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1978 cb750 four k carbs.

fatoldo

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long island NY
hello all, I have rebuilt my carbs on my 78 cb750. the bike is back together and it runs. At first it had no power. then I adjusted the 4 carb screws till it seemed to have power. Rode it up and down the block a few times and all seemed fine. today, 2 months later i started the bike up. It started very easy. but after warming it up it didnt have enough power to get me up my drive way. Also one other thing. Before I started it i turned on the fuel valve. after a minute of it just sitting there gas started coming out of a hose. not sure what hose but it wasnt one of the bowl hoses.
History of the bike. I just got it last summer. it was running but again seemed to have no power which is why i took off the carbs. The bike sat since 2005 outside , uncovered till i bought it this past summer. its got 8k miles on it. it looks like hell but its all there and just needs TLC to make it nice again. I have rebuilt a carb or two on cars but never a bike. this was my first. I took them down to nothing and replaced all parts that came in the kits. As it is now, the set screws are turned out about 4 to 5 turns. It seemed to run the best this way 2 months ago. I thought it was a bit much (the4 or 5 turns out) but it seemed to like it. The original way i found the bike it was 3 turns out on the screws.

any ideas?
 
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hey this is Zach i have a 82 cb750sc nighthawk and a 82 cb900 custom having replaced all the parts in the carbs you need to make sure that you have the float levels set correctly or else you will flood the carbs out. If your floats aren't set to the proper float height specifications playing with the idle set screws will only change the idle of the bike it will run half assed for a lil while or not at all, but all it is doing is burning raw gas the bare minimum. go to Mikuni or Kei Hihn.com and they have complete diagrams of the carbs or you can call your local Honda shop and get a CLYMER manual for your bike. By the description you gave on your post it sounds to me like your carbs are getting flooded out?! They should have given you a float set gauge in the kits with detailed instructions on how to set the bowl float levels. Clymer manuals give you everything you need to know about your bike they cost round 40$ but trust me its worth it. Or it could be as simple as a vacuum leak. Check all of your vacuum hoses while the bike is idling. lil electical tape could help solve your problem. redneck it up
 
If it's been sitting since 2005 you'll need to REALLY clean those carbs. There's a bunch of tiny passages that gets clogged up over time from sitting with gas. The best way to clean those are to fully dissemble the carbs (they can still be in the rack of 4 though) and get them ultra sonic bathed with chemical bath.
That said, I'd put the a/f screws back to 3 turns out and then make sure everything else is up to par, such as compression, timing, ignition advance, valves etc. Only AFTER making sure all this is in order to specs, I'd get into the carbs - if it still doesn't run well.
 
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