2004 yfz450 carb trouble

Let me start out to say hello to everyone, I found this website through a google search and it seems like there are some very smart people on here that might be able to help me with my problem.  I just bought a 04 yfz450, It has a Sparks pipe and header, pro design k&n filter, aftermarket rev box (no name) and that is all i am sure of at this point, as it was all on when i bought it.  I am having a very hard time getting it started, to get it to start I have to pump the throttle repeatdly about 7-10 times before it will fire up, at this point it will not idle at all, let off and it will die. When it is just over the idle speed it makes a very loud popping noise and will shot a 3 inch flame out of the exhaust.  I have taken the carb apart and cleaned it up with carb cleaner/air and found nothing dirty/wrong what so ever.  I have put in fresh gas, a new k&n filter, a new cr8e spark plug, nothing is fixing it.  It has a 175 main jet, 50 pilot, NCQV needle on 4th clip and air fuel screw 2.5 out.  I have tried the air fuel scre at 1/4 turn increaments from about 3.5 to 1 turn out and no change.  I live in western ks so elevation is not terrible high. I have not been able to ride bike yet because of this problem and am getting anxious to be back on a quad.  I have owned several banshees, and raptors but nothing has fought me like this one is.  Any help will be very much appreciated.   thanks jeremy  

Try to get it started then check the spark plug and see if it is wet or dry. I have an idea on it but would like to see if the plug is wet or dry.  

The plug is dry, I have the gap set at about .035.  I wired around the TORS switch but did not seem to help.  

Try putting a little fuel in the cylinder and try cranking. Don't pump the throttle when trying to crank. Let me know if it tries to crank or not and if backfire/afterfire is present.  

put a little fuel in it, it cranked over fine but still did not want to start, after 10 seconds of it cranking i pumped the throttle 3-4 times and it fired up.  still had the same back fire/low speed decel pop as always.  thanks jeremy  

Do you have a compression tester?  

I do but when i tried to take the compression test it seemed to push the compression out of the release hole and would not build in the guage.  How much compression should one of these motors have?  I am new to the yfz world and getting beat up by this little gremlin.   thanks jeremy  

If you put in around a teaspoon of fuel in the cylinder and have a good spark. It should have at least tried to start. I'm thinking you may have a partially sticking valve. I would also check valve cleareances. I'm not really sure on the compression for this model.  

When i had the carb pulled apart this last time i noticed that the slide is a little loose. I pulled it out and the O-ring that is in between the slide and the plate is starting to grow and not fit in the plate like it should, i don't know how big of a deal this is?  I am going to order a new o-ring from the dealer for it at any rate.  Does any body know how to set the idle on this yzf?  the only way that i can see to do it is with the actual cable where it goes thru the carb body and the thumb throttle housing but this does not seem right at all.  

Anyone have any ideas on what else I can check on the bike?? I am running out of ideas and places to look, I am guessing it is going to be a small problem like always that i have overlooked, Thanks for your help   Jeremy