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1986 Honda Shadow 500c
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Discussion Starter #1
So last night I noticed my bike (1986 Honda Shadow 500c) has been running rich. I don't need the choke for a cold start and you can smell gas from the pipes. What could be causing this an dhow can I fix it.


Thank You.
 

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1995 VT1100C2
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3,791 Posts
“It is a capital mistake to theorize before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts.” Sherlock Holmes

Perhaps you could add more information ie how are you deciding it is running rich (spark plugs?), how long have you had the bike, when did you notice it is running rich, what mods have you done and when.

G.
 

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1986 Honda Shadow 500c
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36 Posts
Discussion Starter #3
“It is a capital mistake to theorize before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts.” Sherlock Holmes

Perhaps you could add more information ie how are you deciding it is running rich (spark plugs?), how long have you had the bike, when did you notice it is running rich, what mods have you done and when.

G.
Well it can cold start without any choke. It also smells like gas at idle. I've had the bike since June. I haven't done any mods to it.
 

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1995 VT1100C2
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OK. First I would pull the spark plugs and examine. Make sure the electrodes are good or replace. Check the color and if sooty/black then you may be running rich. If you can post a photo of the plugs.

G.
 

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1983 Honda vt750 Shadow
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14,904 Posts
Did you examine the air filter and tubing for obstruction?
 

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1995 VT1100C2
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3,791 Posts
Those plugs actually look OK with a bit of carbon build up but I would consider replacing them. Keep the old plugs for reference and after a few hundred miles pull the new plugs again and examine.

My next suggestion after jpr (one way to test choke is to start the engine and let it idle. Now pull the choke on and off a few times. What happens to rpms?) and swifty (I would likely replace the air filter if you have not done so) would ask if you have a compression tester or leak down tester?

Is there any smoke at the exhaust when idling? Other than gas smell does the engine perform well ie no stumbling or bogging at any throttle position?
 

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Those plugs don't look bad especially if they are fairly old. The actually electrode looks fine with some carbon build up on the ceramic.

What does your idle sound like. Fast, slow, anything strange sounding?
 

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1986 Honda Shadow 500c
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36 Posts
Discussion Starter #10
-I tried the choke test and when the choke was up the rpms fell and when fully choked the engine died. As i brought the choke down it climbed in rpm.
-When started there was no smoke.
-The only time the engine gets bogged down is if I screw up changing gear
-At idle it is higher usually between 1500rpm-2000rpm

One of my choke cable ends was missing a spring so I went to ACE hardware bought and cut one to length. It seems to help the high idle but I'm not sure if that's due to a vacuum leak or due to the enrichener valve missing a spring.
 

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1995 VT1100C2
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3,791 Posts
I think your choke se valve may have been the problem and you could turn down your throttle stop screw a bit to idle closer to 1000 rpm
 

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1999 Shadow 750 ACE VT750CD3 Modified
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3,129 Posts
Agreed.
According to the service manual I have here it should be 1,100 rpm plus or minus 100 rpm.
That should be easier to obtain with the enrichment valve working correctly.
 
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