 20 degrees ATDC for the fuel to be fully burnt/combusted.

There is a “dance to be done when tuning the spark and VE tables. I have my engine VE table tuned fairly well, have that nice exhaust “burble” every now and then depending on engine RPM/load. I have started to adjust the spark ignition timing table to complement what has been done to the VE table. The question is which way to move the ignition timing – I now know the difference between the two.

I did some changes to the ignition timing and VE table before I completed my research into ignition timing. I changed a set of VE table cell values to the lean side, and at the same time, advanced the ignition timing for this engine RPM/load. The engine let me know quite quickly that I had done a NO-NO. Up to and after this specific engine RPM/load range, all’s good, but in that engine RPM/load range – engine knock. Quickly reverted back to what was until I returned home, then went looking for information on the issue.

I still have VE and spark table adjustments to be made, but not quite sure the range for each is. It’s a balancing act.

Once the VE and spark table cell values are set to the best of your tuning ability, you can start to populate the AFR table. Up to this point I could not, it would be a WAG instead of based on found data.

Note to the collective – this tuning is not over at this point. You will need to visit the three main tables as you go forward to ensure that the engine tune is not being affected by any new tuning feature you enable.

EFI conversion projects with aftermarket ECUs provide you with the tools to properly tune the engine. OEM EEFI systems may or may not allow this. Carbureted engine definitely do not. I have the flexibility to use these new tools to tune the GW engine and this is fantastic. I still use some old techniques such as reading spark plugs.

I mentioned in a previous post about reading spark plugs. I look at the plugs on the completion of each road trial. I can see the colour change in the plug ground strap that indicates which way the timing is – too advance or too retarded, or just right. I can see the air-fuel mixture on the air/fuel ring (base of the plug threads), notice it is not too black, but not as brownish as I want. This picture also shows some discolouration of the ground start at the bend. This is an indication of ignition timing - want the discolouration at the bend. Not too scientific or as accurate as with the new system, but good enough for the DIY aficionado. Advanced and the discolouration moves towards the plug threads, retarded and the discolouration moves towards the plug electrode:
Number 2 Ground Strap.JPG

I took two of the plugs apart to view the fuel ring at the base of the porcelain. The plugs I viewed indicate that the air/fuel mixture is pretty good, notice the air/fuel ring at the base of the porcelain:

Number 2 Air Fuel Mixture Ring.JPG

How does this affect the carb folks. I have mentioned that you can do a final carb balance by reading the spark plugs – getting the fuel amount correct by having a good air/fuel ring, and a good fuel ring at the base of the porcelain. You can adjust the engine ignition timing using the plug ground strap as a guide.

Ignition timing has gone by the wayside because of electronic ignition timing - most cannot be changed; however, with the advent of these new DIY ECU units that can do fuel or ignition or both depending on your setup, you now have products that can optimize your particular circumstance.

The GW engine that does not have electronic ignition timing can be adjusted somewhat. The issue I have is that using the engine timing mark viewing port is a PITA. Using a timing degree wheel at the crankshaft that matches the engine crankshaft #1 TDC (T1) and idle (F1) timing marks is much better.

Carb jetting - this needs to be done based on confirmed data be it with tuning software or using some older techniques for your riding area. You will not gain engine performance improvements based on gut feel or what would may be recommend. The engine will operate at best performance when the ignition timing and engine fuelling is optimal for your location. You will need to know what jets are available for your specific carbs.

The engine needs to be set to the OEM specs. Carbs balanced, engine timing as recommended, use the OEM plug recommendation. My research has indicated that these newer technologies do not provide the layman with any performance improvements. We are not that sensitive to perceived changes – save your money. Have 5 or 6 sets of plugs available for engine tuning. Clean the plugs regularly with a propane torch – does a great job, do not wire brush or blast the porcelain, damages the porcelain.

Now the fun begins. Do road trials, normal cruise type riding, keep the quick accelerations to a minimum. Treat all road trials like a leisurely Sunday afternoon ride. Come home, shut the engine off and pull the plugs. Look at each to determine what may be happening. If you cannot change the ignition timing, concentrate on the air/fuel mixture. Try to get the fuel ring at the base of the exposed porcelain, and the air/fuel ring at the base of the plug threads correct. This may entail adjusting the carb fuel bowl floats or changing the carb jetting to suit.

Engine tuning is not a quick and dirty process, takes time.

I’ve posted these links before, but a duplication never hurts:


Happy Tuning!

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