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Discussion Starter #1
I picked up a 1979 GW survivor, and while putting a resto-mod, found my carburetor had been trashed by a previous owner, there had only been 2. Trashed to a level that I felt they were not good candidates for a rebuild by me or a paid service.



So, I began to read up on my options. I read here, read at GoldwingDocs and NGW. I will be sharing these posts there as well, since all have contributed to my research.


Went with an eBay combo, 34 PICT3 and manifold.





I liked this one for the smooth curved shape and the claim {true} that the tool tray would still fit. I had plans for the tool try; cigarette power plug, USB charger port. Telephone installation advice and installation instruction sheet, nowhere to be found.


Still, was happy with the manifold, robust welds, nice flat mounting plate. Installation was no big deal. Followed some well written 34PICT3 tuning adjustments, and it ran. High idle speeds, stumbling in the 2K-3Krpm range. Also, the manifold runners were chilled to the point I'm sure I could ride with a canned drink rested there and stop to have a fairly cold drink.


To combat the cold manifold, I went with something new {or at least I hadnt run into it while researching}
Motorcycle grip heaters, 2 pairs.
https://smile.amazon.com/gp/product/B002OP5YDM/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1


Installation started with a layer of Gorilla tape as a bit of electrical insulation just in case they burned through. Then applied the self adhesive heaters. Wiring was done for maximum heat, each panel accessing the full 12V. Testing before installation showed very little heat generated when using any form of series wiring.I did not install the resistor for the lower temperature option.



For testing, I install a simple on/off switch. I also insulated the manifolds with this.
https://www.lowes.com/pd/Frost-King-0-125-in-Foam-Plumbing-Pipe-Wrap-Insulation/1081449

This stuff is somewhat adhesive, but not for long term, so I secured it with a plain aluminum tape.


I only insulated the manifold, and while improvements were noted, I knew I had more work to do. I did not want to be running the grip heaters at all times, and I wanted some free heat.


I solved this be redoing the insulation to include the coolant crossover tube. starting with the underside, I applied the foil/rubber insulation, trying to keep the pieces large, patching holes with smaller pieces.


Before I wrapped the top, I included a programmable 12V electronic thermostat into the mix.
https://smile.amazon.com/gp/product/B076Y5BXD9/ref=ppx_yo_dt_b_asin_title_o04_s00?ie=UTF8&psc=1

Placed the thermocouple within the dead air space of the insulation shroud, then wrapped the top and gave the whole shroud an overlay of plain aluminum foil tape.




The thermostat not only gave me a readout of the cut-off temperature, but also the actual temperature inside the insulated shroud. Initially I set the temperature to turn off the grip heaters at 120 degrees, but it was soon evident that I could cut them off sooner, as temperatures got to the 130-150 range when the bike was fully hot. Set at 95 degrees now.




Felt that some of my rough running was ignition oriented, and found I was right after installing a Dyna S ignition.


I also disconnected the electric choke. I loosened the choke adjustment ring and rotated it clockwise to allow the bimetal spring inside to close the choke when cold, and to allow a small amount of choke plate to drop at idle. Under throttle the plate opens up easily.



As it sits now, I have a bike that will idle between 1000-1100 rpm. Much of the stumbling between 2k-3Krpm is gone, and 3Krpm on up it is a stronger runner! I am done with the tweaking and will be doing mileage tests now. A check in the mid-tweak testing showed 25mpg, but there was a lot of fuel burned while the bike was on the center stand. Time for some real world mpg testing.


If I cant get the mileage where I want it, 35-40 mpg, I will probably look at a Solex 30. I suspect I will find it will be running rich, and that the 34PICT3 is simply too much carb for a 1 liter motor.


Oh, and the resto-mod?


 

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Discussion Starter #4
Here is the text, cant exactly remember where I picked it up, apologies to the author I cant credit.
Note that after I tweaked using these instructions for quite a while, after I made it the best I could as instructed, I ended up disconnecting power to the choke.
I then loosened the choke set screws to set the choke blade to where is was somewhat closed at idle using the bimetal spring inside, but able to flap fully open under opened throttle. And, during the tweaking, I did install the grip heaters, electronic thermostat and insulation including the coolant crossover tube.


I also found that the best tweaking happened with a fully hot engine. Adjustments made when semi hot didnt seem to stick by the time the engine was at full temperature.



Here is the text of the adjustment instructions.


" Turn the ignition ON and allow the Choke (Ck) to warm until fully open, then switch the ignition OFF. Do not "blip" the throttle, or otherwise work the throttle valve to excess in attempting to open the butterfly as fuel will enter the manifold unneccessarily with every blip. Give it 3-5 minutes to warm depending on ambient temperature. Alternatively, adjust the choke to a fully open position.
The first step is to set the throttle valve. Back out (counter-clockwise) the Fast Idle Adjuster Screw (6) located at the top of the throttle arm on the left side of the carburetor.
Note:"Fast Idle Adjuster Screw" is a misnomer - ***this screw it is NOT used to adjust the idle speed!***The Fast Idle Adjuster Screw (6) works with the Choke (Ck) to give a smooth idle on a cold engine and sets the the throttle valve to the correct position for the idle circuits when not in use. As the choke warms up, the choke valve in the throat of the carburetor opens and the Fast Idle Adjuster Screw (6) moves down the steps of the choke Fast Idle Cam (7) via throttle "blipping" reducing the engine idle speed and gradually closing the throttle valve at the same time. Screwing the Fast Idle Adjuster Screw (6) in more will increase the idle speed, yes, but doing so messes up the Volume Control Screw (5) and Bypass Screw (4) adjustments that control the idle mixture. ***This destroys the idle geometry***and the bike won't run right.
With the Choke (Ck) held in the fully open position (Fast Idle Cam (7) at its lowest point) place a piece of notebook paper or a 0.003" feeler gauge between the lowest step of the choke Fast Idle Cam (7) and the Fast Idle Adjuster Screw (6). Slowly turn the screw in until you feel drag on the paper or the feeler gauge. Then remove the paper or feeler gauge and turn the screw in precisely 1/2 turn - no more! This sets the throttle valve open the required 0.004", so you can use the Bypass Screw (4) to set the idle speed correctly. From this point on, leave the Fast Idle Adjuster Screw (6) alone.
Next, set the volume of gas available at idle speeds. This is done using the Volume Control Screw (5). The Volume Control Screw (5) controls the AIR volume, not the fuel volume. Screwing it in reduces the air and makes the fuel/air mixture richer. And of course turning the Volume Control Screw (5) out increases the concentration of air and makes the mixture leaner.
Note:The Volume Control Screw (5) is the smaller of the two adjusting screws, located on the left side of the carburetor just above the Idle Fuel Cut-Off Solenoid (10). The Volume Control Screw (5) is NOT used to set the idle speed - that's the job of the Bypass Screw (4).
Before setting the Volume Control Screw (5) per the step below, turn the Bypass Screw (4) in GENTLY until it bottoms out - you don't want to open the seat area up. Now unscrew it EXACTLY 2 turns.
Screw the Volume Control Screw (5) in GENTLY until it bottoms out - again, you don't want to open the seat area up. Now unscrew it EXACTLY 2-1/2 turns. These are the initial start-up settings for all engines.
Start the engine and let it warm up, making sure the automatic Choke (Ck) is fully open before proceeding. Your engine may not idle at this point if warm, so be at the ready.
Now set the idle. This is done by controlling the volume of air going by the Bypass Screw (4). Remember, the Bypass Screw (4) is LARGER than the Volume Control Screw (5).
Next, turn the idle Bypass Screw (4) whichever way (most likely out) to set the idle at 1150 rpm.
Go back to the Volume Control Screw (5) and adjust it SLOWLY to obtain the fastest (smoothest running) idle speed (this is usually out - counter-clockwise). You should not have to turn the screw much outside the range of 2-3 turns total (1/2 turn in/out from the basic 2-1/2 turn out setting).
Turn the Volume Control Screw (5) screw back IN (clockwise) SLOWLY until the engine speed drops by about 20-30 rpm (slightly leaner). If you don't have a tachometer, listen until you can hear the engine speed just start to drop, maybe as little as 1/10th of a turn on the Volume Control Screw (5). The Volume Control Screw (5) is capable of very precise metering with very small fractions of a turn.
Go back to the larger Bypass Screw (4) again to reset the idle speed to 1150 -1200rpm."
 

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Discussion Starter #5
I have a 40 and 45 idle jet coming, I would like to set up the carb with the choke at full open. I will look into installing a bellcrank to use the OE choke cable as it was designed; to crank the engine in cold conditions and open it fully when warm.


The 1150 idle is do-able, mine is about 1050.


Best thing is the stumble off idle {1100 - 2800rpm} is gone, and I get smooth power where before I had to abused the clutch with higher rpm.
 

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Discussion Starter #8
Initial mileage tests done, 29.3 mpg on 3.25 gallons, mixed driving from local street to highway speeds.
Still hope to see 35-40 mpg.



Have the Dyna S ignition and Dyna 3 ohm coils installed now.
Carb came with a 55 idle jet.
I installed a 45 jet, and rotated the choke back to full open {and disconnected power}


Noting the my temperatures inside the manifold shroud are running a bit cooler, in the 120s
 

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Discussion Starter #9
Didnt like a low rpm stumble that came with the 45 idle jet, didnt bother checking mileage.
Installed a 50 idle jet today, stumbles at low rpm slightly when cold, but smooths out after it warms up.

Mileage test this weekend, when I take off for a mini trip, Charleston SC - Cherokee NC - Blowing Rock NC - Charleston SC.

Little bit of Blue Ridge Parkway with some friends who are going the distance of the BRP and Skyline Parkway over the course of a week.
 

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Discussion Starter #10
About 1000 miles total Friday-Sunday
Trip up to Cherokee NC running about 75mph, about 31.5 mpg, until I got off the slab where it jumped to 35 mpg.
Back onto some hilly slab, dropped back to 30.5 mpg.

The trip on the BRP was at a leisurely pace, getting between 34.6 and 36.3 mpg.

The trip to Charleston SC from Blowing Rock NC, I dialed the speed back a bit. I had had to adjst the carb for altitude, and was adjusting it back on the way down. Speeds around 65 mph, got about 35 mpg.

Thinking I have a lean situation when on the main jet, difficulty hold a speed and blued mufflers.
Replace the 127.5 main jet with a 130, see how that goes.
Initial ride says gitty-up-go mode likes the 130!
 

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Discussion Starter #11
Ran a tank through with the 130 jet. Much easier to hold a given speed, and the muffler section I removed the bluing from remained clean! Forgot to reset my odo, so no mpg number. Guess I will just have to run another tank of fuel through it...!



Have a 132.5 jet on the way for testing.


Plan is that once I get the main jet size sorted, I will then have a look at the auxiliary jet {WOT circuit} if necessary after some plug chop tests. I expect to lean out the WOT a little.
 

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Discussion Starter #12
Got a few WOT jets, the one installed was a 70.
Found a nice performance increase when I went to a 60, and a bit of fall off with a 50.


Figures a 55 would have to come from Italy!
Planning on adding a phenolic spacer between the carb and manifold; getting fuel boiled into the intake when killing a fully warm motor.



Will test the 55 when it comes in, make a final decision on the main and make some final screw adjustments.
From there, I will be able to supply what is working well for me, at sea level, and with the manifold I have, and added manifold heat
 

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Discussion Starter #14
I like the challenge of the tuning. I like it better when it is almost done!
Started tuning from the idle to WOT, after this final WOT jet test/selection, I will go back down the list to get it spot on, WOT to idle.



Right now I get 32-33mpg with non-interstate travel, 1Krpm idle when warm, better starting with manual choke.




In the past I have changed carburetion on a couple bikes and tuned them in.
Went with an FCR39 pumper on my DRZ400 for more power.
Went with an ATC200X carb on my daughter's XR100 woods race bike, along with cam/ head/exhaust/CDI changes for more power.
 
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