Extreme gas smell specific to carbs


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kndw
Posts: 123
Joined: Sat Jun 19, 2010 2:56 am
Location: Driebergen, Utrecht
Motorcycle: 1976 GL1000 Gran' Luxe

Extreme gas smell specific to carbs

Post by kndw » Sat Nov 12, 2016 1:17 pm



Dear all,

When I bought my '76 GL1000, it had a set of '78 carburetors on it. I didn't know this then, nor whether it mattered at all, until I read on Randakk's website that carbs shouldn't be mixed between early and later wings because of a change in venturi size. In principle the bike ran fine, and fuel consumption was acceptable @ 35 us-mpg, but it always smelled of gas badly when running. And, as Randakk states: 'Why settle for OK, when you can have stellar performance?'.

So, I bought a set of used carbs from the proper year and rebuilt them. With the 'new' set, the fuel smell is gone. Unfortunately, it only runs okay-ish. Off-idle is rough -despite the off-idle fix being implemented. I suspect the aftermarket jets/needles. While I search for OEM jets/needles and tear the '76 carbs apart again, I'd like to install the '78 set again such that I can at least go for a ride.

However, I'd first like to figure what caused the stench now they're on my workbench. I bench-tested them by running a fuel line from about a meter above the carburetors, and could not find any leaks. What could be the cause of the fuel smell?

Thanks for any help!



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Fred Camper
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Location: Metro Detroit, MI
Motorcycle: 1977 GL1000, 1976 LTD GL1000

Re: Extreme gas smell specific to carbs

Post by Fred Camper » Sat Nov 12, 2016 9:01 pm

Since it just happens when running and the fuel pump just pumps when running, it is possible that the float bowl seats leak under pump pressure.

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Fred Camper
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Re: Extreme gas smell specific to carbs

Post by Fred Camper » Sat Nov 12, 2016 9:05 pm

Did you happen to use Mike Nixon's rebuild guide or Randakks video when you rebuilt the 1976 carbs? If not, those are a great investment and that is the direction I would suggest.

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dingdong
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Re: Extreme gas smell specific to carbs

Post by dingdong » Sun Nov 13, 2016 9:17 am

Unless your set of 76 carbs had aftermarket jets installed when you purchased them you have a perfectly good set of jets. There is no reason to replace the old jets. The only thing you should need to replace are seals and float valves. The float valves should be OEM.
Tom

John F. Kennedy would be impeached by todays liberal Democratic socialist party.

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Overdog
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Re: Extreme gas smell specific to carbs

Post by Overdog » Sun Nov 13, 2016 8:26 pm

Not sure how this relates to GL1000 carbs, but, on my 1100 I was getting a strong smell of raw gas for the most part of the first summer I had it....no leaks to be found....until the accelerator pump diaphragm got bad enough that gas was leaking down off of #3 carb....the port in the bowl had clogged and gas was pumping up the rod that works the diaphragm and out the top

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SnoBrdr
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Location: Providence, Rhode Island
Motorcycle: 1978 GL 1000

129K Original Owner

Re: Extreme gas smell specific to carbs

Post by SnoBrdr » Sun Nov 13, 2016 9:19 pm

Overdog wrote:Not sure how this relates to GL1000 carbs, but, on my 1100 I was getting a strong smell of raw gas for the most part of the first summer I had it....no leaks to be found....until the accelerator pump diaphragm got bad enough that gas was leaking down off of #3 carb....the port in the bowl had clogged and gas was pumping up the rod that works the diaphragm and out the top
No accelerator pump in GLs pre 1100s.

kndw
Posts: 123
Joined: Sat Jun 19, 2010 2:56 am
Location: Driebergen, Utrecht
Motorcycle: 1976 GL1000 Gran' Luxe

Re: Extreme gas smell specific to carbs

Post by kndw » Fri Nov 25, 2016 12:20 pm

Thanks for the suggestions.

As to why I replaced some parts: the main nozzles needed to be replaced because they turned out to be damaged, and three of the main jets were so oxidized in the housing that they broke basically upon touching them.

I'll see what happens when I connect the carbs to the fuel pump.

Also, I found that one of the caps at the end of the shaft that moves the throttle plates was loose. Is that a potential culprit?

kndw
Posts: 123
Joined: Sat Jun 19, 2010 2:56 am
Location: Driebergen, Utrecht
Motorcycle: 1976 GL1000 Gran' Luxe

Re: Extreme gas smell specific to carbs

Post by kndw » Sat Dec 01, 2018 4:35 am

A late update:

The bike is now parked for winter, and I noticed now that it stank regardless of the set of carbs :oops:

It turns out that the smell came from the fuel gauge sending unit. I had the gas tank filled to the brim, and there was fuel pooling on top of the sending unit. This probably means that the gasket has deteriorated.

Hope this may one day help someone.



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