Subject: Carb bowl fuel level theory

[Chris Cochran]

I posted this in the Voyager group on FB but it should go in here, too, for sure.

Subject: Carb bowl fuel level theory. Ok, in theory, setting the floats to the same heights (for some reason I can't remember the correct set-height of each float right now) should set the fuel levels in the bowls to the same levels. However, to verify this, there is the clear tube test where one attaches a clear tube to the drain tit and then measures the actual amount of fuel in the bowls. As I understand it, the goal of these two exercises is to ensure that each fuel bowl receives the same amount of gas. (Is this assumption correct?) So, if you have a carb that is overflowing, this indicates that the fuel level in that bowl is too high for whatever reason, and you know that you need to drop the fuel level in that specific bowl by taking whatever appropriate action. Fine, I'm good so far. But now that you know what the specific, actual fuel levels are for each bowl, how do you know WHICH carb is the one that you want to adjust the others to? When synchronizing the carbs (which is an altogether different operation) you equal-out the carbs by turning the three adjustment screws. It doesn't really matter what the syncro gauges indicate, as long as you get them all the same. But in fuel bowl levels, does this same philosophy work? Obviously, you cannot have a bowl set too high or it will overflow. But how critical is a low fuel level? Setting bowl heights gets you in the ballpark, I suppose, but other than that, do you just look at all four levels and simply pick one that seems to be middle of the road in level and adjust the others to match?

When I rebuilt my carbs, I skipped the clear tube test. I didn't have enough hands to hold everything and didn't have a stand, or method to hold the carbs for me. Now that my carbs are back in the bike, sure enough, one of them is overflowing. Lesson learned!!! I have some parts coming to me in a couple of weeks that I can use to make a work-stand to hold them securely so this next time around it will be a better job done on them.

[Nails]

No. Adjust the float bowl level to the correct height, which is clearly articulated in the manual. This is critical for proper function, especially in our CV carbs. "Synchronize" them by making them all right.

[buzzcut]

I've not done the clear tube on the voyager but did on all my other bikes. The fluid always went to the mating surface of the carb body, just like when using a float level or calipers and setting the proper height.

[Micoproviso]

Assuming the floats are set correctly, every overflowing float bowl that I've ever had was the result of a hardened or otherwise worn out rubber on the float needle (the piece that the float pushes up on to stop the flow of gas). Sometimes, they don't look bad. If you have one carb overflowing, replacing the needle would be a fairly easy and cheap thing to try. Depending on which carb, you may be able to do it with the carbs still in the bike. I did it on my Honda CB1100F, but haven't tried it on my Voyager XII yet. I replaced them all when I rebuilt the carbs after getting the bike (it sat for many years before I got it).

[Micoproviso]

Assuming the floats are set correctly, every overflowing float bowl that I've ever had was the result of a hardened or otherwise worn out rubber on the float needle (the piece that the float pushes up on to stop the flow of gas). Sometimes, they don't look bad. If you have one carb overflowing, replacing the needle would be a fairly easy and cheap thing to try. Depending on which carb, you may be able to do it with the carbs still in the bike. I did it on my Honda CB1100F, but haven't tried it on my Voyager XII yet. I replaced them all when I rebuilt the carbs after getting the bike (it sat for many years before I got it).

Also, if memory serves, I don't think the floats on the Voyager XII are adjustable. Does anyone know for sure?

[triton28]

Yes the float height is adjustable. See Chapter 2 of the service manual, pages 9 and 10.
Bending the tab of the float, which contacts the top of the rod of the float valve needle, is how it is accomplished.

[Micoproviso]

Ok, it must be my CB1100F where they’re not adjustable.

[Chris Cochran]

Recent conversation in FaceBook has been about if the angle of the carbs makes a difference when setting the floats. Some have mentioned that once they took them "off-level" then set them, that there were no further problems with fuel levels bouncing all over the place.

The Manual does not state, in text, the need to angle the carbs when setting float levels BUT the figure shown on page 2-10, DOES show the carbs at perhaps a 15 degree angle, front down hill.

To that end, has anyone in here set theirs while angled (not level)? I've been setting mine while level and the measured fuel levels bounces wildly around. It would be easy for me to modify my work stand to make this angle happen.

[Micoproviso]

Recent conversation in FaceBook has been about if the angle of the carbs makes a difference when setting the floats. Some have mentioned that once they took them "off-level" then set them, that there were no further problems with fuel levels bouncing all over the place.

The Manual does not state, in text, the need to angle the carbs when setting float levels BUT the figure shown on page 2-10, DOES show the carbs at perhaps a 15 degree angle, front down hill.

To that end, has anyone in here set theirs while angled (not level)? I've been setting mine while level and the measured fuel levels bounces wildly around. It would be easy for me to modify my work stand to make this angle happen.

Many float needles have a rubber seal at one end, and a spring loaded pin at the other end. (Not positive if voyager XII carb float needles are this type) In this case, One of the keys to setting the float height properly, is to have the needle all the way seated, but to NOT have the spring loaded pin at the other end compressed when measuring the float height. Depending on the weight of the float, on some carbs, turning the carb vertically upside down, is enough weight on the spring loaded pin to compress it. If you measure float height with it compressed, your measurement will be wrong by a significant amount. The way to avoid doing this, is to angle the carbs away from vertical enough to take enough weight off of the float needle to uncompress the springed pin. You can see visually whether it is compressed or not. Measuring float height at this angle of carb orientation will give you a correct measurement. I
I always angle the carbs with spring loaded float pins until I can visually see that they are uncompressed.

[Chris Cochran]

The Manual needs to be re-written to more intelligently address this point. There is zero written text stating to angle the carbs. Only the figure shows them angled.

Today I'm going to get out my miter saw and cut some wedges, then move my now vertically mounted carb mounts to the new horizontal (with angled wedges) one.

I don't know if I'll ever be able to tell if the hangers are compressed or not as my eyesight isn't what it used to be. I did get a nice magnifying glass so maybe that will tell the tale.

I had gotten fatally frustrated with these things but now my curiosity about this is overpowering that frustration and I want to see if it works.

[Chris Cochran]

Ok, so I made two different places to attach the carbs horizontally, one at 15 degrees and the other at 20 degrees.

Didn't matter. Yes, I could see well enough to ensure the floats juuuust sat on the valves without depressing them. But the results were still all over the place again, although not as bad. Carb#1 overflowed the first three tries I made at measuring the fuel level.

Carbs 2 & 3 actually sat on 5mm for four different measurements before #3 started overflowing. But #3 did stop overflowing yet still registered at 0mm's level.

Carb 4 started at 5 mm's then went to 0 and stayed there for three tries, went to 4 then back to 0.

I just do not understand it. One person suggested that I dump the current float valves and get some from H&L. That's $43 before taxes.

[Micoproviso]

Ok, so I made two different places to attach the carbs horizontally, one at 15 degrees and the other at 20 degrees.

Didn't matter. Yes, I could see well enough to ensure the floats juuuust sat on the valves without depressing them. But the results were still all over the place again, although not as bad. Carb#1 overflowed the first three tries I made at measuring the fuel level.

Carbs 2 & 3 actually sat on 5mm for four different measurements before #3 started overflowing. But #3 did stop overflowing yet still registered at 0mm's level.

Carb 4 started at 5 mm's then went to 0 and stayed there for three tries, went to 4 then back to 0.

I just do not understand it. One person suggested that I dump the current float valves and get some from H&L. That's $43 before taxes.

I usually use Chinese rebuild kit float needles. The Chinese carb parts can be hit/miss occasionally because their tolerances usually aren’t as tight as the OEM Japanese ones, but they are so cheap that if I get a bad one occasionally, so what. With a chronic overflow problem, replacing the float needles would be my first step. Second step would be making sure the mating surface inside the carb isn’t gummed up. I clean the carbs using a heated sonic cleaner in a solution of Master Stages Clean 2020, sometimes for hours depending on how they look, then blow out all passages with compressed air while they’re still wet from the cleaning solution. If you don’t want to get that meticulous, a q-tip dipped in spray can carb cleaner rotated into that hole over and over again until it comes out perfectly clean will do the job. In any case, measure the replacement float needles against the OEM originals with a micrometer if you have one. I’ve bought the same kit for the same carb from different sources, and they were different lengths, which can cause exactly the frustration you’re experiencing. Also, make sure the floats are good. To spot bad ones, shake them while off the carb, and you’ll hear gas sloshing around in there if they’re leaking. Sometimes, I even buy a complete Chinese carb (they’re also very inexpensive), but I’ll never use that carb. It will never run as good as the OEM carb (again, orifice tolerances, etc). BUT, most times the components, gaskets, float needles, etc are interchangeable with the OEM carb that it was cloned from. I.e. The new Chinese carb becomes a parts donor for very cheap money.

[Micoproviso]

Also, your 15-20 degrees probably isn’t enough. Closer to 80 from vertical. I’ll try to post the procedure from a Polaris manual that walks through the process.

[Bonnie and Clyde]

Something else to consider. My First hand voyager carb rebuild experience. I rebuilt my carbs 10 months ago Jan '22 and used a cheap ebay kit. Last week after our 5,700 mile trip I was having fuel run out the over fill tube when the bike was running only. So I pulled the over flow tubes off each carb bowls to identify which ones or one was leaking. Only one was leaking again only when it was running so I guessed the float needle was fine. I pulled the carbs opened that one carb and it looked fine. I measured the float height it was spot on 17mm leaning over. I pulled the float and needle. Visually I could not see any thing. I dropped the float in a bucket of water and one side of the float sunk way down. The float was not balanced and not floating balanced. No fluid in it or cracks. So I replaced it with one of the old Japanese floats that was in the bike when I bought it. Put the carbs back in and buttoned it up. Runs perfect again. Why I didn't notice it for the last ten months I don't know and possibly it was not leaking the whole time. Because it was pretty obvious when I saw it last week. So check your floats in a bucket of water to see if they float evenly.




Now on another note taking out and reinstalling these carbs is a major pain in the rectus. I would like to see pictures or a video of someone who has this procedure down pat, take out and install them. Namely the cables on and off. Cables back on is a hair pulling experience. Also the back half of the air box with boots and springs is a mess to get set correctly boots over carbs.

[Micoproviso]

[quote="Bonnie and Clyde" post_id=95094 time=1664724994 user_id=11188


Now on another note taking out and reinstalling these carbs is a major pain in the rectus. I would like to see pictures or a video of someone who has this procedure down pat, take out and install them. Namely the cables on and off. Cables back on is a hair pulling experience. Also the back half of the air box with boots and springs is a mess to get set correctly boots over carbs.
[/quote]

I’ve only removed/reinstalled on this bike 3 times, and I didn’t video it, but using lessons learned from other bikes, I removed most, if not all of the bolts holding the air box in back of the carbs (the 2nd and 3rd time performing the operation). Then used a pry bar to gently move the air box back about a half inch and secure it back there with bungee straps. That half inch made it a thousand times easier to get the carbs out and back in. The key to the cables was connecting them before putting the carbs into the front and back manifolds, so I could rotate the carbs around to get to everything. It still wasn’t easy, but the extra half inch made a big difference here also.

[Bonnie and Clyde]

[quote="Bonnie and Clyde" post_id=95094 time=1664724994 user_id=11188


Now on another note taking out and reinstalling these carbs is a major pain in the rectus. I would like to see pictures or a video of someone who has this procedure down pat, take out and install them. Namely the cables on and off. Cables back on is a hair pulling experience. Also the back half of the air box with boots and springs is a mess to get set correctly boots over carbs.

I’ve only removed/reinstalled on this bike 3 times, and I didn’t video it, but using lessons learned from other bikes, I removed most, if not all of the bolts holding the air box in back of the carbs (the 2nd and 3rd time performing the operation). Then used a pry bar to gently move the air box back about a half inch and secure it back there with bungee straps. That half inch made it a thousand times easier to get the carbs out and back in. The key to the cables was connecting them before putting the carbs into the front and back manifolds, so I could rotate the carbs around to get to everything. It still wasn’t easy, but the extra half inch made a big difference here also.
[/quote]

Thank you. So you left the rear box in place just loosed up and pulled back out of the way. Cables put on before set in manifolds so you could move the carbs around to hook the cables up.

[Micoproviso]

Thank you. So you left the rear box in place just loosed up and pulled back out of the way. Cables put on before set in manifolds so you could move the carbs around to hook the cables up.

Exactly. I didn’t remove the manifolds. I just didn’t set the carbs into them until after the cables were installed, adjusted, and tested.