1985 Limited Edition 2022 Work Period

[Rednaxs60]

When I started to work on my ’85 Limited Edition back in 2016, I had a steep learning curve and made a lot of mistakes. Nothing catastrophic, but enough to screw up the OEM settings, one being how to adjust the TPS.

Have been adjusting the throttle position sensor (TPI) as it has a significant impact on what the ECU does on start and during operation. As with all learning curves, I thought that the TPS was the root cause for any fuelling issue the engine had.

Not a lot written about this except in the Supplement, and if not read and understood, can lead you down the proverbial rabbit hole - BTDT.

The Supplement has information on the TPS voltage calibration, 0.475 to 0.495 VDC, and you are not to adjust the throttle body lever stop screw. This is most important because the throttle body lever stop screw is set at the factory, and the setting of this screw is black magic, a black art so to speak.

These pictures show the throttle body lever, stop screw and the feeler gauge used:



The procedure to adjust the TPS is to bring the throttle body lever to the throttle body lever stop screw by backing off on the engine idle screw until the throttle plates are completely closed and there is no tension on the engine idle adjusting screw. As mentioned do not adjust the throttle body lever stop screw. The throttle body lever is only in place for the adjustment of the TPS.

When you back off the engine idle adjusting screw, count the number of turns so that you can duplicate and return the engine idle adjusting screws to the same position before starting.

Providing you can rotate and adjust the installed TPS, rotate it counter-clockwise, or clockwise as required to get a TPS voltage of 0.475 to 0.495 VDC. Tighten the screws, TPS value may change, and needs to be verified when tightened.

Take out the 0.110” feeler gauge, and reset the engine idle screw.

When this is done, check the TPS calibration. It should be the same voltage as when you calibrated the TPS with the feeler gauge. This is why the OEM mentions in the calibration procedure to not adjust the throttle body lever stop screw. May take you a few hours of calibrate then test to get the throttle body stop screw properly set if you move it.

This is important to understand. The setting of the throttle body lever stop screw, the calibration voltage, and the engine idle screw position are interrelated.

The voltage of 0.475 to 0.495 VDC is the voltage signal that the ECU uses to determine the position of the throttle plate(s) on engine start. Indicates that the throttle plates are in the closed throttle (CT) position.

I had thought that using the TPS you could impact on the injector fuelling profile. This may be possible/probable, but the impact of the TPS calibration is for the TPS signal to indicate that the throttle plates are closed, and with all electronic components, there is generally a range, be it small in this case, that is used.

You can check for wide open throttle (WOT) position by turning the throttle to the full open position and you should get approximately 4.5 VDC, may not. Mine is at 3.95 VDC. The important number is for the closed throttle position.

If there is a fuelling issue with the ’85/’86 FI models, it will probably be because one or more calibration settings are not in the required range(s).

The throttle plates on the ’85/’86 FI models are closed when the engine is at idle, or on deceleration. This is different from the carb models where the throttle plates are never fully closed.

When the computerized fuel system came into being with the 1982 CX500 Turbo and 1983 CX650 Turbo motorcycles, Honda realized that at idle and on deceleration the engines were being starved for combustion air.

To compensate for this the Idle Air Control (IAC) system came into being. This is a passive air system that provides air to the cylinders on engine start, and engine deceleration.

The Reed valves inject air into the cylinders on the downside of the throttle plates to keep the engine operating at idle. The effectiveness of the IAC system can be checked by removing the air hose from the air chamber to the IAC valve and putting your finger over the IAC valve inlet. The engine will stall.

It incorporates reed valves, operated by engine vacuum, and an IAC valve that is connected to the air chamber for combustion air.

The IAC valve opens and closes (never fully closed) by using a bimetal strip that when cold, has the IAC valve in the fully open position. It is connected to a DC power source and when the IAC valve bimetallic strip heats up it moves an internal component, partially closing the air inlet aperture. This IAC valve air inlet aperture is fully open on a cold start to provide sufficient air into the engine cylinders for proper fuel combustion at fast idle.

 

[mcgovern61]

My head hurts reading all the potential issue that could develop! (I think I will go and pull my single barrel updraft cast iron carb off my boat engine and clean the idle circuit. I think that is all I need to do, and all that I can handle at this point......)

 

[Rednaxs60]

Good morning Gerry. I'm with you on the head hurting issue. Would definitely like to find an '85/'86 FI guru out there but there are none. Have to do a lot of research to gather enough information to put together a good picture of what is happening and why things are done the way they are - a snippet here and there. Just mentioning that the OEM mentions to not do something brings to mind a question in that did the techs of the day know why the OEM mentioned this. For a person who will take apart a Gold Wing wiring harness, adapt a 1200 FI model fuse box into an 1100, and make it work is truly an artificer - a master of invention who uses ingenuity and the art of black magic to unlock extraordinary capabilities in objects for use. have a great day.

 

[mcgovern61]

Adapting the 1200 fuse panel was a blast! While it seemed complicated to look at, the simplicity of how the circuits worked (with better reliability and cleaner electrical power than the glass fuse block) made the whole project worth it! BUT, unlike an FI system with all of the potential tweaks and potential problems that can cause, my conversion was pretty straight forward.

 

[Rednaxs60]

Most people I converse with or talk to just shake their heads, eyes glaze over and topic drifts elsewhere. Have thought of taking the 1200 carcass wiring harness apart and determine if it can be optimized. Learning about the FI of the day has been very rewarding. My time with my father at his garage and being a marine engineering artificer in our Navy never prepared me for this. It is nice to have the time to look into all the idiosyncrasies that have been cropping up. Next big project for this bike is an aftermarket ECU, using the Speeding Project for this. Started this a while back but got sidetracked.

Still a bit jealous of your boat. Lived on a 40 foot Bayliner Bodega, did some rewiring on it, had a 30 foot Uniflite that I had to rewire, used a lot of BalMar components. Enough pontificating.

 

[mcgovern61]

FYI, we are selling the boat if you might be interested!

https://southjersey.craigslist.org/boa/d/millville-1956-chris-craft-24-semi/7544672955.html

 

[Rednaxs60]

Boats are going to be a phase that I have done, and moved on from. Do miss it every now and then. The Mrs gets motion sick even on our large BC ferries.

As mentioned have the TPS calibrated and the throttle body lever stop screw in the factory set position. I'm thinking I have this correct because the TPS calibration is 0.481 VDC and the TPS is 0.481 when the throttle plate(s) are in the closed position - closed throttle (CT). I still notice an unburnt fuel smell on cold start.

I'm thinking the TPS voltage at CT needs adjusting and is not exactly as that what I have mentioned in a previous post. Going to use a range form 0.55 VDC to 0.40 VDC.

Won't hurt to experiment and may stumble onto a good compromise.

Keeps the bike off the road for a few more days. If I can eliminate the fuel smell on cold start, maybe get a better fast idle response as well, adjusting the TPS calibration by varying the throttle plate stop screw position will be time well spent.

 

[Dusterdude]

Red,you are the guru

 

[OldWing SEI]

When I started to work on my ’85 Limited Edition back in 2016, I had a steep learning curve and made a lot of mistakes. Nothing catastrophic, but enough to screw up the OEM settings, one being how to adjust the TPS.

Have been adjusting the throttle position sensor (TPI) as it has a significant impact on what the ECU does on start and during operation. As with all learning curves, I thought that the TPS was the root cause for any fuelling issue the engine had.

Not a lot written about this except in the Supplement, and if not read and understood, can lead you down the proverbial rabbit hole - BTDT.

The Supplement has information on the TPS voltage calibration, 0.475 to 0.495 VDC, and you are not to adjust the throttle body lever stop screw. This is most important because the throttle body lever stop screw is set at the factory, and the setting of this screw is black magic, a black art so to speak.

These pictures show the throttle body lever, stop screw and the feeler gauge used:
View attachment 48919View attachment 48918


The procedure to adjust the TPS is to bring the throttle body lever to the throttle body lever stop screw by backing off on the engine idle screw until the throttle plates are completely closed and there is no tension on the engine idle adjusting screw. As mentioned do not adjust the throttle body lever stop screw. The throttle body lever is only in place for the adjustment of the TPS.

When you back off the engine idle adjusting screw, count the number of turns so that you can duplicate and return the engine idle adjusting screws to the same position before starting.

Providing you can rotate and adjust the installed TPS, rotate it counter-clockwise, or clockwise as required to get a TPS voltage of 0.475 to 0.495 VDC. Tighten the screws, TPS value may change, and needs to be verified when tightened.

Take out the 0.110” feeler gauge, and reset the engine idle screw.

When this is done, check the TPS calibration. It should be the same voltage as when you calibrated the TPS with the feeler gauge. This is why the OEM mentions in the calibration procedure to not adjust the throttle body lever stop screw. May take you a few hours of calibrate then test to get the throttle body stop screw properly set if you move it.

This is important to understand. The setting of the throttle body lever stop screw, the calibration voltage, and the engine idle screw position are interrelated.

The voltage of 0.475 to 0.495 VDC is the voltage signal that the ECU uses to determine the position of the throttle plate(s) on engine start. Indicates that the throttle plates are in the closed throttle (CT) position.

I had thought that using the TPS you could impact on the injector fuelling profile. This may be possible/probable, but the impact of the TPS calibration is for the TPS signal to indicate that the throttle plates are closed, and with all electronic components, there is generally a range, be it small in this case, that is used.

You can check for wide open throttle (WOT) position by turning the throttle to the full open position and you should get approximately 4.5 VDC, may not. Mine is at 3.95 VDC. The important number is for the closed throttle position.

If there is a fuelling issue with the ’85/’86 FI models, it will probably be because one or more calibration settings are not in the required range(s).

The throttle plates on the ’85/’86 FI models are closed when the engine is at idle, or on deceleration. This is different from the carb models where the throttle plates are never fully closed.

When the computerized fuel system came into being with the 1982 CX500 Turbo and 1983 CX650 Turbo motorcycles, Honda realized that at idle and on deceleration the engines were being starved for combustion air.

To compensate for this the Idle Air Control (IAC) system came into being. This is a passive air system that provides air to the cylinders on engine start, and engine deceleration.

The Reed valves inject air into the cylinders on the downside of the throttle plates to keep the engine operating at idle. The effectiveness of the IAC system can be checked by removing the air hose from the air chamber to the IAC valve and putting your finger over the IAC valve inlet. The engine will stall.

It incorporates reed valves, operated by engine vacuum, and an IAC valve that is connected to the air chamber for combustion air.

The IAC valve opens and closes (never fully closed) by using a bimetal strip that when cold, has the IAC valve in the fully open position. It is connected to a DC power source and when the IAC valve bimetallic strip heats up it moves an internal component, partially closing the air inlet aperture. This IAC valve air inlet aperture is fully open on a cold start to provide sufficient air into the engine cylinders for proper fuel combustion at fast idle.

Moin,
There must be an easier way to adjust the throttle screw. In production, they didn't have the time to experiment with it for long. Unfortunately, I have not found this setting value anywhere either. I guess we'll have to keep looking. On mine, the screw was also adjusted, but the TPS is still in the original position.

 

[Rednaxs60]

Had a friend measure the stop screw on an unmolested '85. This is a good starting point:

 

[Rednaxs60]

Have been doing some "housework", trimming the windows with door casing. Has a finished look. New blinds ordered.

While I do this, still ponder over what I have done to the 1200, and what the next steps are.

For the engine start, why can I not get fast idle - on start, RPM increase only, no RPM reduction, and initial unburnt fuel smell.

The ECU takes all the input signals and determines what the engine timing and required fuel is. The amount of fuel from the injectors is controlled by the ECU in that the opening duration is calculated from all the inputs. If the opening duration is too long, too much fuel will be injected into the engine cylinders, and there will not be enough air to support complete combustion. The only sensor output I can control is that of the TPS.

Rain days coming this weekend, good time to do some investigative work. Thinking I'll scope the cylinders before an engine start, make sure the cylinders are dry. Adjust the throttle plate lever stop screw - thinking that I'll change the TPS voltage output at the closed throttle position to less than what I have read. Somewhere in the 0.45 or less VDC.

The next issue I have been pondering is why is there a difference between numbers 1 and 2 cylinders and numbers 3 and 4 cylinders when I pull the plug caps. Numbers 3 and 4 cylinders have a significant impact n the engine RPM, whereas numbers 1 and 2 not to the same degree. My thoughts are that the engine should be affected the same regardless of the plug cap pulled.

With this in mind, wonder about the spark igniters and if these units get weak over time. Is it possible that the spark igniter for numbers 1 and 2 cylinder is starting to fail, only been 37 years. Ansimp from down under commented on my ECU replacement project in that I might want to consider upgrading some of the CFI components in the process. Have a line on some GL1100 spark igniters. These are 5 wire instead of the 4 wire units that are used in the CFI system. Here's the web site: pe-c-mh900-a-igniter-set-2-honda-cb650-1100-cx500-650-gl1100-as-oki-nec-mps-20
Will be studying the GL1100 wiring schematic to determine how the wiring of these units correlate with the wiring of the spark units in the CFI system.

 

[mcgovern61]

I cannot be sure with a FI engine, but on an 1100, if you see that kind of performance issue difference between 1-2 and 3-4, it is vacuum and the carbs being out of balance. Doesn't take much to be out of balance and get cold cylinders while the ones taking the load become obvious. Again, not knowing anything about FI engine, is there an item that controls intake vacuum?

 

[Rednaxs60]

I cannot be sure with a FI engine, but on an 1100, if you see that kind of performance issue difference between 1-2 and 3-4, it is vacuum and the carbs being out of balance. Doesn't take much to be out of balance and get cold cylinders while the ones taking the load become obvious. Again, not knowing anything about FI engine, is there an item that controls intake vacuum?

The FI engine balance is between the right and left cylinder banks. You cannot balance the individual cylinder banks front/rear. The FI engine has two PB (MAP) sensors - PBR (right) and PBL (left). The PB sensor for the respective side, right/left. is connected to the injector holder bodies. For PBR, it is connected to numbers 1 and 3 cylinders injector holders. For PBL, it is connected to numbers 2 and 4 cylinders injector holders.

It was mentioned on a thread I read about connecting a vacuum gauge to each cylinder on the FI engine to determine the vacuum for each cylinder. This was not to balance the cylinders, but to determine if there might be an air leak. Tried this before, but would not hurt to do it again. Honda spec allows for up to 1.6" of Hg difference between the right/left cylinder banks for cylinder balance.

It is a delicate balance. Thinking I'm being a bit too "anal" about the 1200 engine, but it keeps the grey matter engaged.

 

[OldWing SEI]

Back to top. I understood your posts as follows: The engine has very low compression. You honed the cylinders, used the old pistons, and used oversize piston rings that are not Honda. This could have worked, but it carries risks. When honing the cylinders, the bore must be accurately measured and a matching piston installed according to the measurement. The piston rings provided by the manufacturer are then installed to match the piston. If this is not perfect, you can manipulate the ignition, the sensors and the injection as you like, but without an acceptable compression, the engine runs only modestly. The basis must be right, then of course you can perfect many things.

 

[Rednaxs60]

Good evening. Thanks for the post. Had low compression and blue smoked when ever started so I rebuilt the engine in its entirety - a C-19 project. It smoked on start initially, then got worse over time. It worsened until it smoked whenever started. Cleared up after a fashion, but the blue, oily smoke on starts was annoying.

New crank and con rod bearings, new primary drive chain, new internal support bearings for alternator shaft and final drive - these were seized in place. The heads were refurbished in 2019.

The engine was completely rebuilt, machine shop did the cylinder checks, honed the cylinders, and checked the con rods for straight.

The rings that were initially used in the rebuild were from Japan and supposed to be direct replacements for the OEM rings. Took these to the machine shop to be installed on the pistons and was informed that these rings were not what was expected and the machine shop did not like them. Put the engine together with the rings and operated the bike for a very short time with these rings installed. Unfortunately the engine started to spew blue smoke on start.

Changed to a set of hasting rings, packaged under a different name. Took these Hastings rings to the machine shop for a determination, and was told they would work well. Was told what end gap to use.

The rings were 1.0 mm oversize, not Honda, and the end gaps were adjusted to approximately 0.060" for each cylinder. Should have used the 0.50 mm oversize and no end gap adjustment would have been needed. Sometime in the future may change out the rings to the 0.50 mm oversize.

The compression across the board is approximately 160 PSI, it is not low compression - the compression was south of 100 PSI before the rebuild. I know what the manual details, but this is very close to most Gold Wing engines that have been rebuilt, even without new rings.

Building a second engine. It is from an '85 Limited Edition parts bike, kilometres unknown. I call it the 1200 carcass. I have done the cylinder honing and will be using the 0.50 mm oversize rings. The standard size of these rings is 75 mm, need 75.5 mm.

The heads will not be refurbished other than new valve stem seals. The valves have been lapped as a minor cleanup. Crank and con rod bearings look extremely good for a 37 year old engine.

This engine may very well make it into the frame, and could prove to be a much better performer.

It is a balancing act and a slight misstep does not help the situation.

In the case of the installed engine, there are external issues that I want to investigate and rule out as impacting on what I am trying to rectify. A 37 year old vehicle whatever it is, has parts and components that could be on the way out. Doing the tests that I have mentioned in my other posts cannot hurt, and I'm certain I'll learn something along the way.

This bike is my long term retirement project and it will be assimilated. Resistance is futile.

 

[Rednaxs60]

Looks like the weather has turned such that it is time to do in house projects, and the tests I want to do on the 1200. Need the rain. Will be finishing trimming out the windows today, then on to the 1200.

 

[joedrum]

Lol sounds like my days ...

 

[julimike54]

You mentioned, somewhere, about the IAC feeding the air to the engine. Seems you made several checks there, but I don't remember anything about how much air is feeding into the engine, did I miss that? Only reason I bring it up is that I think you stated on cold start you smell fuel and the revs are low. If the IAC doesn't flow enough air wouldn't that make the bike run rich and slower?

 

[derrick woods]

Did you make sure ring gaps were all opposing each other 3 o'clock 6 o'clock 9 o'clock etc Not lined up?

 

[Rednaxs60]

Ring gaps were staggered IAW the manual. I have read that the rings do move - don't stay oriented where installed.

The IAC circuit uses the engine vacuum to activate the reed valves. The vacuum from the cylinder(s) draw air into the respective cylinder(s) during the intake stroke. The IAC valve is fully open when cold, and as the bimetal strip inside the valve heats up the amount of air flowing through the IAC valve is reduced. The IAC valve is never fully closed.

Having mentioned this, took the end plate off an IAC valve to look at the internals. This pic is of the IAC Valve when cold:

The orange opening is the air flow opening, not very big. I'm going to pull this valve out of my "I kept it box", and put 12 VDC to it and observe what happens to the air plate.

Read the following in the Electrical Troubleshooting Manual:

"The solid-state electronic control unit (ECU) receives information from sensors and then activates a "fuel discharge" memory from which it chooses the correct throttle opening. Additional sensors signal the ECU to help it fine tune the air-fuel mixture for all operating conditions. the ECU continuously monitors sensor signals to provide the best air-fuel mixture for the most effective combustion. The sensors monitor crankshaft RPM (Ns), air temperature (T1), throttle position ()th), manifold pressure (Pbl/Pbr), coolant temperature (Tw), piston position (Gr/Gl), and atmospheric pressure."

"The ECU controls ignition by sending signals to the spark units. The ECU uses two memories for ignition timing. One memory for small throttle openings reads manifold pressure and crankshaft speed. The second memory is used for large throttle openings. Continuous information from the coolant temp sensor, piston position (Gr/Gl) sensors, and crankshaft speed allow the ECU to advance and retard the ignition timing for specific operating conditions."

I'm thinking the "memory" being alluded to are the fuel maps that are the basis for this ECU.

I'm still of the opinion that the unburnt fuel smell is a function of the position of the throttle plate lever stop screw, and from this the amount of fuel from the injector(s). The ECU controls the injector opening duration based on input signals. At start and low RPM it uses the TPS signal to determine injector open duration.

The voltage the TPS generates increases as the throttle is opened - sounds correct. This makes the ECU increase the injector open duration. If the TPS voltage reduces, the injector open duration is decreased. On start, there is not a lot of sensor input, so my thought is that the ECU uses the TPS as a primary signal on start.

After the engine starts, there are signals, but as explained the additional sensor inputs are used to fine tune the air-fuel mixture for the best combustion.

I am going to adjust the throttle plate lever stop screw, calibrate the TPS, and look at the TPS signal to the ECU at start. Looking to reduce the TPS voltage to the ECU on start. Have it set at 0.48 VDC presently.