I have a 94 fatboy with a keihin CV 27206-93 that is running so rich that the oil smells like fuel and your eyes tear.Has run like this for the last 8 months but has recently gotten worse.Went to the gas station and I topped off the tank and when I restarted it barely made it home chugging, spitting, farting and popping while smelling real rich.Drained the tank new plugs and it went about 5 miles before fouling out the plugs again.

The bike is running a thunderheader with a screaming eagle ignition.The carb has a 165 main jet and I believe a 42 slow jet.The float has been reset at 12 mm.I have gone through the carb and cleaned what I believe was every orifice that is I there.I also bought a carb rebuild kit including accelerator pump, vacuum piston (which I did not drill) and a yost air screw.The float pin would not come out so to check operation I floated it in a clear bucket, and then attached the fuel line and shut off the fuel by manually raising the float.
Reinstalled and seem to run a little better, not perfect, but after about 10 miles it fouled another set of new plugs.I took the carb off my 93 sporty 883 which is running a 170 main with a 45 slow jet and installed it on the fatboy that now runs well. I have now transferred the problem to the sporty with the fatboy carb, so I know the issue is with the carb.
Recap:
Bike runs real rich
165 main jet
42 slow jet
Float set at 12 mm
Yost air screw can be turned all the way in and the bike still runs.
Any ideas would be greatly appreciated.
Ron

 

Hi from the UK and welcome to HDF.

If the float is set correctly then a likely candidate is the accelerator pump. Fuel is getting into the engine in an uncontrolled manner, as your carb swap has demonstrated. I recommend you call into the Evo section, where you should get more help. It is fixable and our experts over there should be able to sort it!

 

you state the "float pin would not come out"


I think you have the problem .
if the float cannot move freely , then you will have a float needle that will not shut off.


How did you replace the float needle if the float pin wouldn't come out ?.

 

I have the float set at 12mm as of right now. Any idea how much I can lower it in the carb bowl to try and lower the fuel level and lean it out? Maybe 14 to 16mm as that would cut the fuel off sooner?


Other than accelerator pump or low speed jet any other idea how it would be getting in? A crack in the carb housing?


Sounds a little hack I agree but it is on my sporty now which is a bike I run 3 miles to the beach and not have to worry about rusting chrome.








As far as the float and pin Is should have given a better description. The pin was stuck in both sides of the aluminum carb base, hammer and punch would not free it. However, the float was smooth as silk as far as operation. I cleaned the needle and seat with carb clean then attached the fuel line with the carb base off so I could manually move the float up and down to turn off the fuel. To test that the float was not cracked I had the carb bowl off and lowered the carb into the water bucket and watched the float react in the water and worked as it should.


I will run this over to the other section as you mentioned.

 

I don't think the solution is to adjust float level. There is another problem causing this, which needs sorting out. Your carb worked properly in the past with the correct fuel level and will work again, once it is back in rude health.

As I said earlier, post again in the Evo section, there are more expert members over there than in this section.

 

Going off memory, but shouldn't the float height be 11 mm? Another good rule of thumb is when holding the carb so the float will hand down (we will call your stuck pin a hinge) so the hinge is up pointing at the sky and the free end of the float hangs down pointing at the ground. If anything, at 12, you should be running lean.

Stock emulsion tube and jets? Dyno jet emulsion tubes and jets are waaay rich. Their numbers (sizes) don't match oem numbers

But anyways a quick a dirty is the bottom edge of the float should be parallel with the carb body gasket (o-ring) surface).

To get the pin out, have you tried heat? In a small area like that, use a soldering iron to heat the pin area up. Figure out a way to keep the tip of the soldering iron on the spot where the pin is pushed into the pin recess. Leave that on there for a while and let it get good and hot then remove soldering iron, a quick shot of penetrating oil, then repeat. The soldering iron confines the heat to a small area and is not too hot to melt the casting. Let it cook then blast with pen oil, then repeat. Might need to file or blunt the tip of the soldering iron for better contact.

What your doing is expanding and contracting the metal. Do some cycles of heat and cool with pen oil. Just pay attention to the arrow cast in the carb body near the pin. That tells the direction of removal.

Below link is a good write up on float level. I think your float needle is messed up or your missing something simple. Does the little spring tip on the float needle still work (or compress for that matter)? YD

 

That float hinge pin is directional/tapered.Look and see if there is not an arrow embossed around that area.It drives out in that direction.Float level should be about 1/4"- not compressing the buffer spring (if equipped).80" evo w/exhaust and or intake mods. should be running 45-48 slow jet,180-185 main jet (what I run in my 80"er for 7 years 30,000+ miles).You are able to run with air screw in because it's flooding.....

 

Sorry I was out for the last few days. Wife and daughter were home from work/school for Thanksgiving and had me knocking off the honey doo list, so I have not touched anything since.


Thank you for the tip on the soldering iron I will give it a shot.


I tried the pin both ways and was equally hard, but with the update on arrow I will put more emphasis on that direction.


I will re-jet using your numbers on the fatboy where they are working well for you with 30,000 miles.


Thank you for the help so far and I will touch base after I get her down again.


Ron

 

The pin requires a very small pin punch to drive it out in the direction of the arrow.You really don't need to drive it all the way out-only enough to remove the float.

 

Did you do something 8 months ago that might have started this problem? Or did it just start to run like crap?

If you rebuilt the carb or changed jets, it sounds like the needle jet is in upside down.