Anatomy of the Carbs

[jetmechmarty]

Thanks Greg. I'll do that.

[BA80]

Just take one of the bowl plugs down to the hardware store and find fittings that'll fit. There's nothing special about the size or thread.

[jetmechmarty]

Yes George, I remember that. My bike got to runnin' well since then. Thing is, it went from scary lean, to rich. I get 25-30 mph, maybe 32 if I'm crawling along. I want to check the float heights with the engine running. The plastic tubes with electrical tape wrapped around the ends might leak more than I'm comfortable with. My bike has been on fire once before and I don't care to do it again.

[GLoweVA]

What are y'all using for a bottom of the bowl fitting for the clear tubing? 1980 bowls.

Here's. A thread from a few years ago.

http://www.xs11.com/forum/showthread.php?t=36599

[jetmechmarty]

What are y'all using for a bottom of the bowl fitting for the clear tubing? 1980 bowls.

[3Phase]

I think some of that smog blew over from LA and that's the air that diesel had a runaway on.

Coffee! Well, it was too lean anyway; needed to lower the fuel level in that cup. <laughing and shaking off the keyboard>

Back in the '60s and '70s we had SMOG out here that'd easily run an air-fueled engine but we just don't get the good stuff like that any more!

.

[mack]

Levels

This all started with a how to on doing the hose method. The issue became, "what is the correct level" to set them at. 78/79 carbs only had the 25.7 mm =/- 1mm for brass, then Haynes says that if you use plastic floats on the older carbs, the measurement was 23mm +/- 0.5 mm. I've dertermined the reason for the 0.5mm difference was due to the float hitting the tunnel and bottoming out. This is easily remedied with a chainsaw file on the tapered portion of the float body.
Then of course in 80 the carbs changed again and that same tunnel comes up at a slightly shallower angle so the full 23.5 +/- 1 mm has been restored.
Still the reference to the 3mm +/-1mm from the lower edge of the mixing chamber left a fudge factor of 2, 3 &4 mm. This is what I've been testing to determine if the narrative or the diagram is correct.
I had twenty plastic floats here plus what was in the carbs already. In all those floats, I only had three that hit the same fuel level when set at 23.5mm.
After talking with Scott I realized that my testing was done wrong. I'd been adjusting the levels on multiple carbs and exchanging them on both bikes.
Then I fractured my right hand and can't use my fingers too well. So after the surgery I plan on redoing the tests using only one carb per bike, and cycle the floats through each set. This will determine if the difference is in the float or in the fuel needle pin tensions.
Biggest problem is we are running out of riding season up here fast. Summers aren't what they used to be. Anyway it's not important what the culprit was ,the levels were set and the carbs tested. In the testing I did, 2mm ran rich, 3mm had great performance and were still just a bit rich, and 4mm corresponds to the diagram for the 80/81 carbs and showed no carbon on the plug ring at all, but the performance was not as sharp as at 3mm.
Since most of the people owning XS 11 are usually on a strict budget and try to keep these bad boys running using the old scavenge where possible, baling wire and duct tape. It's probable that reusing and mixing fuel needles and seats will occur. When that happens the hose method will be the only accurate way to set the floats. Will the bike run without doing this. Sure, but thats a testament to how durable the design of the bike is. They will run under the most unlikely conditions. Many have got there riders home on only two cyclinders. Thats why I love them.

[motoman]

T.C.,
I had analy set the floats@ .905(23mm) when I last went thru the carbs just a few days prior to the CanonCity rally just to make sure Scott and I had got ALL the 'science project' out of EVERYTHING. With the funky rich issue goin' on no matter where the rpms were run at, bout a week after the rally having it just sitting there sneering at me, I decided to just 'hose' all four carbs just for grins more than anything, expecting to find those fuel levels to high, specially just sittin' there not running.
Flipping the petcocks to PRIME so fuel would replenish what was robbed in the hose, to my surprise the levels were identical across all four......9mm down from upper carb casting...WTF! . Now, true enough it wasn't running, but I would of expected the opposite, specially not running .
So, just to confirm that level to be at least close to that initial 'just for grins' check, I'll do it again RUNNING when I get back home next week. Who knows, I may get another surprise, but just can't hardly believe they would come up much if any to be anywhere close to at least the 6mm needed to be correct with it in running mode.
Anyway, I'll post here what those running levels are, and we'll figure out the rest from there on the carb issue thread I had already previously started .

[BA80]

Hey Greg,

I think the term you're looking for is OXYMORON.

Brant, Gred, aside from a FLOW BENCH, Mack has been doing a lot of actual real world testing with various fuel levels....measured with the tubing while running, comparing both performance and plug appearance at the 2, 3, 4 mm marks from bowl surface. I'm sure "we" would convince him to perform the same test setting the carbs fuel levels much lower...ie. 6 or more mm's! How LOW would you say would be needed for this test Brant??? He's still collecting data from the various tests before publishing his results... so perhaps he can wait until he performs this extreme low fuel level = rich plugs test results!?

What say you Mack...are you up for it...once your hand heals and you can turn a wrench again??

T.C.

Oh great, now I have a NEW name. Kinda like Bne.

[TopCatGr58]

Hey Greg,

I think the term you're looking for is OXYMORON.

Brant, Gred, aside from a FLOW BENCH, Mack has been doing a lot of actual real world testing with various fuel levels....measured with the tubing while running, comparing both performance and plug appearance at the 2, 3, 4 mm marks from bowl surface. I'm sure "we" would convince him to perform the same test setting the carbs fuel levels much lower...ie. 6 or more mm's! How LOW would you say would be needed for this test Brant??? He's still collecting data from the various tests before publishing his results... so perhaps he can wait until he performs this extreme low fuel level = rich plugs test results!?

What say you Mack...are you up for it...once your hand heals and you can turn a wrench again??

T.C.

[BA80]

Possible(your least favorite reference).....stranger things have happened in Bizarro land .

No, my least favorite reference is " definite possibility", a contradiction in terms

[motoman]

Possible(your least favorite reference).....stranger things have happened in Bizarro land .

[BA80]

I think some of that smog blew over from LA and that's the air that diesel had a runaway on.

[motoman]

......and I thought Colo. had the market captured with the best 'smoke' .

[BA80]

I would but I'm busy here dodging flying monkeys. They came right after all the Kenworths on the highway zoomed through here at 120MPH out of control. I'm hiding underground before the Macks and Freightliners show up.

What was REALLY scary is when a bunch of old carbureted bikes went by with flames shooting out the exhaust because the float levels were too low and there was unburnt gas spewing out the tail pipes.

Where the hell is Superman when you need him?