GL1000 tuning with an AFR gauge

[NightSkiesP]

Hi,

Attempting to install an AFR gauge on my 79 goldwing, but this specifies that I need to be at least 18 inches downstream from the exhaust port. The 2-to-1 headers on the goldwing are too short for that. Is the 18 inches critical? Can it be alot closer? (12 inches?). Will I ruin the O2 sensor? If there's a better (not too expensive) AFR gauge I'll buy one.

Thanks!

N.S.





Background: I've posted before about this bike in general before, but I need help with a specific attempt to fix it.
I have a 79 GL1000 with MPG issues (7-10 MPG, drastically lower than the expected 20-40 MPG). It has signs of running too lean, and I believe the root cause is improper jetting. The bike has a '76 carb bank and I rebuilt and cleaned it a few times with the 75-79 standard carb rebuild kit including jets.

[robin1731]

So you bought a rebuild kit that has jets? And you used those jets? If so take those out and throw them as far as you can. Then install the original stock jets back in to the carbs. Needles too if you changed those. Aftermarket jets and needles are terrible. I had a customer bring an early wing for me to "fix" for him after he rebuilt the carbs. It had aftermarket needles in it. I had to replace those with the correct needles to get it to run right. He also did not split the carbs from the plenum or split the plenum. Which means he didn't do a correct rebuild. It would have been cheaper for him to just bring me the carbs for a rebuild to begin with.

the first thing you should do is pull the carbs and replace all the aftermarket brass with the original parts. If you have 76 carbs rebuild them as 76 carbs.

[redglbx]

What Robin said ! That cheap Chinese crap is just a waste of time & money. Maybe contact Robin about doing a proper rebuild for you. By the way, with the fuel economy you are having it’s gotta be waaaay rich not lean.

[Rednaxs60]

An AFR gauge is a great engine performance tool. Installing a new aftermarket ECU on my '85 1200 FI model, and have had to install a WBO2 sensor. Not a lot of space for the install, but have it installed near the after end of the engine. This spot works well:

45198-Exhaust-Header-.JPG (67.33 KiB) Viewed 305 times

O2 Sensor Installed.JPG (108.05 KiB) Viewed 305 times

In your case, a NBO2 sensor should be good. It will give you an indication of what the engine is doing on the side installed - is there a cross over pipe?

Why an O2 sensor. Good for looking at. If you converted to EFI or ignition based timing (leave fuel alone) it may be of use. You have no way of knowing what the engine RPM and load combination is for any O2 reading. Reading the spark plugs to balance and do a good calibration of the carbs may be a better option, and it's free - just takes time and some plugs to use.

The other tuning tool you can use is reading spark plugs. Very informative, been around a long time and is still used as a "tool" for EFI systems. Video for you viewing: https://www.youtube.com/watch?v=yvTeyNM_BwY&t=991s
Article on plugs: https://honda-tech.com/forums/forced-in ... A-3063102/

Plugs can indicate what the ignition timing is, air-fuel mixture, and heat range. Everything is a guide.

Good luck.

[gltriker]

snip-
The other tuning tool you can use is reading spark plugs. Very informative, been around a long time and is still used as a "tool" for EFI systems. Video for you viewing: https://www.youtube.com/watch?v=yvTeyNM_BwY&t=991s

Article on plugs: https://honda-tech.com/forums/forced-in ... A-3063102/

Plugs can indicate what the ignition timing is, air-fuel mixture, and heat range. Everything is a guide.

Good luck.

That comprehensive Article on * reading * spark plugs is Excellent information!!

[redglbx]

Once upon a time I was considering mounting a a/f ratio system in my 76 and figured I would mount the oxy sensor in the crossover part of the muffler which should be a good spot. BUT I just couldn’t bring myself to mess with the ceramic coating I had done to the muffler, so I ended up just using my old Sun machines a/f ratio gage which correlated pretty well with the Lamda sensor on the dyno I got to use, so I just didn’t do the a/f ratio meter.

It is a great tuning tool but I’ll add that I got to see a lot of Keihin carb equipped bikes ran on the same dyno and no matter what the engine attached to the said Keihin equipped bikes were the a/f ratio’s were pretty close to the same.

[Rednaxs60]

The O2 sensor is great. The O2 sensor should be disabled during initial engine tuning so as not to influence the VE table calibration. The O2 sensor will still indicate the AFR/lambda readings. The AFR table is populated from a well calibrated VE and spark (ignition) timing table. Tuning an engine, once all components are installed, initial timing - generally set at idle timing (before initial start) is done - set trigger angle. Once engine started, and have a smooth well tuned base idle - VE and spark tables calibrated for lowest MAP reading. Spark Table can be a wedge table to get started, on to road trials.

Calibrate the VE table first to get best engine performance using lowest MAP reading for the engine RPM/load cells being targeted. Once the VE table is as good as possible for this part of the engine tune, calibrate spark table. Will have to visit VE table again. Repeat VE and spark table calibration until you have the lowest MAP value for the various areas targeted. Use the calibrated VE and spark tables to determine the AFR table values.

Once the AFR table is populated, enable the O2 sensor. This disables the VE table and the ECU uses the AFR table for the fuelling calculations. The AFR table will always try to bring the engine back to the AFR table cell value, unlike the VE table.

There are other settings that influence the engine tune, but that's for another day.

Good luck.

[Rednaxs60]

Looking into an ignition only ECU project on Classic GW forum. The reason for this is the ICU for the 1200 carb models is scarce if you need one. It would be good to have an alternative, or the bike is a candidate for a lawn ornament. Keep the carbs, tune engine so that you get the best air-fuel mixture using "reading the plugs" as a guide. Use a Speeduino NO2C (very small footprint) for this piggyback ignition system. No affiliation with Speeduino other than I like its product(s) and using it on my '85 1200 GW FI model. The '85/'86 1200 FI models have the same issue, if the ECU fails, OEM ECUs are scarce, the bike is a lawn ornament. Be able to use an O2 sensor for engine tuning if you did this. Use a MAP sensor and you would be able to determine AFRs at various engine RPM/load combinations. You would not be able to use an AFR table to determine fuelling because of carbs, but you would be able to tune the engine for best performance.

Being able to use tuning software such as Tuner Studio and MegaLogViewer to tune the engine is very nice - lots of features to play with (not always a good thing). Not a bad idea to install an O2 sensor, but need the amenities to use it to your advantage.

I look at the plugs after each road trial and find that the "reading the plug" article is fairly accurate. The timing indication on the ground strap is vey noticeable, and the description of the air/fuel mixture ring is on the mark. The fuel ring description on the plug porcelain is spot on, but don't want to destroy too many plugs to keep a running tab.

Possibilities and options are always available.

Good luck to all.

[Rat]

Whew …

Gord

[NightSkiesP]

Thanks for all the replies. I'm not doing performance tuning really, I'm just trying to get the miles per gallon MPG within reasonable range.
In the past the plugs have looked fairly normal. One of them was white though, indicating possible head gasket issues, but the head gasket has now been replaced. I don't know what that one's gonna look like now.

I'll definitely try and get proper needles and jets, or perhaps just reinstall the old ones.

If I go forward with the O2 sensor way, anyone still have any clue on how close to mount the O2 sensors? I need to be able to monitor each cylinder, so mounting them after the pipes join would be bad. I've read at least once that you can ruin the sensor with too much exhaust heat. I believe my current one is a wideband sensor. Not sure.

[Rednaxs60]

MPG is a good goal. Air-fuel mixture, can't do anything about the air, or the timing. Fuel is jetting and fuel bowl float settings, and sync of carbs. As I mentioned about reading plugs, this will be your best engine tuning indicator. It does work.

O2 sensor install location is not that critical for what we need. Find a spot on the exhaust header where it can be installed such as where I indicate in one of my previous posts. Install a MAP sensor as well. Put the gauges close together and keep tabs on the readings. You can now keep a log of the readings and compare engine load (MAP sensor), RPM and AFR. Pick a set of parameters based on engine RPM. For example, at 3000 RPM (keep a consistent speed) you notice the MAP reading at 60kPa and an AFR of 13.0. Engine is operating on the rich fuel side. Do this for various engine RPM and keep notes. If the average AFR is on the rich fuelling side, and the plugs indicate the same, need to change the jets to a lower value.

OEM fuelling will probably be on the rich side, protects the engine from us. Good luck.

[Track T 2411]

Lots of wonderful and educational reading above and I'm not poo pooing it, but in my humble opinion, apply the KISS method starting with Robin's advice above. The simplicity of SSBB (suck, squeeze, bang, blow) leaves few reasons for such grossly poor MPG.
Suck: Yes, carbs seem complicated, but the foundation of their function is over a century old. It works and is easily diagnosed, no computer needed. A clean air filter and unobstructed air flow is important too.
Squeeze: Compression is obviously important. Make certain the valves are adjusted correctly as well as the cam timing.
Bang: Spark is good. Good spark at the right time is better. People much more experienced than I will tell you 'carb issues' are often actually ignition issues. Failed resistor caps, old/bad plug wires (and connections), faulty coils, and failed/ faulty advance mechanisms, or any combination of said can cause the carbs to try and compensate. It has even been noted that some engines may have incorrectly degreed timing marks on the crank.
Blow: One thing these engines seem tolerate well is exhaust changes, except when flow is compromised. I've read of several instances where the inner wall of the 1000's header pipe partially collapsed, causing significant issues. I will add that red squirrels and chipmunks seem to love hiding their winter caches in exhaust pipes, lol!

Phew! All that said, I have had only one engine performance issue I never figured out. After going through all the above several times and narrowing it down to one cylinder, replacing the one carb body fixed it. No clue why!