Bonneville America Forums Forums Technical Forums General Tech very poor running

Hi guys. My bike has never run worse. My plugs are fowling up. Major [not sure what you call it] backfiring up through the air- breather and some backfiring out the pipes. The bike starts but won’t rev up much as I am going down the road without these issues. I cleaned the carbs [jets] made sure my battery connections were tight and checked for air leaks. When it runs it smells very rich and actually is spitting out fuel out the pipes. I am very frustrated to say the least.

Easy things first; hook up some clear line to the float bowl drain & run it up the side of the carb body with the bike upright; do this for both carbs. Where is the fuel level of each carb?

Hey Willy,
Did some mice make a nest in your airbox?
Uncle Charlie

Willy,

You appear to be running way too rich. This could be caused by two reasons. Something has plugged your intake as unclecharlie suggested restricting airflow or you pickup up some crud and your floats are too high due to one or both needle valves sticking. Kens suggestion to stick clear tubing to the float bowl drain and place the tube beside the carb is a good one. The fuel should show up in the tube at just below the top of the bowl. Higher and the bike will flood.

Did you do anything recently to the bike? Change anything or add any items?

Good morning guys, I am running tors with 2 baffles removed with drilled out air box. Running 135 mains but trying to correct this I put 130's in with no change. No other changes. Air box is supper clean. I checked my float levels and both are .10 or close to 1/8" above the bowl separation crease from carburetor body. So is this the problem then?

I doubt it, although you can adjust that for a lower volume when you pull the carbs and verify that the enrichener isn't sticking open and that everything is in the proper place. What specifically did you do to the airbox?

Cut a hole in the bottom of the Uni filter. But this was a great while back and it ran fine then.

After double checking fuel levels, the right carb fuel level is level with the top of the bowl. The left is above as mentioned earlier. I did notice one thing now that I remember, after draining and taking the right bowl off I lifted the float and more fuel came out.

Check to see if your slides aren't sticking. Might be stuck in the up position allowing too much fuel.

The fuel enrichener might also be the culprit but I've left mine on before with no ill effects other than lousy fuel mileage. I'm running 135 mains also with no problems.

You might want to adjust that higher float. Make sure your main and pilot jets haven't come loose also.

So I guess I will have to take the carbs off to take a good look and clean them up.

The slides can be inspected from the top by pulling the chrome cap (4 screws) then removing the diaphram and slide. The needle is in the slide. It should slide freely in the housing.

Given the problem you seem to be having, it wouldn't hurt to pull the carbs and check/adjust things closely.

If there is raw fuel sputtering out the pipes then something is waaaay wrong...

At this point it would be helpful to know the pilot jet size and confirm that the pilot screws & related hardware (washers/springs/o-rings) are properly installed.

How many turns out on the pilots?

Are both mains installed properly?

Slide diaphrams seated properly?

How many miles on the bike?

Did this happen all at once or gradually over time?

pilots 3.5
mains are good.
Bike has 25000 KM and this issue did happen over time but got progressively worse all of a sudden. My bike has always smelled like fumes.


I took out the slides and they were a bit dirty/black so I cleaned them up. The diaphragms were seated ok but there was some dirt underneath them so I cleaned out that groove where they seat. I took the bike out for a ride and it gave out a couple of backfires/missfires but than all of a sudden ran fine. I am not sure what I did with your help to fix it but seems ok for now. We will see. I have to put air breather back in yet and some covers.

Hope you have things sorted out, Willy!

At 3.5 the pilot screws are pretty far out; try setting them at 2 turns out & see if things improve.

If that helps, without off-idle hesitation, then try 1.5 turns out & see if things continue to improve.

Let us know how it goes.

And run some Sea-Foam thru it.
Uncle Charlie