1985 GL1200 Limited ECU Replacement/Upgrade - Part 2

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TPS settings updated

Timing set - initial with cranking timing set to "0" degrees, second check with cranking timing set to "10" degrees. Read about the older timing lights. If the timing light does not have a setting for 2-stroke or wasted spark, there may be a requirement to double the advance setting to get the correct timing. Had to do this with mine.

Non-return valve installed between FP and fuel filter. Installed the FP gauge.

Pressurized the fuel system manually, have found the issue. Manual pressurization allowed the system to go to max pressure relief on the FPR. The FP is capable of upwards of 65 PSI. The FPR seems to max out at 3 bar with the engine not operating, then relieves back to the tank. Let the system bleed out overnight, but it still registers 10 PSI. Thinking the fuel system is at atmospheric pressure so no more flow, and not enough pressure to force the fuel out the fittings.

Have a small fuel leak at the gauge fittings. Will correct then pressurize fuel system for further investigation. Fuel gauge is a good addition to the mix.

Tested coil spark. Better spark than with the older OEM coils. Got my fingers too close to #1 plug cap before everything settled out, got zapped. Never happened with the OEM setup.

Fellow on the Speeduino forum gave his pearls of wisdom regarding coils: "The energy in a coil is the square of the current multiplied by the inductance. Modern coils have a low resistance which allows higher currents and more energy. Electronic control of the dwell time means they are energized for the minimum period necessary minimizing heat, spark plug gaps are generally 38 or 40thou. 3 Ohm coils were the norm back when contact breakers were used, dwell times were huge at low RPM and and if the ignition was on with the engine not running the coil had to be able to withstand the coil being on permanently, spark plug gaps were usually around 25thou. Ballast resistors were brought in to allow the use of lower resistances to improve the spark during starting when the battery voltage was lower, they don't offer any other advantage. With electronic control lower resistance coils were able to be used and these give higher energy in a smaller package. 3 Ohm coils will work with Speeduino, so will lower impedance coils, you just need to set the dwell times appropriately, lower impedance coils will give a better spark."
Quick update. Fuel system has come under scrutiny - when has it not. Loosing fuel pressure meaning air in the fuel rail, not good when starting engine. Non-return valve in main fuel line - no fuel should be leaking back through the FP. This will be last system check after I replace fuel pressure relief (FPR) valve.

Checked the cylinders this morning, all dry, injectors appear to not be leaking.

Pressurized system, had fuel shut off valve closed - non-return valve in line, pressure dropped from 36 PSI to 20 PSI in 2 hours 15 minutes. Pressure bleed has almost stopped but do expect the pressure to be at about 14 PSI in morning. Appears that this FPR valve - original, has a very weak internal spring but is somewhat effective at the 20 PSI range. Have a new 3 bar FPR that I will install this week.

Getting closer to a resolution.

Will start looking at how to install the new coil pack where the OEM coils are.
Update. Tested fuel system for pressure loss. Thinking maybe injectors, but blanked the injector ports and same issues occur. The OEM fuel pump does not appear to have an integral non-return valve:

Injector ports.JPG

Rebuilding the fuel system. Swapping out the very large OEM style fuel filter for a modern 40 micron dwarf. Will be using a non-return valve, and going to a -6AN fitting system. Have been researching aftermarket fuel pumps that will work, some have non-return valves incorporated some do not.

The fuel pressure regulator is in question as well. Injectors are flow tested at 42 PSI for a flow rate of ~284 cc/min. The OEM CFI system operates with a static fuel pressure of ~36 PSI that drops to 32 to 28 PSI when engine idling - the four injectors flow a lot of fuel. Wondering if it would not be better to have the fuel system pressure more consistent around 37 PSI because the new ECU will be using the injector flow rate of 284 cc/min for the tuning calculations, otherwise smaller injectors would be more appropriate.

When I view YouTube videos that are applicable, find that the expectations are different than those in 1985. The fuel pressure expected is greater than the 1985 Honda OEM CFI requirement, and that this pressure should be constant during engine operation are the two most relevant issues. The next issue is that the OEM CFI system design takes into account these pressures, the new ECU probably can, but don't believe this to be best practice.

Have been researching adjustable fuel pressure regulators. Inexpensive versus expensive. Reviews and such all over the map. Will be considering. In for a penny, in for a pound.

Will be changing the fuel pump to the airtex external E8312 fuel pump for a couple of reasons. This fuel pump apparently has an integral non-return valve, and -6AN banjo fitting can be used. The OEM fuel pump outlet banjo fitting is designed specifically for the OEM fuel pump outlet, different from a standard banjo fitting and because of this the -6AN standard banjo fitting cannot, or should not be used on the OEM fuel pump. This banjo fitting has a 15 mm and 12 mm openings because of the fuel flow out of the fuel pump.

Fuel Pump Oulet Banjo Fitting.JPG

Looking at this banjo fitting the opening is 15 mm and the opening at the back is 12 mm. Specific design for the OEM CFI application.

Fuel Flow.jpg

The fuel flow out of the fuel pump at #1 impacts on the fuel banjo nut at #2, then back to the fuel pump outlet banjo fitting through holes at #3. Fuel flow is then out through the banjo fitting to the system, slightly different from more modern fuel pump(s) and fittings. Layman's terms, fuel flows out the end of the banjo spigot, then flows back and out the banjo fitting

Will be looking into upgrading the fuel supply to the aftermarket fuel pump to include a fuel filter of say 50 micron size and using the -6AN fittings if possible.

The is the OEM fuel filter on the right and the aftermarket alternative from Beck Arney on left:

Fuel Filter comparison.jpg:

Pictures of the new Russell fuel filter, a peanut compared to the OEM size, but will do the same job. The fuel non-return valve from Russell is the same size as this fuel filter. The smaller size allows for ease of installation, and where these can be installed:

New Fuel Filter 1.JPGNew Fuel Filter 2.JPG

OEM fuel system was a bit overkill by today's standards. The new fuel filter has a 40 micron screen that can be cleaned and/or replaced with a finer filtering screen.
Red,in my experience,airtex electric pumps suck.i like carter or ac/delco.good luck with it.
The Airtex is what I have on hand. Had it installed before and it was working fine. The Airtex lets me use a standard banjo fitting that can be barbed or have an "AN" banjo fitting on the outlet. Once I've plumbed this in, change out will be quite easy. The inlet to the Airtex pump does not support the "AN" style fitting(s), will need to use the cone filter that is in the OEM FP. Would like to plumb the inlet with an in line filter such as the 40 micron I am installing on the fuel system side.
Everything is now in for the fuel system upgrade, looking forward to getting it done.

Have a couple of new(er) coil drivers for use, and may use the Bosch with the Opal Corsa coil pack, but also have (just in) the GM 4 pin HEI coil drivers that I want to use with the OEM coils. Should fit where the OEM spark units are installed, and from the Speeduino forum these four pin modules limit the maximum coil current to under 6A and protect the coil if the dwell is too long, but will get hot.

GM HEI 4 Pin Coil Driver 2.jpg

It would be interesting to trial these coil drivers on the OEM CFI system, but I have changed a few items that would require me to do some changes to get back to the OEM configuration. Want to trundle on and get this done.
Took some time out to do an article on the '85/'86 CFI system that I have probably done before, but I have changed it a bit. It's good for me as I keep my thoughts organized, and each CFI part/component is making more sense as I progress with this project. It's in PDF format, and it will make for some good bedside reading, guaranteed to help you get to sleep. Comments are always appreciated.



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Another notch in the belt. Tested the diaphragm fuel pressure regulating valves, OEM original on right, and Delphi FP10490-20822 3 BAR. Had the Delphi return connection straightened to fit:
FPR Valves.JPG
Used a scientific apparatus, water in the hose - connected the compressor, used the compressor pressure gauge to determine FPR valve relief pressure:
FPR Test Rig 1.JPG
The OEM original FPR valve held up to approximately 37 PSI, not bad for the age. The Delphi only made it to 30 PSI.

Connected the adjustable fuel pressure relief valve to the test rig:
FPR Test Rig 2.JPG
Adjusted this FPR valve to approximately 43 PSI. Flows well when adjusted pressure is exceeded. Install space is limited but install will be done.
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For those of you who may want to add an adjustable fuel regulator to your '85/'86 CFI model, you will need to have an adaptor that goes between the fuel rail and the FPR. The fuel rail needs a spigot style adaptor that is 10 mm in diameter before the o-ring is fitted. Found one and have it installed. Amazon site: https://www.amazon.ca/dp/B08CHJB79J?psc=1&ref=ppx_yo2ov_dt_b_product_details
Fuel Rail Adaptor.jpg
Update on the project. Have mentioned most of this in previous posts, just a short recap.

Installed the upgraded fuel system, aftermarket fuel pump to accept a standard fuel outlet banjo fitting. Using AN6 fittings as well as fuel hose barb connections. The AN6 fittings are good and can be disassembled and used again. The adjustable FPR uses AN6/ORB8 fittings.

Installed a non-return valve in the fuel hose from the fuel pump to the fuel rail. No fuel returning back through the fuel pump. Have installed a new Russell 40 micron fuel filter. Would like a new filter on the inlet to the pump, but not a lot of space to install.

The adjustable FPR is not that small, but the space needed for the AN6 fittings is significant as well. Have to be inventive where to place the FPR.

The FPR is bleeding fuel system pressure, but have found that this is a common occurrence with the less expensive adjustable FPRs, and even the more expensive models such as AEM, Aeromotive and such. Thinking taking it off and apart for a check and possible cleaning may be in order - the AN6 fittings make this easy.

I would like to relocate the FPR to the space where the OEM fuel filter was located for aesthetic reasons. Can locate the non-return valve and filter so that these are out of the way.

These are pics of the fuel system installed:
FPR Install.JPGFuel System Upgrade 3.JPGFuel System - Left Side.JPG
I've located the new coil driver, and have it wired:
Coil Driver Install.JPG
The coil pack is installed. Will be doing some work on the coil pack bracket:
Coil Pack Install 4.JPG
Have some work to do on the car, and a busy family schedule this weekend. Will check timing and spark early next week. Plan is to have the engine started and initial tuning done next week.

Fuel pressure needs to be set. I've mentioned that the OEM injectors flow 280 cc/min at 43 PSI. To get this same performance expect that the fuel pressure needs to be set at 50 PSI with the vacuum hose disconnected.

The 280 cc/min is an important setting in the ECU software in that it directly affects the Required Fuel (RF) setting. The RF setting is used to determine how much fuel is required for one engine cycle - 720 degrees, and affects the injector pulse width.

Using 43 PSI to have the injectors flow 280 cc/min should not be an issue, have to adjust the VE (volumetric efficiency) table to get the appropriate fuel injection for the estimated air mass that the engine is using at a specific point in time - first order of business. The aim is to get a stable base idle with a good AFR and MAP value.

I believe I have mentioned that I have removed the 5K OHM resistor in the plug caps. The new vacuum mixing chamber is installed, a bit more fiddling needed to set it in place.

More to follow.
Need a bit of assistance in reading the timing marks. It was very simple with the original ECU, set the timing belt and crankshaft marks to align everything to #1 TDC. Now reading the manual and notice that once this is done, you use the "F1" crankshaft mark to set the timing for idle. Can't adjust anything with the FI model so never concerned myself with it.

With the new ECU, first order of business is to set the timing, right after verifying that there is spark to each cylinder.

Having aligned the crankshaft and timing belts using the "T1" crankshaft mark, I want to set the timing for engine operation. Recommended way is to remove plugs, disconnect fuel pump and injectors, turn over the engine and use timing light to set timing. Initial trigger wheel setting is done.

When I spin the engine to check timing, I can lock the ignition at a certain degree to check the timing. I am using an ECU timing setting of "0" and "10" degrees to verify timing. From what I have read in the manual, I surmise that when I do this I should be setting the timing to the "F1" mark. If this is the case, the timing is spot on.

Comments, recommendations would be appreciated.

Sometimes the simplest issues are the most confusing.

133 posts and still the bike is not on the road. There is a lot to be learned about this EFI world. Waiting on a set of injectors, sent out for cleaning, flow and leak testing as well as data about the injectors.

Cleaning up small items, wiring placement and such. Have timed the engine using the "F1" mark on the crankshaft. Fuel system needs more attention, but is good enough for now. Shoe horned the new coil pack into place. Have thoughts on the support bracket that needs to be addressed. Time to push the start button.

I have come to a realization that the OEM CFI system is much like the Apple computer, a box and in that box are the parts/pieces of an EFI system that have been chosen to work as an integral unit. Honda knows/knew what the design requirements were, chose the appropriate components/parts, programmed the ECU and voila, the engine is alive and operating well.

I was in a mindset that was counterproductive. I was trying to apply what I knew about the CFI system to the ECU replacement/upgrade project. You cannot do this. The only similarity is that the EFI components are already in place.

Timing is totally different. Timing an '85 FI model is aligning the crank and camshafts using the crank "T1" mark, button the engine up and push the start button. The new ECU with a different trigger wheel needs the timing calculated and the ECU tuning program setting to be input. The engine idle is ~1000 RPM +/- 100 RPM. Why? Is it because of the Stator? 1500/1800 GWs idle at ~900 RPM, the 1200 can as well, especially if you have done the external alternator mod. Setting the TPS for the new ECU. What is the correct calibration - unknown. A lot of new issues using an existing FI system.

I have started, again, a document regarding my journey down this rabbit hole. Thought it would be a short dissertation, but in my need to expound on the project, it has grown into a 50 page document and I'm not finished - thinking I have several reviews to do. It does keep me busy, and I am slowly piecing together the EFI puzzle, who does what to whom and the likes.

I find this very interesting. The more I understand about the EFI system, the more comfortable I am with this project. Need to understand what the various parameters are and how these are used by the ECU so that I can properly tune the engine.

Just finished up the research on the Spark Duration/Burn Time, not a lot mentioned in the tuning software information, or the Speeduino manual.

I sleep well at night and this research fills in the down times when I'm waiting for items. Have the Spyder to ride and the Mrs reminds when we should go for a ride.
This post is about the research I did regarding Spark Duration, also called Burn Time. Has to do with coil(s) - dwell time, spark plugs - burn time/spark plug electrode gap, and the distributor/electronic control units. Took me further down this rabbit hole such that I have included information I have read about the venerable spark plug, an innocuous little item, but extremely important. This information may be f interest to some, but not others. It may be applicable to some, but not others.

As mentioned, I have included information about the spark plug. This is because many ask about a recommended spark plug gap for their application, the size and shape of the spark plug electrode, and are the newer spark plug design worth the expense.

As you know, I have mentioned I am an economical Canadian, meaning I'm cheap. I want the best bang for my dollar, and in this regard, information that I can understand that will help me is invaluable.

I have attached the file regarding Spark Duration for your reading pleasure. As always, this document and the information provided is my understanding of the issue.



  • Spark duration - PDF.pdf
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More research done and this time regarding coils, spark units (coil drivers) and coil dwell time. It's interesting information, will probably be like school and past work where the information was required, but now, only if needed. Looked into the theory and practical issues.

This information does answer some distant questions I have thought about regarding the many forum threads regarding upgrading/changing coils, installation of CD ignition systems and such.

Many factors influence the correct selection of coil for the application such as turns ratio, coil inductance, and input voltage. These factors affect the coil operation in the ignition system, and potentially engine performance. There is information on CD ignition systems and how coils should be "matched" to the specific CD unit.

Coil tuning, yes, I have found information regarding this topic. Never heard of it so had to go look for information regarding it. It's similar to choosing spark plugs, and experimenting to get the best coil for your application.

The attached document is the Reader's Digest information I have, not everything I've read and found, but enough to give me a better understanding of the ignition coil and coil drivers. YMMV!

Enjoy, have a good read, questions will be asked later.:LOL::cool:


  • Coils - 21 May 2023.pdf
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Good YouTube video on acceleration enrichment (AE), the history of this and the challenges even today. Watched it last night on YouTube - Dr Jim Cowart - IC Engine and Transient Enrichments.
Good information regarding AE, specifically on initial start in the morning and after engine is at operating temperature. Talks about fuel puddling/wall wetting, applicable to carb and EFI. He imparts a lot of information in 15 minutes. Have a view.
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This information I'm posting is what I need to read and understand for this project. I will find more information regarding AE, but have to find out about "Tip In" as well.

Still waiting on the fuel injectors, at shop for servicing.
Have to keep the momentum going. After reading this information you may wonder why then, should a person think of changing one of the wonders of modern motorcycle technology. The main issue, is you cannot change the CFI system. You have to let it go on until it finally goes the way of the dodo bird. After some 38 years, time for an upgrade.

History of the CFI System. Don' think I posted this information before. It is from the Motorcycle Fuel Injection Handbook by Adam Wade. He discusses the different EFI system back in the 1980 to 1990 era. he saved the Honda CFI system for the last because of it was extremely unique and well ahead of its time. He did miss the 1985/1986 Gold Wing FI models.

Too bad cost had to enter into the equation.

This is the information in a PDF file, enjoy the read.


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