Hey all. 91 FXR. 2" drag pipes, no baffles, CV carb with 46/185 jets / CVP kit.

When I got the bike it had a size 50 idle jet and was running too rich. I then put baffles in which made it run even richer. I couldn't even leave the air intake filter on.

I got some CVP goodies and rebuilt the carb with a 46 idle jet. Baffles on at this point. It ran great but my idle mixture screw was set way rich and it idled high even with the idle set screw all the way out.

I removed my baffles as they sounded terrible. The bike ran really well that day and I couldn't believe the increase in power I was feeling. The idle mix was still fairly rich.

I sorted out the mix screw and then had full range of adjustment.

Now the bike runs like total crap until it has heated up really, really well. It backfires out the pipes with a loss in power, totally bogged. It feels kind of flooded at that point.

When it has warmed up really well then it runs like a top. I can set my idle low and take off like a bat out of hell.

FWIW the only thing I didn't remove and clean was the choke cable / plunger as I didn't know what I was dealing with at the time.

What are some things that could cause these symptoms?

Am I correct in thinking that an intake leak would have the bike running lean and cough out the carb?

Would an exhaust leak cause this? Maybe the expansion of metals causes a leak to close.

Would a stuck enricher plunger do this too?

What happens when the bike warms up that causes conditions to change?

I'm just trying to understand all the details here, that should help me deal with this once and for all.

Thanks.

 

Sounds like it may be running lean when cold.

 

My guess is an intake leak.

 

It'spossible that you have 2 symptoms. Intake leak and drag pipes....maybe this video will help...

 

Yes, I've seen that video before. I understand drag pipes take a hit on low and mid range torque. However they were on the bike when I bought it and can't afford to throw another $1k at some 2 into 1's.

 

Good video.

 

Do the intake o rings before you go any further. Those damn things can leak/ not leak. Leak a little. I change em ever other year. Try to find the blue one. They seem to last longer. Intake leak will screw with everything your doing. Good luck

 

Setting the idle too low can cause off idle running problems also and some popping thru exhaust when letting off. Just throw some shorty mufflers on it for the time being.

 

Thanks guys, I did check for intake leak earlier yesterday with propane and found no change in idle.

I do however have a new set of intake gasket rings that came with my CVP rebuild kit. Perhaps I'll swap them in and see if there's any difference.

 

You have to spray some carb cleaner or something similar at manifold and watch for a puff of smoke at exhaust as it will leak and not have an idle change.