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To Seafoam or not to Seafoam

Well..no go on the 550F. After letting the Seafoam soak in the carbs overnight, the carb still spurts gas out of the overflow tubes. I guess it's time to pull the carbs and have a look-see inside. I'll order new rubber intakes and rebuild kits to have on hand. Thanks for all the help.
 
nvr2old said:
Well..no go on the 550F. After letting the Seafoam soak in the carbs overnight, the carb still spurts gas out of the overflow tubes. I guess it's time to pull the carbs and have a look-see inside. I'll order new rubber intakes and rebuild kits to have on hand. Thanks for all the help.
Click to expand...

Twenty? years ago i revived a few CB400-4 bikes and found http://forums.sohc4.net/ an excellent site for tech help.
 
Another vote for seafoam I had two gummed up float bowls on my 1100 this year and threw some seam foam in and bike ran great!
 
I've not tried the letting Seafoam sit and work, all of my positive results came from riding the bike, kind'f letting the seafoam flush things out. Not say'in just letting it sit in there won't work, just know what has worked for me.
 
Yeah, same for me. If you can't get it running (and preferably ride it) then I don't think seafoam is the answer. :)
 
The bike actually runs great. I put about 20 miles on it after putting the Seafoam into the gas tank. The carb overflow continued to spit gas at a 30 second interval. That's when I thought I'd try Chuck's method of straight Seafoam in the carbs overnight, drain, fill with gas, go for a ride and see what happens. Still leaking out the overflow tube. I ordered a rebuild kit and new rubber intake manifolds for all four carbs, those should be here early next week. A Honda Tech friend that I have will help me pull the carb rack and we'll go in and see if we can figure out why it does what it does. Again, a shame because the bike really runs well.
 
Last edited:
Are you positive the tube isnt cracked? I put a piece of tubing on them and fill the bowl with water. then plug the hole off and blow in the tube. If its cracked youll see bubbles.
Secong thing is just maybe that carb needs a little higher float ht to shut off the fuel. Check the float needle to see that the little spring loaded tip is free and responsive. Service manual shows how to do a wet fuel check and that will give an indication if the fuels rising too high and spilling.
If you find a cracked tube clean it with some fine sand paper and solder the crack..done

http://manuals.sohc4.net/cb550/
 
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chuck hahn said:
Are you positive the tube isnt cracked?
Click to expand...

Make that, the overflow tube in the float bowl. It's very common for them to crack in Keihin carbs. Not overly difficult to replace, but a bit of a project.
 
I use Stabil every fall, and Seafoam every spring in everything I have with a 4 stroke engine. NEVER had a problem yet. That includes carbs, and FI.

*Side note: I typically use double the "recommended" dosage for both of them. EVERY YEAR, EVERY ENGINE.
 
Just a quick update on my carb problem. The good news is my Honda Tech friend was finally able to come for a visit from 100 miles away. We spent Saturday pulling the carb rack off the 550F and disassembling all 4 carbs. They were amazingly clean and easy to take apart. Installed a new needle and seat in the far outside problem carb and there was indeed a tiny chunk of crap that was keeping the float from closing the needle causing the overflow. He adjusted the float level while in there and bent the tab on the float just a pinch to push the needle closed a tad bit sooner. While the carbs were off I installed new factory rubber intakes coming off the head. Re-installed all 4 carbs and it works beautifully again. My friend, Lee, is an amazing mechanic. So nice watching someone who knows what they're doing, smoothly and correctly.
 
You and several others were correct about a piece of crap not allowing the needle to close for sure, Chuck. I was just hoping the seafoam would clean it up w/o having to pull the carbs..which it didn't. Both fuel lines are in good shape so they went back on. Amazing how small the obstruction was. All is good now. Bike runs great. Now that everything has been fixed up again comes the decision to sell the bike or keep it. 7 bikes is too many to maintain for me anymore. It's a beautiful cafe' and would be hard to let go of.. :blue:
 
I don't think Seafoam is designed to remove debris or trash, It just dissolves fuel residue build-up. Good thing it don't cost much to give it a try and in the end you got it straightened out. Congrats.
 
steve murdoch said:
Glad you got it sorted, Larry.
Now if you could just send me Lee's address. I'm willing to travel. :)
Click to expand...

I once saw Lee tear a brand new out of the crate 1981 CB900F down to the bare frame in one morning, I painted the frame red, and he reassembled it all in the same day. Maybe 8 hours of work total. He traded that for a 1982 CBX that he would adjust the valves on every 2,000 miles, just for fun
 
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