1982 cb450sc leaking gas

[elstraitjacket]

hey everybody.  i have a 1982 nighthawk 450.  bike's been running fine, but today i went out for a ride, and while stopped at a light i noticed that gas was leaking at a pretty good clip from the drainage hose on the the left carb.  i rode her home and turned the petcock off and the flow stopped.  i checked the screws that open the bleeder and they were tight. other boards/pages i've viewd all seem to point to a sticky float, which is confusing and irritating since i had the carbs cleaned by a mechanic about a month ago.  any suggestions?

also, i have no real knowledge of bikes since this is my first, but i work on my car fairly regularly.

thanks alot!

[elstraitjacket]

i may have to give that a shot.  also, i failed to mention that i had a straight line going from the petcock to the carbs.  i pulled the filter earlier because it was running rough-thought maybe the filter was bad, so i pulled it and went straight from petcock to carbs.  since it continued to run rough, i figured that wasn't the problem and decided it was probably better to have a fuel filter on there.  i only noticed the leaking after i replaced the filter.

[elstraitjacket]

ok.  do you think i should pull the tank off and pour seafom straight into the carbs before trying to take them apart or should i just run it through the gas tank?

[Bumblebee]

Runs horrible and fuel leaking out the drain hose. Sounds like a sunk float or the float valve is jammed open for some reason. Not confusing at all. As for how the technician cleaned the carburetors, ask him before thinking it's a mystery. He could have done nothing more than spray carburetor cleaner into the intake as far as you know.

Sticky float is an easy fix if you have any ability at all to turn a wrench.

Drain and pull the carburetors, flip them upside down, take the offending float bowl off (3 screws usually) remove the float and clean out the float chamber and float valve, reassemble, done. An hour tops if you've never done it before. Two hours if it's a pain to get them off and on without previous experience.
On second thought, you don't even have to completely remove the carburetors and flip them over. Just get them far enough off to access the float bowls and see what you're cleaning. You don't even have to disconnect the throttle or choke cables for that.

[elstraitjacket]

sweet.  i think i might just take off the carbs and see what's up with the float first thing in the morning.  it's not complicated, but a huge pain in getting the carbs back into the rubber boots going into the block/air box.  i don't really have time to burn two tanks of gas to see if the seafoam will do the trick.  thanks for all the suggestions, i'll let you know how things go...
-d

[niteman]

http://nighthawk-forums.com/index.php/topic,1926.msg20277.html#msg20277

First off, welcome to the forum. The above is a link to how I removed the carbs off my 450sc. It wasn't really all that hard, and took about 10 minutes to do. Hope this helps.

[elstraitjacket]

Cool. thanks, i'll check it out!

[ninskrillz]

grr it seams i have the same problem.... Ive got some cleaner running through it right now, if it doesnt go away in a couple days, im buying a dynojet kit and rebuilding be some carbs.

[detdrbuzzard]

grr it seams i have the same problem.... Ive got some cleaner running through it right now, if it doesnt go away in a couple days, im buying a dynojet kit and rebuilding be some carbs.

just clean or rebuild the carbs. a dynojet is not a rebuild kit

[ninskrillz]

i know that i already have a rebuild kit that came with it, but i might as well put a jet kit in while im rebuilding.

[ninskrillz]

if only the left carb is leaking i should only have to rebuild the one?

[gammer]

How do you know its only the left carb thats leaking?
The over flow tubes cover two carbs each.
Besides, if you are putting a DynoJet kit in it, you will have to do all of them at the same time.

[ninskrillz]

i dont think im doing the jet kit yet, i want to get this taken care of now as it seems to be leaking more now. i guess i'll just have to buy two rebuild kits and rebuild both of the left ones.

[gammer]

My guess is that you have some gummed up gas in the float bowls. As the floats on your bike are plastic and cannot be adjusted. If it were me, I'd at the very least take the carbs off the bike, pull off the foat bowl, floats, pull out all the jets, pull out the slides, soak all the parts and then blow every nook and cranny out with compressed air.

[ninskrillz]

soak all the parts in what?

[gammer]

I think GUNK makes a product that you can soak it in. And you should be able to find it at WalMart in the motor oil section.

I've used diesel fuel in the past with good success...it does a good job at removing gunk and grease. However, it stinks and you want to avoid getting it on your skin and clothes and you will need to wear rubber gloves. But, that's a given for any product that you are going to use to do this.

[Bumblebee]

I don't soak anything. I just take the parts off and use a q-tip, a T-pin, a paper towel and isopropyl alcohol to clean the parts manually. They'll be clean in minutes then you can put it all back together.

Dirt simple, cheap and you don't generally get gassed to death or have your hands melt off. Just don't put your nose to the bottle and you'll be ok...though it's kinda funny when a dog insists on helping and wants to smell the open bottle.

[gammer]

Good call Bumblebee...yeah, alcohol works good too.

Also one of those welder tip cleaning tools helps...but a t-pin is much cheaper

[ninskrillz]

ok ive said this before but im by all means not a mechanic, can either one of you guys give a detailed explaination of what parts to remove from the carbs before cleaning, pictures are always a big help. Thanks a lot guys, i just got the carbs off and they look pretty clean, i know they were rebuilt before i bought it so i dont think i have to go to that length.
Will I have to resync the carbs when all of this is said and done? If so i need to buy a sync tool.

[elstraitjacket]

so i pulled off the carbs and everything looks clean.  i shot carb cleaner in the bowl and in the passage where the float needle goes.  i decided that maybe the old "take it apart put it back together" trick may have been enough...and then i realized that i lost a screw.  just disappeared.  i thought it went into the crankcase so i pulled it and looked around.  nothing.  at this point i was ready to kick a hole in my fence.  after having looked around for about 45 minutes it started storming.  i went inside and ate a popsicle and that is how far i've gotten today. 

[gammer]

What screw is it?
And how would it have gotten into the crank case?

[niteman]

i decided that maybe the old "take it apart put it back together" trick may have been enough...and then i realized that i lost a screw.

Oh man, that sucks! Hope you find it. BTW, which "screw" did you lose?

[elstraitjacket]

it was one of the 3 float bowl mounting screws. i unscrewed it and it fell from my grasp and it just freaking disappeared.  didn't hit the ground...i assumed it went in there and when i didn't see it on the ground i had to look in the crankcase.  yeah it totally sucks.  i have to work in a minute here but i guess i'll go to lowes tomorrow.   grrrrr

[niteman]

Yeah, Lowe's will definitely have one that will work. Sucks that you can't find the one you dropped...hope it's not really in the crankcase and it just rolled out of sight. Good luck.

[elstraitjacket]

yeah i looked in there and didn't see it so it probably did roll out of sight.  i turned the wheel and tried to see if maybe it just got stuck to the chain, but nothing.  it's just weird-usually you find a lost screw/bolt/nut even though it takes a long ass time.  hopefully lowes has what i need.