Stock 94 flstc with evo and cv carb.

Problem is the bike will idle with choke on, I can get it rev but it snaps and pops like hell. With the choke off a little will die IMMEDIATELY when given the smallest and I mean smallest amount of throttle. This says vacuum leak to me so I used carb cleaner and thought I found a leak, and installed new intake gaskets. I did it 3 times, then the 4th time I used high temp sealer, and was convinced that I had it sealed, same thing.

Squirting around with carb cleaner I cannot locate precisely were the leak is, but the idle will jump just cannot tell from where. For a while I thought my head gasket was leaking, though I was not able to recreate the idle jump the next day.

Other than the intake to the heads, and the intake to the carb, what are the other common places for leaks on these old dogs?

 

What led up to the problem? Running good one day and crappy the next? Just gradually got worse and worse? Bike been sitting for a long period of time? Did you just get it?

 

I have had the old girl for many years. It has been running a bit lean for a while but it was not bad enough to worry too much about it. The bike has sat for a while now, with only very light use over the last few years. last fall I finally got the bike up to Chicago after my move and I put a new battery in it and road her once, she ran great.

This spring i go to start her and I get a click click, battery tender was on all winter, but I charged it up, still a problem. (insert lots of pokin and testing) so I get done completely rewiring the bike, something long over due. (long story) go to fire it up and it started just fine, sounded great, when i got on the bike and backed out of the garage i gave it some gas and she snapped and popped and ran like crap. thought the bike was just cold so it nursed it down the street a bit, it did not get better.

got back to the garage and looked for vacuum leaks, and found one in the front intake. the story continues above.

 

ya, im stummped too.

 

Intake manifold gaskets.... time to replace them , J&P sells some blue ones with a lip on the inside , these have typically been my cure all... if that doesnt fix it , CARB REBUILD TIME !!!! woohoo... thats always fun!

 

With the choke on basically you're dumping raw fuel into the intake manifold. The same thing happens when you twist the throttle except that fuel comes from the accelerator pump. At idle the fuel comes up through the main jet. So that's what I'd check first as even the smallest piece of crud can gum it up. You may have an intake leak too but usually the motor will still idle (albeit poorly) unless it's a humungous hole somewhere.

 

I would check the pilot jet. If it gets blocked by debris it can act like that. A plugged/blocked pilot jet is a fairly common issue. It's a very small opening and gets plugged/blocked pretty easily.

At idle (and up to 1/4 throttle), fuel is supplied by the pilot jet, not the main jet. In reference to the pilot jet, your statement is correct.

 

+1 on carb issue, especially with the "sitting for quite a while". You may have varnish/gum blocking a jet or passage. Too much air or too little fuel will have essentially the same effect and it sounds like you've gotten rid of the too much air problem. Look for fuel starvation. Check in the gas tank too for a gooked up strainer and/or fuel valve.