2003 Honda BF90A Stalls at Throttle Up

JDusza

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Joined
Apr 21, 2009
Messages
977
Hi. I'm staring at a Honda BF90A, Serial BBBL-1G06752. 2003, I believe.
Bringing it back from the brink.
I have it starting and idling well, but, when I ask for throttle it dies right away, whether or not I put it in gear. If I add choke it will come back to life and increase smoothly. It will run well if I can get it more fuel. Seems like too much air and not enough fuel.
Across the 4 carbs, I've found the low speed needles are backed out from 4 to 7 turns.
Both fuel pumps are good. Squeezing primer ball makes no difference.
I tried spraying WD-40 around the intake manifold gasket and arounds the carburetor gaskets with no change in performance.
If I go after the carburetors with $50 rebuild kits, that'll be a couple hundred $$ without even knowing if the carburetors are my problem. My first thought is to remove the rack and do a general inspection of the low speed jets before I tear into anything.
Are there any other areas of air leaks that I should be looking at?
Thank you,
J
 

JDusza

Ensign
Joined
Apr 21, 2009
Messages
977
Bueller? Bueller?
Spark present on all 4 cylinders.
Compression: 200, 205, 200, 198 psi
I took the rack of carburetors off and am going through each one.
My question now: Should the Jet Set (parts list item 18) and the Main Nozzle (parts list item 20) be essentially a clear tube?
I've opened only 2 carburetors yet, but have found this tube blocked on both. If this is the main nozzle, shouldn't it be clear from bottom to top?
Any help is appreciated.
J
 

JDusza

Ensign
Joined
Apr 21, 2009
Messages
977
I called a dealer who advised the main nozzles should indeed be free and clear. I couldn't get a wire all the way through but a squirt of carburetor cleaner assures me the passages are clear. I also found another jet blocked on all 4 carburetors, inside the bowl adjacent to the main nozzle. Can't say what this jet is for but all 4 carburetors were blocked the same way. Cleaned them out.
Gonna put the rack back on and see what happens. Maybe it'll work
Thank you for the help. Appreciated. lol
J
 
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