Re: drill jets?
I figured you go bigger because i was told to drill the low speed jets out.to stop the bogging..
You figured correctly. The slow speed jets on that 1973 65hp model meter fuel, not air, so to richen the fuel flow, the inside diameter would need to be larger. Also the jets (any fixed jet) needs to be seated tight, otherwise there would be leakage around the outside diameter of it which would be defeating the purpose of the jet.
You state in your first post "After cleaning and rebuilding carbs on 1973 65 hp johnson,it still stalls sometimes at throttle up."
If a engine is running slightly lean, normally it will have a habit of spitting back, sort of a hiccup, a hesitation for a fraction of a second that sounds like one of the carburetors has something being fired out the front of it. This may ocurr quite a few times before the engine actually stops. Is this what you're experiencing, and if not, describe exactly what is happening. Possibly, at an idle, the engine simply slows down and stops?
Regardless of the problem, we need to know if you have the proper compression and ignition/spark to begin with. What are the psi compression readings of each individual cylinder?
The spark plugs should be Champion QL77JC4 plugs gapped at either the original recommended gap of .040 or the revised 1990s recommended gap of .030 . One gap or the other may provide improved performance. What plug are you using... and do they all look alike after running? If different in appearance... describe.
With the spark plugs removed, the spark should jump a 7/16" gap on that model with a strong blue lightning like flame... a real SNAP! Does it? If not, what do you have? NOTE... the 7/16" gap is important... checking spark by using the spark plugs is a waste of time!
(Spark Tester - Home Made)
(J. Reeves)
You can use a medium size philips screwdriver inserted into the spark plug boot spring connector, then hold the screwdriver shank approximately 7/16" away from the block to check the spark or build the following:
A spark tester can be made with a piece of 1x4 or 1x6, drive a few finishing nails through it, then bend the pointed ends at a right angle. You can then adjust the gap by simply twisting the nail(s). Solder a spark plug wire to one which you can connect to the spark plug boots, and a ground wire of some kind to the other to connect to the powerhead somewhere. Use small alligator clips on the other end of the wires to connect to ground and to the spark plug connector that exists inside of the rubber plug boot.
Using the above, one could easily build a spark tester whereas they could connect 2, 4, 6, or 8 cylinders all at one time. The ground nail being straight up, the others being bent, aimed at the ground nail. A typical 4 cylinder tester follows:
..........X1..........X2
.................X..(grd)
..........X3..........X4
If all is as it should be (compression/spark), you can determine which carburetor ,ight be at fault by having the engine running with the carburetor face plate removed.... then insert two (2) fingers into a carburetor throat, acting as a manual choke of sorts. When you come across the carburetor whereas that procedure results in having the engine smooth out somewhat, you've found the offending carburetor.
Let us know what you find, especially with the compression and spark test.
