GL1100 carb bowls leak.

[wally]

Hey All!
I am new to this forum and a new Goldwing owner also. I figure the best place for answers is where the pros are. It never ceases to amaze me that so much useful info can be found on a forum just by asking.
Anyway...I have just recently purchased a 1979 GL1000 with GL1100 carbs. First thing I did was pull out the carbs and give everything a good cleaning. When I put everything back together and put fuel to the bowls they ALL leaked quite a bit. I got new gaskets and have had the carbs in and out of the bike at least 5 times trying to stop the bleeding.
A process that is very simple has turned into a "pita"!! My question is, what am I doing wrong and how can I correct this!

 

[fcmusician]

Hey All!
I am new to this forum and a new Goldwing owner also. I figure the best place for answers is where the pros are. It never ceases to amaze me that so much useful info can be found on a forum just by asking.
Anyway...I have just recently purchased a 1979 GL1000 with GL1100 carbs. First thing I did was pull out the carbs and give everything a good cleaning. When I put everything back together and put fuel to the bowls they ALL leaked quite a bit. I got new gaskets and have had the carbs in and out of the bike at least 5 times trying to stop the bleeding.
A process that is very simple has turned into a "pita"!! My question is, what am I doing wrong and how can I correct this!

You need to make sure you adjusted the carb floats properly. Tip them sideways just a bit till the float valve just touches the float seat. Can't be any pressure on that float valve or you will get the incorrect height hence the leaking fuel problem .

 

[wally]

You need to make sure you adjusted the carb floats properly. Tip them sideways just a bit till the float valve just touches the float seat. Can't be any pressure on that float valve or you will get the incorrect height hence the leaking fuel problem .

Hi Dave. Thanks for the reply. Float bowls are adjusted to 15.5 mm. New float valves also.

 

[dan filipi]

Where do they leak, into the plenum or outside the carbs? Into the plenum suggests float valve issues, externally gasket or O ring problems.

Were these oem float valves? There are known problems like this with aftermarket float valves.

 

[pidjones]

Here is what I learned about GL1000 carb leaks - there are a lot of places for them to keak, so don't re-install them untill full bench tested. I use a 1/2 litter fuel cell and isopropyl alcohol (safer and less smelly in our basement garage). They should at a minimum pass an overnight test.

 

[mcgovern61]

How I tested my carbs. Lawn mower tank sitting on a chair elevated above the carbs. With the hose connected to the carbs, I always checked for leaks stationary first, and then I would lift the carbs, shake them and tilt them at least 30 degrees in all directions to simulate riding hard down the road. Great way to check them before spending all that time reinstalling on the bike and hoping for the best! The isopropyl alcohol trick is a good idea!

 

[wally]

Here is what I learned about GL1000 carb leaks - there are a lot of places for them to keak, so don't re-install them untill full bench tested. I use a 1/2 litter fuel cell and isopropyl alcohol (safer and less smelly in our basement garage). They should at a minimum pass an overnight test.

Great idea. These are GL1100 carbs but the same test should apply. Thanks.

 

[wally]

Where do they leak, into the plenum or outside the carbs? Into the plenum suggests float valve issues, externally gasket or O ring problems.

Were these oem float valves? There are known problems like this with aftermarket float valves.

Hi Dan.
I have the floats set at 15.5mm at a tilt like suggested. I put new aftermarket valves and inlet seats in and found the spring pressure on top of the new valves are very weak. I put the old valves back in. Very minimal distortion to the valve seat on the old original ones and a heavier spring tension too. All new o ring seals too, on pilot screws etc. Float bowl gaskets look really good and seem to seal nicely. I had new aftermarket ones so I installed them instead.
It is not until I install the carbs back into the bike that I have leaking. As the bowls become filled with fuel and the bike runs for about 3 mins I start to see weeping around the bowl seals which just gets worse as time goes by.
When I remove the carbs and look down the intake holes they are also wet with fuel. The engine runs relatively smooth during this but I cannot synch or tune anything while fuel is leaking.
When I shut the engine off the leaking dries up and doesn't leak unless engine is running. My float heights are correct. I have double checked several times.
Any input would be a help.

 

[mcgovern61]

A few things. After removing the carbs, check the bowl seals that they actually fit the bowl exactly. With the seal in the cover, look at it horizontally and be sure the seal protrudes up and out of the cover. These seals are a one time use and often cannot be compressed more than once or twice before they no longer seal. As far as leaking into the carb throats, that is because the float needles are not seating and gas is pouring into the engine. FYI, if that has been going on for a while, be aware that your oil may have thinned out with gas and it would be a good idea to change it when you get this resolved.

With the original OEM needle and seat, turn the needle sideways between your fingers and gently roll the rubber tip across Emory cloth while spinning the tip. There is often a small amount of imperfection on the old tips that prevents sealing against fuel pump pressure. You will also need to clean the OEM seat the same way except I twist the Emory paper into a Q-tip to get enough roundness to actually clean the seat. Doesn't take much to clean them so don't keep twisting the needle tip and seat too much! Wash off/out with carb cleaner spray. Normally, the OEM needles and seats can clean up and seal fine. Test them off the bike like mentioned above. Don't be gentle when testing. The bike isn't that gentle when in operation, hitting stuff on the road, leaning into curves, going up and down driveways, etc. If the carbs do not seal off the bike, you can pinpoint what condition is the issue.

 

[wally]

A few things. After removing the carbs, check the bowl seals that they actually fit the bowl exactly. With the seal in the cover, look at it horizontally and be sure the seal protrudes up and out of the cover. These seals are a one time use and often cannot be compressed more than once or twice before they no longer seal. As far as leaking into the carb throats, that is because the float needles are not seating and gas is pouring into the engine. FYI, if that has been going on for a while, be aware that your oil may have thinned out with gas and it would be a good idea to change it when you get this resolved.

With the original OEM needle and seat, turn the needle sideways between your fingers and gently roll the rubber tip across Emory cloth while spinning the tip. There is often a small amount of imperfection on the old tips that prevents sealing against fuel pump pressure. You will also need to clean the OEM seat the same way except I twist the Emory paper into a Q-tip to get enough roundness to actually clean the seat. Doesn't take much to clean them so don't keep twisting the needle tip and seat too much! Wash off/out with carb cleaner spray. Normally, the OEM needles and seats can clean up and seal fine. Test them off the bike like mentioned above. Don't be gentle when testing. The bike isn't that gentle when in operation, hitting stuff on the road, leaning into curves, going up and down driveways, etc. If the carbs do not seal off the bike, you can pinpoint what condition is the issue.

Hey Thanks for the info. There is a slight indent on the float needle tip if I look very closely. I will address that for sure. The seats are new so should be good. Thanks.

 

[DaveO430]

If the leak stops immediately when you shut the engine off it may be the crossover tubes between the carbs or the orings on the plenum.

 

[kerryb]

This is my static test setup. The pedestal is an office organizer on a swivel plate. Can turn the carbs for inspection to see where leak is. I think someone said, the fuel supply should be 4 or 5 feet above to simulate fuel pump pressure.

 

[wally]

This is my static test setup. The pedestal is an office organizer on a swivel plate. Can turn the carbs for inspection to see where leak is. I think someone said, the fuel supply should be 4 or 5 feet above to simulate fuel pump pressure.

Great idea. Thanks. I will use my lawnmower tank as a supply. If I fill it halfway should that still simulate enough fuel pressure?

 

[Denver]

I have a small hand pump that i use.
Pump the carbs up to 15 psi.
That's at the top fuel pumps range.
If the needle & seat hold the air pressure.
They will hold fuel pressure.

 

[kerryb]

This is a close-up of my carbs on the pedestal doing the "clear-tube test" there is a clear vinyl tube attached to the bowl drain. The drain screw is left open to show how much fuel is in the bowl by looking at the clear tube. The guys on the 750 forum use this to set or prove float level in action. I use it to prove the float valves are working. With the drain screws open, you can see the level in the carbs rise when you open the fuel valve on your "dummy" tank. If the float valves are at fault, this will show you.

Note: I make the tube fitting, most people find a plastic adapter at the aquarium store, or heat the tube to jam it into the outlet threads. Works well enough if you're persistant.

 

[pidjones]

Great idea. Thanks. I will use my lawnmower tank as a supply. If I fill it halfway should that still simulate enough fuel pressure?

Level in the tank is not as important as height of the tank above the carbs. Another thing that helps is a small flashlight for looking inside the carb throat and plenum for early indication from larger leaks before they start dripping out of the carbs.

 

[fcmusician]

Getting ready to use an Idea from another post. Rebuild your carbs. Then take a syringe like you get from a vet. Place it at the end of the fuel line going to your carb. Use water and force it into the carb like the pump would do. Look for leaks that way. No messy gas or alcohol to deal with. If it holds ok then flush out with gas in place of water as normal.

 

[wally]

Thanks for all the ideas and suggestions. I hooked up an aux tank and found there are other leaks I could not see with the carbs mounted to the bike. Leaking around the crossover fuel lines between carbs as well.
I’m going to have to split the carbs and replace the rubber seals between them all and try again.
I did the syringe thing too and float seals are all good.
Have a great New Years and I will post an update when I’m leak free!!

 

[fcmusician]

Thanks for all the ideas and suggestions. I hooked up an aux tank and found there are other leaks I could not see with the carbs mounted to the bike. Leaking around the crossover fuel lines between carbs as well.
I’m going to have to split the carbs and replace the rubber seals between them all and try again.
I did the syringe thing too and float seals are all good.
Have a great New Years and I will post an update when I’m leak free!!

Good luck Wally. Lot of pieces parts in those carbs. O rings galore! Sure you have heard this but Randakks kits are complete minus brass. Even includes those ever elusive super small cotter pins. did not need any brass part but all the O rings were pretty pitiful looking.

 

[85goldwing]

Dont forget the felt seals that hold the throttle plates. They will not cause a fuel leak, but getting the carbs balanced/synced will be a special kind of frustration.