Honda 1985 CD650SC N/Hawk-fuel in airbox - TwoWheelForum: Motorcycle and Sportbike forums
 
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post #1 of 4 (permalink) Old 06-30-2008, 02:27 PM Thread Starter
 
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Honda 1985 CD650SC N/Hawk-fuel in airbox

1985 Honda Nighthawk CB650SC.
Engine was running rough; smelled gassy (choke was off). When I stopped, bike fell over on engine guard and saddle bag -a little over 45%.
When righted, would not start. An hour later it did start and ran rough.
Changed plugs. Checked compression. Checked for spark. All OK.
Cleaned air filter - found something interesting. There is a screen toward the front of the airbox. In that area was a puddle of 'liquid' -mostly gas, I think.
After running engine and shutting off, I would hear a 'gurgle'. No idea where 'fluid' came from.
I did find that one of the 2 hoses that connect to the "T" connectors between two adjacent carbs was clogged with animal stuff. These hoses just lie in the area in front of the airbox and not sure what they are for. Expansion; overflow ??
Any info will be appreciated.
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post #2 of 4 (permalink) Old 06-30-2008, 05:44 PM
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Sounds like your carbs are overflowing. This is normally caused by debris in the needle/seat area but can also be from a bad float or just worn out needle/seat. Its possible you can drain the carbs from the bottom and flush out the problem but your carbs likely will need a bit of cleaning.

You can check each carbs fuel level by putting the correct size clear hose on the bottom nipple of each carb and opening the drain valve.

The hose off the side of the carbs that run down are for venting and overflow.

Check your oil, if the carb has been overflowing for a while your oil may be full of gas
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post #3 of 4 (permalink) Old 07-01-2008, 12:57 PM Thread Starter
 
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Greatly appreciate your reply. I did drain the floats and put some Seafoam into the fuel line and gas tank. Major improvement overnight !
One question- how would the overflow get into the oil?
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post #4 of 4 (permalink) Old 07-01-2008, 10:43 PM
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If fuel levels rise above the throttle body it runs down though the intake and will drain over time past the piston/rings.
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