My Carburetor Tuning Experience

[mountaineerxii]

So I completely rebuilt a '97 XII with 26K on the clock this past year, full carb rebuild was part of the work scope.

Using the service manual directions, I set the float levels as exactly as I could, then verified the wet level in all the float bowls to all be exactly the same as I could, though #2 carb seemed a bit flaky with it's level (NOTE TO SELF: always listen to the little alarm bells going off in your head) . At engine break-in, I tuned the carb pilot screws using the RPM-method outlined in this forum's Tech-Section (gets you close). I calibrated the carbs using vacuum gages (these were junk), and set the RPM using a laser tach, all in several iterations, dialing it closer each time.

Bike ran well for about 2,000miles, then at low rpm got as course as a cob and started stinking rich. Thru several evenings, I figured out there was no way to tune this out. Pulling the plugs revealed #2 plug was as black as coal; a bad carburetor float valve; dang after-market parts.....

A 2nd "new" carb kit and a week later, I'm back to tuning again, except this time all the tuning settings are really dialing things in, and THIS time, I have better tuning tools, giving me more accuracy.

Here's what I did and the tools I used:
Carburetor float level (when body held @ 45deg) = 20mm (factory 17mm ended up too high on wet test)
Wet test = fuel level at float bowl seam, per factory
Pilot screws = 2-3/4 turns (set using a Gunsen ColorTUNE, my nose, & my ear)
2 turns factory setting = bike barely runs, lighter blue flame on ColorTUNE, zero rich smell
3-1/4 turns = super smooth idle, obviously yellowing rich flame on ColorTUNE, super stinky rich smell
3 turns = smooth idle, blue flame on ColorTUNE w/occasional twinges of yellow, stinky rich smell
2-3/4 turns = hint of coarseness at idle, solid dark-blue flame on ColorTUNE, and no stinky smell
Carb sync performed with a Morgan Carb Tune & set to factory tolerance
Engine idle set to 825rpm per factory spec using laser tach & reflective tape on flywheel

Bike again runs great, 48-52mpg depending on where/how fast I'm riding & whether 2 up or not.

There was a lot of change between 2-3/4 turns and 3 turns with really no sweet spot in between. I blame using after-market pilot screws. I suspect factory screws would fix that, but not important enough for me to care at this point.

The Gunsen ColorTUNE and the Morgan Carb Tune were the bomb!!!

[Mr Jensee]

Sir your best bet would to ship your carbs to Carl Leo where he can exchange them for a set that is preset and tuned. He lives near Daytona Beach Florida. You can contact him by emailing him at Voyagerparts@bellsouth.net.

[dsmmrm]

Seems to me if he's got it running great there is no need to send the carbs to Carl. Maybe a finer tweak? In any case, thanks for the info.

[cushman eagle]

That was quite interesting reading of your carb tuning experience.

[ekap1200]

That was quite interesting reading of your carb tuning experience.

That it was Loren... I owned one ( Color tune ) ages ago for use on single cyl's. dirt bikes . And I do mean ages ago.. Don't quite know where it went. I would not want to own just one and keep changing it out on a 4 cyl engine. But I want to know why a rebuild at only 26K on a Voyager ? And I believe Carl has mentioned not to use the float valve spring clip , that holds , the float to needle valve. Use the old OEM one when using those kit's. Matt , what led up to the carbs needing such a service so soon ?
Were there ( heavy floats ) and or corrosion on the brass parts ? Bad float/valve ? You could always reuse the original pilot screws at the original setting they were at.
Keep us informed, you have me curious as to what happened to this at 26K as I just can't understand why some machines can go over 100,000 with never needing the carbs removed.
Gene K.

[cushman eagle]

That was quite interesting reading of your carb tuning experience.

That it was Loren... I owned one ( Color tune ) ages ago for use on single cyl's. dirt bikes . And I do mean ages ago.. Don't quite know where it went. I would not want to own just one and keep changing it out on a 4 cyl engine. But I want to know why a rebuild at only 26K on a Voyager ? And I believe Carl has mentioned not to use the float valve spring clip , that holds , the float to needle valve. Use the old OEM one when using those kit's. Matt , what led up to the carbs needing such a service so soon ?
Were there ( heavy floats ) and or corrosion on the brass parts ? Bad float/valve ? You could always reuse the original pilot screws at the original setting they were at.
Keep us informed, you have me curious as to what happened to this at 26K as I just can't understand why some machines can go over 100,000 with never needing the carbs removed.
Gene K.

I agree, Gene ,with the question of why you would want to rebuild the engine at only 26,000 miles I was wondering that when I first read it.

[mountaineerxii]

When I bought the bike it was a 20yr old basket case, just a little bit better than a barn find, had been sitting for years, would barely run. Leaking gas, coolant and oil in more places than a guy could count. And as a bonus prize, the battery had leaked and ruined most of the paint down the back of the motor, frame, etc.

As for the carbs, it was obvious they had been into previously by someone who, let's just say needed a tutor. They were dirty, sticky, and leaking gas. Lucked out that the floats were still good and nothing corroded on the inside, just dirty.

As for the bike, I completely disassembled it, removed the engine, completely rebuilt the top end, piston rings, valves, etc. There was some mild cylinder wall scoring where the engine had sat for so long, but was able to hone that out fairly easily without appreciably affecting the bore diameter.

Rebuilt the front end, the suspension, the rear end, drive train, etc. The only serious thing I didn't do was crack the main transmission case apart. There were some rubber parts & seals down inside I wanted to replace; but time, money and commitment got the best of me there. Splitting the case requires a guy to take out about 25 bolts that have had 20 years to naturally seize themselves into aluminum castings. Breaking any off could spell certain doom, so considering the low mileage and the fact I couldn't tell anything was necessarily wrong, I crossed my fingers and left that alone.

Almost completely new paint job on everything, just about all-new rubber parts, bearings, seals, etc. everywhere. Obviously things like tires, brakes, hoses, calipers etc. all had to be redone and rebuilt as everything was seized up. Lot's of aftermarket bits and farkle based on the good guys on this forum's experiences.

Mechanically speaking, the carbs were some of the easier, less technical, work I did. The nice thing was with the low mileage, most everything important made of metal was only barely worn, so a lot of time on disassembly, cleaning, polishing and re-lubricating (check out my funny speedometer posting).

Bike looks nothing like it did when I got it. Spent about a year, and way more money than it's worth, but now I have a very nice, (hopefully) reliable, low-mileage bike that was still way less than half the price of a new Voyager 1700, and still about half the price of what I could have bought a similar vintage/mileage Goldwing or HD for. So I guess that's something. Mostly I just had fun with the project.

Really like the bike so far, it's running fantastic to date (outside of the little snafu with the #2 carb posted above). Two or three more weekend trips and I'll be fully confident in it's reliability to go out of state with it.

Everyone one has hobbies, mine is rebuilding bikes. The wife says in the long run it's cheaper and way better for my health, for me to be out in the garage by myself spending money on bike projects, than running around town spending money on other women. She's probably right!

Have Fun!

P.S.: This winter's project is to pull the engine out of a Buell and rebuild the top end in it, as it mysteriously blew a head gasket when pulling it into the garage the last time I rode it. But hey, it's a Buell, I shouldn't expect much more than that!

[ekap1200]

OK, that clears things up. It's the love of the challenge and restoration, I can remember those days when I could not get enough repair work. Sometimes coming home from work as a mechanic only to find someone at my house needing something done to something.
Now , well not so much. I look for the best way to get things done without spending allot of cash or time. Engine's can be found less expensive than a rebuild, bikes with less broken / worn or dis-colored parts can be found online , and me with more time to enjoy what little time I may have left. It is a rewarding thrill to bring a bike back from age or neglect if you have the time, money , to do it.
That said, your on the right forum, as we all know a thing or two because we've seen a thing or two. ( sounds like the Farmers Ins commercial , don't it )......
If you can't find a fuel pump I may have a used one here off a running machine.
And when you get it all done and things are all working show it off and post some pics
Gene Kap.

[gtem]

Just wanted to say thanks for this writeup. Currently going through the carbs on my new-to-me XII, replaced float valve needles but still seeing wetness in the pilot air jets, I suspect that I likewise need to raise the float level some beyond that recommended 17mm spec.