How to determine if plenum gasket is bad


Information and questions on GL1100 Goldwings (1980-1983)
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reb54
Posts: 26
Joined: Wed Jan 20, 2010 11:53 pm
Location: Carrollton, Texas
Motorcycle: 1981 GL1100 Standard

How to determine if plenum gasket is bad

Postby reb54 » Sun Mar 22, 2015 6:05 pm



Bike is a 1981 1100 standard.
Have maybe two years on a Randakk carb rebuild kit. Leaking a nice little stream from what appears to be between #1 & #3 carbs.
Just had the carbs off and checked all of the float levels and replaced one pinched float bowl gasket. A main jet was also found in the bottom of float #1. Cleaned everything up and reinstalled the carbs, naturally the "leak" is still there. I did notice that while the bike was running, air box off, the area between the halves was wet with gas.
Is there an easy way to test to see if the plenum gasket needs replacing?
Appreciate any input.

Randal Brown
1981 standard
Carrollton, TX



reb54
Posts: 26
Joined: Wed Jan 20, 2010 11:53 pm
Location: Carrollton, Texas
Motorcycle: 1981 GL1100 Standard

Re: How to determine if plenum gasket is bad

Postby reb54 » Sun Mar 22, 2015 7:02 pm

An update to the "leak"
Placed newspaper inside the plenum and started the bike. The paper stayed dry. I could see gas coming from the bottom, inside of carb #3 where it attaches to the plenum and running toward the plenum center and dripping (at least that is what it appears to come from).
On my first test where the plenum was wet with gas, could that have been caused by running the bike with the choke on?

Thanks / Randal
1981 Standard
Carrollton, TX

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auctioneeral
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1981 GL1100 full dresser
Both getting restored

Re: How to determine if plenum gasket is bad

Postby auctioneeral » Sun Mar 22, 2015 7:36 pm

You could do a bench fuel test. Lay carb rack level on workbench and run a fuel line off carb up to a small lawn mower fuel tank about 4-5 ft. or hook up fuel line at carbs and run a fuel line about 5 feet higher then carb rack and pour fuel in it. Either way fills the carbs. and floats shut fuel off. And then you can see better on were fuel is leaking.

The plenum only has the one gasket for joining the 2 halfs together. But there is 2 O-rings on the plenum side of #3carb when you bolt it to the plenum.
Or it could be the fuel cross over tubes.

f1xrupr
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Motorcycle: 1980 gl 1100 Std. Vetter

Re: How to determine if plenum gasket is bad

Postby f1xrupr » Sun Mar 22, 2015 8:06 pm

Hmmm...Randakk carb kit leak in 2 years? I bet a lot of people will be curious what fuel, treatment, additives, or none, tranny fluid....etc you use. You probably know this-one of those o-rings between the carb and plenumn is a feed line, so it can leak even if carbs are ok, and, the other is the accelerator pump, and it would leak more if you work the throttle (that will also flood it out you know).
My exercise bike is a goldwing.

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spiralout
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1980 GL1100I (with '77 1000 engine)
1996 GL1500 SE

Re: How to determine if plenum gasket is bad

Postby spiralout » Sun Mar 22, 2015 8:47 pm

f1xrupr wrote:Hmmm...Randakk carb kit leak in 2 years? I bet a lot of people will be curious what fuel, treatment, additives, or none, tranny fluid....etc you use.

My money is on the quality of the installation, not the effects of chemicals on the viton. Bowl gasket problem, jet loose in the bowl, now another leak...

f1xrupr
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Re: How to determine if plenum gasket is bad

Postby f1xrupr » Sun Mar 22, 2015 8:55 pm

Yeah, good thought...I wonder...who supplied the kit-if you catch my drift?
My exercise bike is a goldwing.

reb54
Posts: 26
Joined: Wed Jan 20, 2010 11:53 pm
Location: Carrollton, Texas
Motorcycle: 1981 GL1100 Standard

Re: How to determine if plenum gasket is bad

Postby reb54 » Sun Mar 22, 2015 9:49 pm

To give a bit more information.
The carb rebuild kit was purchased directly from Randakk.
Have not used any carb cleaner/treatment since the rebuild. I have used Marvel Mystery oil on ocassion 2oz, per 5 gal.
I use the E10 ethonal and never the 15.
Oil used is Shell Rotella 15w40 or the equivalent Delo, changed every 3,00 miles.
I also have Randakk's reusable gas filter and spin-on oil filter adapter (can't say enough good about it).

Randal

reb54
Posts: 26
Joined: Wed Jan 20, 2010 11:53 pm
Location: Carrollton, Texas
Motorcycle: 1981 GL1100 Standard

Re: How to determine if plenum gasket is bad

Postby reb54 » Sun Mar 22, 2015 9:53 pm

Seems like if the rebuild was not up to snuff, the problem would have shown up thousands of miles ago.
I am interested in figuring out what my problem is.....regardless if it is something I have done.

Randal

reb54
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Re: How to determine if plenum gasket is bad

Postby reb54 » Sat Mar 28, 2015 5:16 pm

Just tested my carbs on my work bench. Looks like it is leaking from above the accelerator pump. Does not leak with the gas on just sitting there. Leaks when I activate the accelerator pump, I can see the gas shoot into the carb body. After using the accelerator pump it leaks above the pump and drips off of the bottom of the pump. The leak does not appear to be coming from the bottom gasket on the accelerator pump. If an accelerator pump is bad does it some how shoot gas above the pump or exhibit any of the listed symptoms?
I am using a mirror and flashlight to try and see exactly where the gas is leaking from (bottom side of the carbs).

Randal

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auctioneeral
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Motorcycle: 1981 GL1100 nake
1981 GL1100 full dresser
Both getting restored

Re: How to determine if plenum gasket is bad

Postby auctioneeral » Sat Mar 28, 2015 6:32 pm

I would check the O-ring.
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reb54
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Re: How to determine if plenum gasket is bad

Postby reb54 » Sat Mar 28, 2015 7:23 pm

Thank you for the reply, will definately check it out.

Randal

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Overdog
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74 BMW R90/6

Re: How to determine if plenum gasket is bad

Postby Overdog » Sun Mar 29, 2015 8:14 am

reb54 wrote:Just tested my carbs on my work bench. Looks like it is leaking from above the accelerator pump. Does not leak with the gas on just sitting there. Leaks when I activate the accelerator pump, I can see the gas shoot into the carb body. After using the accelerator pump it leaks above the pump and drips off of the bottom of the pump. The leak does not appear to be coming from the bottom gasket on the accelerator pump. If an accelerator pump is bad does it some how shoot gas above the pump or exhibit any of the listed symptoms?
I am using a mirror and flashlight to try and see exactly where the gas is leaking from (bottom side of the carbs).

Randal


EXACTLY what mine was doing. Last summer I began smelling raw gas when I was riding.....no drips but the #3 bowl was a little wet. As the season went on it got worse. Over the winter I started the bike in the garage and saw gas now dripping. When I twisted the grip gas squirted upward from around the accel. pump shaft. When I tore the carbs apart I found that somebody had been in there before and used sealer....probably silicone....on the gaskets. The chamber of the accel. pump was filled with crud.

reb54
Posts: 26
Joined: Wed Jan 20, 2010 11:53 pm
Location: Carrollton, Texas
Motorcycle: 1981 GL1100 Standard

Re: How to determine if plenum gasket is bad

Postby reb54 » Sun Mar 29, 2015 8:39 am

Thanks for your reply. Something else for me to check out. At least I am encouraged that the leak is about to be fixed......

Randal

reb54
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Joined: Wed Jan 20, 2010 11:53 pm
Location: Carrollton, Texas
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Re: How to determine if plenum gasket is bad

Postby reb54 » Wed Apr 01, 2015 9:18 pm

Auctioneeral, looks like you were right about the o-ring! I removed the float bowl on #3 carb and sure enough, the o-ring was missing. I have replaced the o-ring and it did not appear to leak. I am going to let it sit over night and test again tomorrow. Hopefully this will take care of the leak...... I love it when I finally make some progress.

Thanks for the information....looks like I am going to be able to attend our camp out in the hill country here in Texas.

Randal

reb54
Posts: 26
Joined: Wed Jan 20, 2010 11:53 pm
Location: Carrollton, Texas
Motorcycle: 1981 GL1100 Standard

Re: How to determine if plenum gasket is bad

Postby reb54 » Sun Apr 05, 2015 12:23 pm

I am extremely happy to report that the carbs have been installed and more importantly do NOT leak!!!!! Thanks to all who responded......
Will start a new thread concerning my water pump.

Randal




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