Strong exhaust on deceleration puzzle


Information and questions on GL1200 Goldwings (1984-1987)
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jtimgrant
Posts: 77
Joined: Sat May 25, 2013 7:24 am
Location: Greensboro NC.
Motorcycle: 1987 GL1200 Aspencade

Strong exhaust on deceleration puzzle

Postby jtimgrant » Fri Mar 21, 2014 7:32 pm



My old 87 has had a strong exhaust smell on decel since the carbs were rebuilt. The slow air cutoff was replaced. It and the secondary air system both hold vacuum and seem to operate as designed. so I tried an experiment today during a 250 mile ride. I completely disabled the slow air cutoff and the secondary air system by removing the vacuum hose. Could tell almost no difference except the strong smell was much more tolerable. But there was no exhaust popping as you would expect. This makes no sense to me. Any ideas?

If there is no popping during decel with the system disconnected would it hurt to run it disconnected?

Other than this the bike runs perfectly. Gas mileage ran 53mpg on today's ride.

t



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WingAdmin
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Re: Strong exhaust on deceleration puzzle

Postby WingAdmin » Sat Mar 22, 2014 8:57 am

jtimgrant wrote:My old 87 has had a strong exhaust smell on decel since the carbs were rebuilt. The slow air cutoff was replaced. It and the secondary air system both hold vacuum and seem to operate as designed. so I tried an experiment today during a 250 mile ride. I completely disabled the slow air cutoff and the secondary air system by removing the vacuum hose. Could tell almost no difference except the strong smell was much more tolerable. But there was no exhaust popping as you would expect. This makes no sense to me. Any ideas?

If there is no popping during decel with the system disconnected would it hurt to run it disconnected?

Other than this the bike runs perfectly. Gas mileage ran 53mpg on today's ride.

t


Is the exhaust smell coming from the carb area, or is it being sucked up from the exhaust pipes? Some aftermarket accessories (windshields especially) can create vortices that will suck exhaust up into the cockpit in some instances.

jtimgrant
Posts: 77
Joined: Sat May 25, 2013 7:24 am
Location: Greensboro NC.
Motorcycle: 1987 GL1200 Aspencade

Re: Strong exhaust on deceleration puzzle

Postby jtimgrant » Sat Mar 22, 2014 9:56 am

It is being sucked up into the cockpit but the bike is completely stock. No aftermarket stuff at all. It is far worse with the cutoff connected so I'm leaving it disconnected as long as I'm getting no afterburn. I am considering installing exhaust extensions to see if that remedies the problem.

Thanks for replying.

Tim

triwing
Posts: 72
Joined: Tue Oct 30, 2012 3:24 pm
Location: Stow Ohio
Motorcycle: 84 gl 1200,87int,91asp

Re: Strong exhaust on deceleration puzzle

Postby triwing » Sun Mar 23, 2014 9:19 am

Depending on who & how much they know about these old scooters means a lot in a rebuild & or adjustments. Bought an 84 years ago, that did same thing,farted,sounded like a 22 shell.Got to looking,plugs on air mixture screws were gone,& set way too rich.Talked to PO said a dealer had worked on mixers (carbs) to make it run better.But with your MPG don't sound quite the same.Did you replace small O ring & clean area around it when you replaced air cut off ? Small hole into side of carb assembly needs to be clear,for it to work properly.Hope this helps.

jtimgrant
Posts: 77
Joined: Sat May 25, 2013 7:24 am
Location: Greensboro NC.
Motorcycle: 1987 GL1200 Aspencade

Re: Strong exhaust on deceleration puzzle

Postby jtimgrant » Sun Mar 23, 2014 9:33 am

triwing wrote:Depending on who & how much they know about these old scooters means a lot in a rebuild & or adjustments. Bought an 84 years ago, that did same thing,farted,sounded like a 22 shell.Got to looking,plugs on air mixture screws were gone,& set way too rich.Talked to PO said a dealer had worked on mixers (carbs) to make it run better.But with your MPG don't sound quite the same.Did you replace small O ring & clean area around it when you replaced air cut off ? Small hole into side of carb assembly needs to be clear,for it to work properly.Hope this helps.


Hi Triwing,

You got me on this one --- small o-ring on air cutoff? Are you referring to the slow air cutoff on the underside of the plenum? If so, mine only had a diaphragm and I replaced that with a new one. There was no o-ring.

As for the small holes in the carbs I suppose you mean the ones just below the venturi in the front of the carbs. There are two holes there - one is blocked with a small ball - the other is open.

Thanks,

Tim

triwing
Posts: 72
Joined: Tue Oct 30, 2012 3:24 pm
Location: Stow Ohio
Motorcycle: 84 gl 1200,87int,91asp

Re: Strong exhaust on deceleration puzzle

Postby triwing » Mon Mar 24, 2014 8:40 pm

Your right.cut off valve, & adjustments on 84, accelerator pump on 91 had the o ring on side of body if memory serves, but sometimes not so good. Anyway adjustments, & cut off valve stopped back fires,needle & seats stopped leaks.




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