Float level lower than 21 mm consequences?

[Akifrend]

Hi all GL1000 riders and mechs.

I restored my 76 GL1k from being sat for around 9 years. New timing belts, spark plugs and water pump, carbs serviced and balanced, electrical system overhauled.
The bike starts at first try with choke when cold and without choke when warm, runs and idles great.
The problem: Fuel mileage is around 6-7 km/lt (around 15 miles per gallon).
Idle mixture screws are set using the idle drop procedure.
If I disconnect any of the 4 cil spark cable, the idle is clearly affected.
carbs float height set at 21 mm following randakks procedure on internet.
Spark plug are much darker than desired, really few poping in exhaust and no backfiring at plenum chamber.
Holding the gas consumption and spark plugs color, the bikes runs and feels terrific. So, I figured out that the bike is running too rich.
I've been thinking about lowering the carbs float height 2 o 3 mm (23 or 24 mm), it would make the gas-air mixture leaner and improve fuel mileage?
Is there any other way to improve fuel consumption?

Thanks a lot.

[Rambozo]

Changing the float level is not an ideal way to change mixture, that's what jets are for.
Do you have the stock air filter, intake and exhaust?
Have you replaced any jets and did you use genuine Honda parts?

[joecoolsuncle]

Changing the float level is not an ideal way to change mixture, that's what jets are for.
Do you have the stock air filter, intake and exhaust?
Have you replaced any jets and did you use genuine Honda parts?

yes. float level is a control. everything else is effected by that one setting. alter float level, and you lose control of the experiment. 15 mpg says you either got very leaky flaot valves, or you set the float lever incorrectly, ot you have big gaping holes where the main jet should be. did you fall victim to internet junk carb kits by chance?

[Akifrend]

Changing the float level is not an ideal way to change mixture, that's what jets are for.
Do you have the stock air filter, intake and exhaust?
Have you replaced any jets and did you use genuine Honda parts?

Hi Rambozo, thanks for your fast response.
Air filter and intake: Stock. Exhaust: generic exhaust adapted.
Jets are original, I checked jet numbers and all are those mentioned in the shop manual for 758A carburators.

Any guide would be appreciated. Thanks in advance

[Akifrend]

Changing the float level is not an ideal way to change mixture, that's what jets are for.
Do you have the stock air filter, intake and exhaust?
Have you replaced any jets and did you use genuine Honda parts?

yes. float level is a control. everything else is effected by that one setting. alter float level, and you lose control of the experiment. 15 mpg says you either got very leaky flaot valves, or you set the float lever incorrectly, ot you have big gaping holes where the main jet should be. did you fall victim to internet junk carb kits by chance?

Hi Joe, I bench checked needles with 3 psi and got no leak, I´m inclined to incorrect float levels hypotesis.

I live in Venezuela and here is a challenge to adquire spare parts for vintage motorcycles, It is almost a dream to get one of Randakks carb kits, so I kept original everything I could when servicing carbs, to have a motorcycle like a GL1000 here is almost a dream.

Next weekend i will try to lower float levels and keep you posted about the results of this experiment, I cross fingers they are just too high.

Really appreciate your advice.

[joecoolsuncle]

did you bench test with carbs assembled and in a position mimicking installed? tested fuel pump pressure? 15 mpg and black plugs is a huge amount of fuel going through.
while you have the float bowls off, check the main jets for correct size........not numbers on jets, but actual measurements. hope you find the problem, i wanna see pics of goldwinging in venzuela!

[Akifrend]

did you bench test with carbs assembled and in a position mimicking installed? tested fuel pump pressure? 15 mpg and black plugs is a huge amount of fuel going through.
while you have the float bowls off, check the main jets for correct size........not numbers on jets, but actual measurements. hope you find the problem, i wanna see pics of goldwinging in venzuela!

did you bench test with carbs assembled and in a position mimicking installed?
Yes I did.

tested fuel pump pressure?
No, I didn't. Fuel pump failure could be low pressure or leak, I don't see how a pump failure could cause low fuel mileage.

15 mpg and black plugs is a huge amount of fuel going through.
You can say that again !!!

while you have the float bowls off, check the main jets for correct size........not numbers on jets, but actual measurements.
Sound nice, but how do I measure those tiny hole diameters? Is there a jet holes measuring device?

hope you find the problem, i wanna see pics of goldwinging in venzuela!
Thanks, there are really few GL here in my country, I could send pics of my baby when I post the results of the float height adjustment.

[Rambozo]

tested fuel pump pressure?
No, I didn't. Fuel pump failure could be low pressure or leak, I don't see how a pump failure could cause low fuel mileage.

while you have the float bowls off, check the main jets for correct size........not numbers on jets, but actual measurements.
Sound nice, but how do I measure those tiny hole diameters? Is there a jet holes measuring device?

You are checking the fuel pump to make sure it doesn't have too much pressure. Typically, 1 or 2 psi is all you need.

Yes, you can check the jets with gauge pins, or the shank of drill bits. Compare to a new jet. I have seen jets go oversize from corrosion. You can usually tell because the inside hole will be rough, not a smooth machined surface. On old bikes that you don't know the history of, someone could have drilled out the jets, too.

[cfairweather]

With that amount of fuel going through the carbs, it makes me suspicious of the o-rings leaking around the main and/or secondary fuel jets. These o-rings must have a good seal, so the jet must fit snugly. You may have to use a slightly different size to make them fit.

[Akifrend]

Yes, as fact, I revised everything all of you mentioned, search at local stores for jets orings but got no size excat coincidences, so I had to adapt some orings grinding then with a drill and 2000 grain sandpaper, Yes, it will sound nuts for some of you, Here in my country there are not resources for this king of vintage vehicles.

About float levels, I adjusted them to 23,5 mm instead that 21 mm. The gas mileage improved but the bike doesn´t rev over 6000 rpm in any gear, I figured out fuel starvation, below 6000 runs great and starts easy being overnight cool with choke.

After a 20 miles ride, I removed the cilinders manifold and noticed a small fuel pond in the intake valve area, I guess it is not normal, but it seem to be contrary to low float levels or maybe I still have jet orings problems.

I´ve been busy at my job and not gotten enought time for continuing working on this issue on my bike. Any suggestion will be appreciated and considered.

Thanks in advanced.

[cfairweather]

From what you have described about gas in the intake, you probably have a float valve leaking or a fuel plenum seal that is bad. Do this simple test: Put the bike on the center stand. Remove the air filter and then start the motorcycle. Then look down into the plenum with a flashlight so you can see the bottom. Then rev the engine and run the bike for a few minutes. If you see any gas in the plenum, you have a problem. The cause it a bad plenum seal or the float valve is not shutting the fuel off. When this occurs, the fuel overflows out the top of the carburetor and will often run into the plenum. You can use 4 clear tubes connected to the float bowl drain hole to check the actual level of fuel in the carburetors. The level should be at the bottom edge of the bowl rim. This is the lowest side of the carburetors and the side near the chrome brackets. Hope this helps.

[Maz]

Too much fuel has been mentioned a lot, but what about 'not enough air'?
Maz

[Akifrend]

Too much fuel has been mentioned a lot, but what about 'not enough air'?
Maz

Ihave tested even without air filter, no difference. Thanks for your suggestion

[Akifrend]

From what you have described about gas in the intake, you probably have a float valve leaking or a fuel plenum seal that is bad. Do this simple test: Put the bike on the center stand. Remove the air filter and then start the motorcycle. Then look down into the plenum with a flashlight so you can see the bottom. Then rev the engine and run the bike for a few minutes. If you see any gas in the plenum, you have a problem. The cause it a bad plenum seal or the float valve is not shutting the fuel off. When this occurs, the fuel overflows out the top of the carburetor and will often run into the plenum. You can use 4 clear tubes connected to the float bowl drain hole to check the actual level of fuel in the carburetors. The level should be at the bottom edge of the bowl rim. This is the lowest side of the carburetors and the side near the chrome brackets. Hope this helps.

I did this plenum test you mentioned, plenum gets "wet", I mean, no liquid in the plenum as did once in the past, but i touch the plenum floor and feel my finger with something like dew but more vapor than liquid, Sorry if I don´t make me clear.

But I found another problem in the bike, it is splashing oil from the timing mark cap when removed, I then opened the oil cap (where you fill the engine oil) and I can feel the pressure of the cilinders in the carter, So I guess my bike has a compression problem (cylinder rings), so, game is over for now .

Thanks a lot for your advice, happy new year

[DenverWinger]

But I found another problem in the bike, it is splashing oil from the timing mark cap when removed, I then opened the oil cap (where you fill the engine oil) and I can feel the pressure of the cilinders in the carter, So I guess my bike has a compression problem (cylinder rings), so, game is over for now .

Thanks a lot for your advice, happy new year

This is normal - I've forgotten to replace the oil fill cap once - when I started the engine oil went everywhere. The timing mark cap will do the same thing.

Goldwing engines will very rarely have bad piston rings, even after years of sitting.