help,, 86 fz600 carb ploblem

[larry lindenberg]

I have a 86 fz600 that idles fine and if you open it way up revs ok but it is getting to much fuel(BLACK SMOKE). if you try to accelerate normally it chugs pretty bad. i checked the compression and its about 150 straight across. I took the carbs apart 2 times and cleaned with carb cleaner then the 3rd time I boiled them out with lemon juice,,, they look super clean but im still having the same problem,,, chugs when accelerating and black smoke( im guessing to much fuel) when accelerating fast,,, but when it accelates fast there isnt the chugging

 

[ChevyFazer]

I would be looking at the jets, the way your describing it it sounds like its running way rich. So find out what the stock jets should be and find out what's in there.

 

[mayassa]

Pick up some sea foam and run it through with a tank it will soften and dislodge any thing blocking the jets. Any auto parts store carries it.

 

[fb40dash5]

Might need to set/replace your float level and needle valve. My old XJ was sorta like that when I bought it- ran really rich, though it ran OK. I set the float levels correctly, and it took me FOREVER to get it running right again, turns out the float levels were so high it had been running on the fuel spilling up out of the bowl, and I guess someone had tried to adjust for it.

I dunno what kind of carbs it has to tell you more on adjusting levels.

 

[ChevyFazer]

Might need to set/replace your float level and needle valve. My old XJ was sorta like that when I bought it- ran really rich, though it ran OK. I set the float levels correctly, and it took me FOREVER to get it running right again, turns out the float levels were so high it had been running on the fuel spilling up out of the bowl, and I guess someone had tried to adjust for it.

I dunno what kind of carbs it has to tell you more on adjusting levels.

That's also a real good possibility.

 

[ChevyFazer]

Pick up some sea foam and run it through with a tank it will soften and dislodge any thing blocking the jets. Any auto parts store carries it.

If something was blocking or clogging the jets it shouldn't be running rich, I should be leaning out out on the top.

 

[larry lindenberg]

well after going thru the carbs again and looking at a carb parts breakdown i find that all four carbs are missing parts,,, there is a rubber piece that goes on the needle and it has a little tit that drops down into a small hole in the bottom of the needle housing that is gone,,, dont know if thats part of the problem or not

 

[ChevyFazer]

If its as you described then more then likely that is your issue, and since those rubber pieces are gone its allowing more fuel to flow vs being regulated

 

[fb40dash5]

If its as you described then more then likely that is your issue, and since those rubber pieces are gone its allowing more fuel to flow vs being regulated

Those are what makes the float needle seal, and yeah, they're kinda important.

Without them, the bowl will overflow, either out a vent tube, or through the main jet tube and into the throat, where it will make your engine run stupid rich. Or hydrolock a cylinder and bend a rod, if you've got a powerful enough starter.

Take the time to read up and wet-set the float levels. It's a pain, but not as much as pulling the carbs a 4th time to do it anyway. IIRC (and you have the same style Mikuni carbs mine had) the proper level was about 4mm below the bowl seal, meaning basically level with the bottom of the bowl's mounting flange. Using rubbing alcohol or something less nasty than gasoline makes it much cleaner when you have to drain the bowls repeatedly to get each level correct.

 

[TownsendsFJR1300]

A quick way without dissassembly to check the float level:

If you hook up a clear line to the drain nipple on the bottom of the float blowl (one at a time), tie the clear line upwards. Now open the fuel valve and turn open the float drain screw. The fuel level for that carb will now show in the tube. Generally, it should be pretty much just below the mating surface of the bowl and the carb body.

As you noted above, if your missing parts, get those straightened out first. Also, not mentioned, check you floats themselves and make sure their not leaking (either fluid inside or hold under water and check for bubbles). If their leaking, the float will stay open ALL THE TIME, and thus run rich...