CB900C Carbs.

78CB400PA · 05-17-2011, 09:32 AM

So I found a 1980 900C that I am thinking about picking up haven't seen it yet going this weekend. But the owner is saying that he had a friend rebuild the carbs and now they are leaking. I am thinking I will just need the basic rebuild on them and cleaning. am I on the right track or is this more of an issue then I want it to be.
I re built the 2 carbs on the 78 hawk and feel I did a good job of getting everything fixed but they were just gummed up from sitting for 17 years in a barn with gas in them.
Any thoughts or advice would be nice before I pick up more of a headache then I want... or need.

nitroz71 · 05-17-2011, 11:24 AM

Shouldn't be too much of a headache, as long as you dont mind tearing down, cleaning, and rebuilding carbs. Does this bike fire up? If not, it might just be clogged jets. They get clogged, then the carbs will drain(leak) the excess gas out the overflow, happened on my CM/CB450SC/T :P

78CB400PA · 05-17-2011, 11:44 AM

Cool. He said it will fire up but he didn't want to run it to much since it is leaking gas. Ya i did the rebuild on the 2 so i guess it will be double the fun for the 4.. lol

krakoski · 05-18-2011, 06:10 PM

They could just need carb bowl gaskets which can be had for 20 bucks for all for, I just did it on my cb650 and worked great

nealethegreat · 05-24-2011, 12:52 AM

From what I've found, your float needles aren't sealing, or your floats are so gummed up they don't float.

Tazy Tiger · 05-25-2011, 10:26 PM

where is the fuel leaking from? if it's from your over flow tubes then it's more than likely your float needle and seats, take a bowl off one of the leaking carbs and hold up the float as if the bowl is full and see if it still leaks. Could also need the floats be checked with a float level gauge. Cheers Paul

05-17-2011, 09:32 AM	#1
78CB400PA Senior Member Join Date: Apr 2010 Location: Carlisle, PA Posts: 257	CB900C Carbs. So I found a 1980 900C that I am thinking about picking up haven't seen it yet going this weekend. But the owner is saying that he had a friend rebuild the carbs and now they are leaking. I am thinking I will just need the basic rebuild on them and cleaning. am I on the right track or is this more of an issue then I want it to be. I re built the 2 carbs on the 78 hawk and feel I did a good job of getting everything fixed but they were just gummed up from sitting for 17 years in a barn with gas in them. Any thoughts or advice would be nice before I pick up more of a headache then I want... or need.

05-25-2011, 10:26 PM	#6
Tazy Tiger Verified Join Date: May 2011 Location: Tasmania Australia Posts: 16	Fuel leak where is the fuel leaking from? if it's from your over flow tubes then it's more than likely your float needle and seats, take a bowl off one of the leaking carbs and hold up the float as if the bowl is full and see if it still leaks. Could also need the floats be checked with a float level gauge. Cheers Paul

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05-17-2011, 11:24 AM	#2
nitroz71 Verified Join Date: Apr 2011 Location: Georgia Posts: 17	Shouldn't be too much of a headache, as long as you dont mind tearing down, cleaning, and rebuilding carbs. Does this bike fire up? If not, it might just be clogged jets. They get clogged, then the carbs will drain(leak) the excess gas out the overflow, happened on my CM/CB450SC/T :P

05-17-2011, 11:44 AM	#3
78CB400PA Senior Member Join Date: Apr 2010 Location: Carlisle, PA Posts: 257	Cool. He said it will fire up but he didn't want to run it to much since it is leaking gas. Ya i did the rebuild on the 2 so i guess it will be double the fun for the 4.. lol

05-18-2011, 06:10 PM	#4
krakoski Verified Join Date: May 2011 Posts: 21	They could just need carb bowl gaskets which can be had for 20 bucks for all for, I just did it on my cb650 and worked great

05-24-2011, 12:52 AM	#5
nealethegreat Newbie Join Date: May 2011 Posts: 3	From what I've found, your float needles aren't sealing, or your floats are so gummed up they don't float.