More Carburetor issues!

[Midnite]

I have a 1980 XS 1100 LG Midnight Special, and I just had a friend pro? rebuild my carburetors with a brand new kit, do not recall the brand name of the kit. But in the Clymer book it says floats are to be adjusted at about 25 mm (1") for the xs E, xs F and XS SF, no information on the LG . NO WAY the floats on my carbs can be at 25 mm, no fuel would be in the bowls at all. He set it at 19 mm (3/4 ") but I do have some idle problems now, my bike idles OK for a while, then revs up to 3000 RPM, back down, and sometimes dies on the way down the RPM scale. The carburetors was rebuildt with all new needles and stuff, but has not yet been syncronized? Any ideas or help will be greatly appreciated. Is the carburetors on a LG different then on a regular XS?

[rover]

Look under tech tips in the left margin of this page. It will tell you how to set the floats on the later G and H models, using the hose and level procedure.

[skids]

Look in the back of the Clymers for the float settings. You do not have to use the manometer (U-tube) method. You are right. 25mm is too much distance. Sorry, I do not have my book available. The carbs for the 80's and the 81's are the same. BTW.

[pgg]

Midnite, 23mm above gasket surface for a LG. From the manual.

[nashville_bill]

With that much of a change of idle speed, you might want to check out your intake manifolds to make sure you don't have a vacuum leak.

[Midnite]

Thanx, and more?

Thanx for your answers guys, I must you guys are a helpful bunch. The idle travel is gone now, after I adjusted the idle mixture screws to 1 1/2 turn off the bottom. But it must be running very, very rich, there are soot coming out at the end of the exhaust pipes, and the spark plugs are BLACK with soot. To make it leaner do I turn the idle mixture screws in, or out? Also could the float setting at 19 mm and not 23 mm cause this? I am sorry for all the questions, but I do not know one thing about carburetors, thanx guys.

[ratbyk]

Carb Problems

Midnite, leave the idle mixture screws where they are at present
Pull the carbs (again) remove float bowls. Turn carbs over (upside down. Your float setting is from the float bowl gasket on the main body to the bottom (now the top) of the floats. You are striving for 23 mm but in fact we have found that 25 mm is even better on these old bikes/carbs.
Before putting the float bowls back on/while the carbs are still inverted. Try blowing (mouth pressure) into the fuel lines. First the line between carbs 1&2 then the line between carbs 3-4. The weight of the floats should seal the needle and seat. You should not be able to move any air. (this is just another possibility on your rich mixture that we are checking)
After reassembly and mounting warm the engines up well before touching the idle mixture screws. Once fully warmed up turn one in slowly until that cylinder starts to fault-er. Now turn it out until again the engine starts to change in sound/feel. Split the difference between in and out then move onto the next carb. Work your wat across. Without a color tune or vacuum gauge this is how I set my idle mixture.
Once your done you are going to know a lot more about carbs than you ever thought possible. Besides learning, it is fun to make old equipment operate properly.
Have fun (I hope)
Ken/Sooke
78E Ratbyk
82 FT500 "lilRat"

[Midnite]

Point Zero!

Thanx Ken, I will do so. I had my mind 1/2 way made up to start over anyway. BUT for the 19 - 23 - 25 millimeters, I find different ways to measure on different threads in this forum. From TOP of the gasket to top of float, or without gasket to the top of float? The gaskets I pulled of my carburetor is 1.6 millimeter thick, so there is a difference, maybe even 2 millimeters as a fresh non compressed gasket? But I also read in the post that the VERY MOST important thing is to have all floats even!

[skids]

Re: Point Zero!

Take the gasket off and measure from the metal mating surface of the carb body to the flat areas of the floats. Measure one bulb, then the other, and use the average. At least that is what I do.

Originally posted by Midnite
Thanx Ken, I will do so. I had my mind 1/2 way made up to start over anyway. BUT for the 19 - 23 - 25 millimeters, I find different ways to measure on different threads in this forum. From TOP of the gasket to top of float, or without gasket to the top of float? The gaskets I pulled of my carburetor is 1.6 millimeter thick, so there is a difference, maybe even 2 millimeters as a fresh non compressed gasket? But I also read in the post that the VERY MOST important thing is to have all floats even!

[Midnite]

Also I am made aware from people outside of here that the Midnight has different carbs than the regular, and the settings are different? Any truth in that? I have a Clymer manual, it lists the 78 - 81 E, SF, SG, SH, F, G, H, but not the LG? That manual tells me 25 mm on the float height as well, but my model is not listed in the carburetor section, my man that set the floats on my carbs still hangs on to the 19mm, he says 25 mm will not feed the engine with fuel?

[ratbyk]

Carb Problems

Midnite, you have seen how rich your engine is running with the float height at 19mm. Black exhaust and black sooty plugs is away too rich. Lean it out by lowering the float level. No offense to the expert that is helping you but the book says 25mm, my experience says 25mm and most of the people on this Forum are at 25mm or very close to it. The only reason to go higher or lower would be to compensate for having jets that were not quite right on for your bikes exhaust/air intake.
Running rich, lower the float level.
Running lean, raise the float level.
Many times it only takes a mm or two. But that is staring from 25mm not 19mm.
Ken/Sooke

[pgg]

XS1100G,SG,LG - 23mm +/- 0.5mm above gasket surface.

XS1100E,F,SF - 25.7mm +/- 0.5mm above gasket surface.

XS1100H,SH,LH - 3mm +/- 1mm below top surface of float bowl.

From 80-81 service information (supplemented)

[wiredgeorge]

FWIW, The center of the tang on the float (the metal square over the float needle) is what SHOULD be bent to adjust the float height. Over time, folks bend the tang that holds the float as well as the center of the tang. Eventually, the whole thing gets bent up to the point where the float level adjustment becomes somewhat unreliable. When I adjust the amount of fuel in a float bowl, I do it "wet". I put the carbs in a holder and fill them using an auxiliary tank and measure how much fuel is actually in the bowl by connecting a hose to the bowl bottom and holding the hose next to the bowl. Generally, the gas should be about 1/8" below the juncture of the bowl and carburetor body... in other words at the line where the gasket is. Too much gas will cause the carbs to drool, no matter how good the seat between needle and float seat and it can also come out the vents which are connected internally to the area above the bowl. Too little gas will cause fuel starvation... you will run out of gas literally. This is why I adjust fuel level using the "service fuel level" for ALL carbs I work with.

[Midnite]

OK, here is an update on my carb troubles listed here and in another thread: HERE

I got new original Mikuni main jets today, I did get them installed, double checked the float height, the floats are dead on at 23mm above gasket surface, wich would be about 24.6mm above surface without gaskets. I also reset the idle mixture screws again from 1 1/2 turn out to 1 1/4 turn. I got the carbs back on the bike, and that is as far as I got today. Limited time after work, it gets dark pretty early still. Besides it was colder than @$#$#% here today.
The plans for this week is to install the new fuel lines, I got some red ones that I think will look pretty hot in contrast to the black engine on my Midnight Special. Also inline filters is getting mounted. I did sync the carbs before I took them off last time, do I need to sync again after the octopus removal and re-jetting? Should be OK still huh?
OK, I will keep you posted, and hopefully my Big Black cat will be purring this weekend, begging me to take her around the block at least

[skids]

There should be no change as long as you left them attached to the bracket, did not turn the synch screws, and the boots were not leaking before or after... Jetting does not change synch.

Originally posted by Midnite
I need to sync again after the octopus removal and re-jetting? Should be OK still huh?