Float Level question

[Anonymous]

I know the floats are supposed to be set to 22mm. (1981 GS850GL)

If they are set to 24mm does that mean the engine gets too much fuel? Or too little? Or does it work the opposite way?

I've been working on the bike all day and am to the point I need to balance the carbs. My idle is way out of wack and seems to vary directly with the amount of fuel I have flowing from my fuel source. (I found a funnel with a valve at the bottom. )

When I fired the bike up initially it idled at about 1000 rpm, which I thought was pretty good. I left fuel flowing and cleaned up an area to sit in. When I cranked the bike up again, the idle shot way up -- to 3500. I shut the funnel off and the bike eventually dropped to 1000 or so.

I repeated this process a couple of times. The idle peaks and maintains 5000 for a short period of time.

I've got the carbs off and am resetting the floats. They may have been set more toward 24 than 22. As I was doing the adjustment I started to wonder if a setting of 24 would even cause my problem.

Am I grabbing at the wrong straw here?

As always, thanks for all the help.

[SqDancerLynn1]

Since you measure from the gasket surface to the top of the float with the carbs inverted. when the carbs are turned right side up the float would not raise as high before the float would shut the fuel off. Adjusting to a higher # Translates to a lower float level

[Anonymous]

So adjusting to a lower number would allow more fuel to flow into the bowl before it is cut off.

And therefore, the float ajdustment is not my problem. Correct?

[earlfor]

Re: Float Level question

Setting the float level to 22 mm would mean the lower surface of the float would be 22 mm from the bowl gasket surface on the carb when the float needle was pushed close. Setting the level to 24 mm would mean the fuel level in the float bowl would be lower when the float pushed the float needle closed Lowering or raising the float level does make a difference relative to the mixtures being lean or rich, but its very unlikely that a 2 mm change would increase idle speed from 1K to 3.5k rpm. You might also take into consideration that the float needles may not be shutting off fuel 100% and that raising or lowering your test fuel jug would change the
"fuel head". Do you have your test gas jug hanging at the same height as the fuel tank would normally be in? I would look for the answer to your problem in two places. If your bike has the flanged induction tubes between the carbs and cylinder head, then it uses induction "O" rings on the mating surface. If those "O" rings are flattened, cracked, hard and consequently allowing an intake air leak, it would cause your problem.
It would only take a bad "O" ring on one cylinder to cause the problem.
If it is not an "O" ring problem, then it is a carb synch problem. Intake velocity is the key. For a constant volume, (idle rpm) if throughflow area is reduced (slides, or throttle valve opening reduced) then velocity increases and fuel pick up rate also increases, so mixtures become richer.
You can fine tune your mixtures for an even burn on all cylinders and consequently a smooth idle rpm by adjusting the carb synch's.

Earl

I know the floats are supposed to be set to 22mm. (1981 GS850GL)

If they are set to 24mm does that mean the engine gets too much fuel? Or too little? Or does it work the opposite way?

I've been working on the bike all day and am to the point I need to balance the carbs. My idle is way out of wack and seems to vary directly with the amount of fuel I have flowing from my fuel source. (I found a funnel with a valve at the bottom. )

When I fired the bike up initially it idled at about 1000 rpm, which I thought was pretty good. I left fuel flowing and cleaned up an area to sit in. When I cranked the bike up again, the idle shot way up -- to 3500. I shut the funnel off and the bike eventually dropped to 1000 or so.

I repeated this process a couple of times. The idle peaks and maintains 5000 for a short period of time.

I've got the carbs off and am resetting the floats. They may have been set more toward 24 than 22. As I was doing the adjustment I started to wonder if a setting of 24 would even cause my problem.

Am I grabbing at the wrong straw here?

As always, thanks for all the help.

[Anonymous]

Thanks for the quick reply.

I was in the process of trying to do a carb sync when I encounted the above problem. I thought I should do something about the idle before syncing the carbs.

My test jug was hanging well above where the tank normally sits. I'll drop it lower and sync the carbs tomorrow and see what I get.

Thanks again.

[moto_dan]

Thanks for the quick reply.

I was in the process of trying to do a carb sync when I encounted the above problem. I thought I should do something about the idle before syncing the carbs.

My test jug was hanging well above where the tank normally sits. I'll drop it lower and sync the carbs tomorrow and see what I get.

Thanks again.

Just a thought... do you have the vacuum line running to the petcock plugged?