Which way is up?

[rman]

My plugs are always black. I am also concerned that I am getting about 24MPG as well.

Since I had to remove the fuel tank today to fix a leak I decided to clean the carbs as well. With the carbs off I thought I would try to compensate for the black plugs (Rich condition?) by adjusting the floats. I found the floats set at 25.4mm and lowered them (lowered as it sits upside down on the bench) to 24mm. This seemed to help as after a short ride around the block (5 miles) the plugs were clean on my return.

I was reading many posts today on adjusting the carbs and was rather confused over what effect lowering or raising the floats will have? I thought that by dropping the floats from 25 to 24 that I made the mixture more lean. (Less fuel? to air) and that raising the floats say from 25 to 26 would add more fuel to the mixture making it rich.

Current jets are
137.5 main
45 Pilot
210 Air pilot?

So is my head screwed on right? Floats up rich, floats down lean?

[John]

By 'raising' the float level to, say 25mm from 23mm, you actually lowering the fuel level in the bowl. The higher the number, the lower the fuel level. Make sense?

[tw1980]

By decreasing the float level you have increased the amount of fuel in the bowl.My guess is that should make it a little richer when you nail the throttle.If your bike is to rich at cruising speed I would be more interested in the pilot circuit and the needle settings.See tech tips. Terry

[rman]

By 'raising' the float level to, say 25mm from 23mm, you actually lowering the fuel level in the bowl. The higher the number, the lower the fuel level. Make sense?

Ok, so I am wrong that dropping the floats makes the mixture more lean. I can not argue however with the limited results that I have seen on my short ride last night. The plugs were clear after my ride not black. Any ideas as to why? At this point I am guessing I just stumbled blindly inot a sweet spot.

[thewiz]

Well ...

you cleaned and adjusted the carbs during the process of re setting the floats, right? That likely took care of the problem Good work.

[randy]

Ray, you wrote that you had the carbs upside-down and changed the height from 25.4 to 24mm. That would raise them in the installed position, making the mixture richer.

It's possible that 25.4 was too lean and you were using more throttle than necessary, running on the main jets at low rpm's. That may explain the blackened plugs. Is the thottle response better?

IIRC, like over a year ago, we set your floats to stock specs, then you installed the harley mufflers later. No adjustments were made after the muffler change?

[rman]

Randy,
That is correct, after I had installed the harley mufflers I had not made any adjustments. Opps, no wait I did drill two 1/2 inch holes in the airbox trying to improve performance.

I kind of figured that I needed to resync the carbs but had not yet acquired a sync tool yet. I think you may be onto something as when I rode the bike last night it was running like a raped ape. Damn near lost both my arms when I was cruising at 50MPH and went WOT to pass a car. Definitely more pep in the old girl now.

[randy]

Yeah, figured you were using more throttle to make up for the lean condition, which opens up the mains net result being too much fuel too soon. It will also help to run the motor at or above 4K rpm, that seems to be the sweet spot for mine. Keep it in the low rpms and it will not give you very good mileage. The cams don't wake up until 3500 rpm and the motor starts to breath well after that.