I am a new member here.   I'm in St. Louis (Elev 750ft). Thank you for providing this forum. I've already taken advantage of some of the modifications described here. I recently inherited a stock 2007 S40 with only 2300 miles on it.  Unfortunately it sat in a garage with gas in the tank for over four years.   So now I'm trying to bring it back to life.   Here is what I've done so far:

1. New battery.
2. New stock air filter.
3. New stock oil filter and oil change with 10w-40 synth.
4. Raptor petcock and fresh tank of high octane with a dab of sea foam.
5. Cleaned the carb.  However I am a novice at carburetor work. Also I could not get the top screws off the carb so I could not get to the top portion (I need to get an impact driver). I cleaned the rest with gum out and a toothbrush.  It did not look terribly filthy on the inside.
6. Seat raised 1" with #7 stoppers.  
7. Purchased a good condition HD Dyna muffler and clamp but I have not installed it yet.

So now,  here is what is going on with the bike:

1.  It will fire up and will run (I put about 50 miles on it last weekend). However I have to keep the throttle opened a little bit because it will die at idle.  I cranked down the idle screw as far as it will go. However there is still about a quarter to half inch, depending on how warm the bike is,  between the end of the screw and the point where the bike will die.   I drilled out the plug on the idle mix screw and I've been playing with different settings for the mixture but none of those seem to make a difference.  The bike still dies if I don't stay on the throttle.   So that's my issue 1.  Any suggestions?

2. The bike backfires like crazy (shocker!).  As before, tinkering with the idle mix screw does not seem to change it. I've ordered a new header gasket just in case the old one is somehow letting air in the pipe.  Also, I'm installing a dyna muffler.  Any other suggestions?     Also, with regard to the dyna install, the tech section suggests using a tin can to make the crush gasket.  Won't the tin rust pretty quickly?   Also, I bought some Permatex Ultra Copper Maximum Temperature RTV Silicone Gasket Maker that I plan to use at the joint and on the header gasket.  Do you see any problems with using this?

I'm guessing that some of you may say that both of my problems are still carburetor related, but I was hoping  I missed something or that there may be other easier fixes.  I really hate carb work  

Thanks again!

If the bike won't idle. Idle mix adjustment makes no difference at all. 1/4" of space between the idle screw and where the bike stalls, there is one thing to fix.  The pilot (idle) circuit in the carb is plugged up.
You're relying on the needle jet slightly opening to keep the bike running with a throttle position like that.  
Pull the pilot (idle) jet, very small wire through the hole...make sure it's clear.  Carb cleaner in the passages. Remove the mixture screw.  Blow out the passages with compressed air. Air should come out the idle mix screw hole.  Once you have air there, you need to get air coming out the small idle holes in the carb bore.  When air flows cleanly through the circuit, fuel should flow as well.

Oh, and welcome!  You've got a nice bike there.  Just take your time, learn as you go, and it will last a long time with you taking good care of it.

I don't believe the RTV will take the heat.
Don't put it on the header at all.  The gasket will do fine.
I believe steve is right, idle circuit is plugged.
Clean again.

Do back up the screws with a solid object if you're gonna use an impact hammer on them or you'll break off the tabs.  I would prefer to use vice grips on the head and replace with allen head screws.

So you raptorized, did you plug the vac port?

Carry one with you. When one of those caps starts leaking,,,

Steve and Versy have it exactly right.  Do what they suggested.  You can do the white spacer mod after you get the Dyna on and you can get a variety of pilot and main jet sizes to play with.  They're cheap, and I wouldn't just assume that the 152.5 will be right. The ones you don't need you can very easily sell or hang on to in case you move or need to tweak for another reason.

*I also agree that the RTV won't take the heat and don't see a need for it.

Steve H wrote on 09/02/15 at 15:07:25:


Steve, are these idle holes the 2 vents with the hoses attached?

Thanks, Scot.   Good to know.  Wildwood here.

The idle circuit outputs beyond the butterfly. Between the butterfly and the engine if I remember correctly.