On the bench we have a still ugly set of carburetors with floats , needle valves and seats , with jets still installed . First things first . The hinge pin for the float has to come out . Don't hesitate , grab the micro torch the first time . I have turned several small C-clamps into tools to remove these occasionally obstinate items from their fragile supports but in most cases a small amount of heat from a micro torch or ha hot soldering iron will get them to move . Again , solidly supported use a pin pinch to attempt to get the pin to move . Some , not all , are easier to remove from one side so experiment tapping the pin back an forth gently until enough is exposed that you can grab it and pull it out . I can't emphasize enough just how fragile these posts that the pin is pressed into are .
All I can say about jet removal is fill the slot . I mean fill the flat blade screwdriver slot completely.
Some main jets are hex head but most are slotted . I have made screwdrivers from drill blanks for most common slots . These are not the common screwdriver shape but a blade shaped on the end of the drill stock with no taper . I want the flat of the diameter to rest on the upper surface of the jet and the blade to nearly touch the bottom of the slot . The handles are 1” aluminum or brass round stock and the shaft of the driver pressed into the handle . I want solid tools I can hit repeatedly with a small hammer while turning . Again start with heat first not as a last resort . Here is where I use a 50/50 mix of clean transmission fluid and acetone alternating with heat . Finally insert the bit into the jet . It should be sized so that it is between a slip and light press fit . While tapping the driver with a small ball peen hammer apply steady counter clockwise pressure . If the jet doesn't move with moderate pressure apply heat and 50/50 mix over a period of time . Patience is the key here . If the slot in the brass gives up it probably isn't your fault , some previous maniacal manic mechanic has probably destroyed the jet prior to your efforts . At this point all you can do is resort to a careful drilling and extractor . If you don't understand this part find someone who does .
All to often the novice will attempt to make up for other causes of flooding by bending the tab down onto the needle valve so far that no fuel will leak but also no fuel will flow . A general rule of thumb is if when upside down and the float adjustment tab is just resting on the needle valve adjust so that the float arm is parallel with the float bowl to carb body parting line . This only works if the floats have not been previously mangled .
Soaked , heavy or soggy floats .
even Nitrile floats have their service limits and susceptibility to modern fuels and alcohol content . If a float is suspect place it in a jar with fuel and compare it with the other three or a known good float . The difference will be obvious .
Worn needle valve . Seems obvious , replace .
The damage from constant contact with a needle seat will show as a definite ring around the Nitrile rubber tip . This just won't work . However in most cases the best cleaning agent for even the most green and ugly needle valve is simply your fingers and a bit of mineral spirits . The problem with this repair is its only half of the sealing element .
Dirty , worn or damaged needle valve seat . Simple enough ,replace .
Simple yes but not always the cause . A needle valve seat can be brought back to life with a little ingenuity . Remove the needle valve and leave the seat in the carb body for now . Find a drill bit whose shank , not drill , just fits in the seat . Cut the shank off the drill and chuck it up in a drill motor . Go over to a grinding wheel and attempt to reproduce the angle of the needle valve Viton/Nitrile tip on the exposed end . Finish this pointed down onto the side of the wheel . The reason for this is we are building a make shift valve seat cutter and using the grind marks as cutting teeth . Turn the shank around and do the same to the other end only this time the angle should be around 15 to 20 degrees . Those of you that have ground valve seats get busy as I explain the rest . Take a q-Tip and a bit of scotchbrite and either by hand or in a well controlled cordless drill and clean the valve seat . By hand take a few turns with the 15 degree end of the shank in the seat and observe the results . If you can see a definite bright ring all the way around the seat you're done . If more work is needed it may help to stick a bit of fuel line over the shank and use that to turn the shank . If that doesn't work by all means get out the fine valve grinding compound and use the drill motor . The seat was wasted anyway all you can do now is waste time . Do the same with the other end of the shank and attempt to establish the seat . This takes very little pressure and happens usually very quickly . Problem is after all this you may still have the problem and the needle and seat despite initial observations were not the cause .
The often over looked needle valve seat O-ring . Ignore this if your needle valve seat screws into the carburetor body . Oh this one still gets me on occasion even though I have the McMasters part # written on the toolbox (this for most BS34's )
Buna-N Shore A: 70 -35° to +250°F 9262K627 $2.94 per Pack of 100
Viton® Fluoroelastomer Shore A: 75 -40° to +400°F 9263K565 4.26 per Pack of 25
Sorry BTK in particular and Kawasaki in general but when I can get them at these prices you can not compete .
When you can undo the needle valve seat retaining screw and plate and the seat falls out it's pretty obvious that the fuel isn't getting past your needle and seat . It's going around the seat . Replace the O-rings and be happy . Don't cut them on installation , use a bit of grease and they should press in firmly . Verify that this is your dimension and install away .
Testing your repair .
After a carb clean of any kind I place an auxiliary fuel source at least three feet over the carbs and tip , bump , vibrate , shake and last but not least reproduce their on the side stand angle for several hours under that fuel to verify that there are no further leaks or overflow . As little room as we get to install these things I know I don't want to do it twice .
If a clean idle can't be established with the idle mixture screws less than 3 3/4 turns out from seat go up a pilot size . Put another way , you should see lean misfire anywhere from 3/4 to 1 1/4 turns from seat and rich misfire no further out than 4 turns . The sweet spot ideally is between 1 3/4 to 2 3/4 turns . Once again for those of you under the influence of cleaning solvent vapors , midnight microwave mystery meat burritos , exhaust fumes and or liquid libation , please , PLEASE , adjust the valves first . All will be right with the world if you do and if you don't gawd almighty will kill a kitten .
~kop
I was sitting in a parking lot waiting for my sister to come out of an appointment and had nothing else better to do . I'll be more than happy to edit in response to any reasonable input .