Hi guys, Im new here so if this is in the wrong section i apologise. I wanted to make a thread on a really great friend of mines 2013 ktm 500 exc. Unfortunately he had an accident riding in the Northern Territory, Australia and passed on the 20/10/13 after a week long coma, RIP 'AZZA'. He had this bike for maybe 4-5 months brand new. I inherited his 500 from his mother who did not want it and said she would like me to have it. I was honoured. Thinking the bike would be a right off but thought it would be a great project, found that there was little damage. Couple scratches down the right side of the six days plastics and scratched akro slip on. A friend and myself went over the bike to find any problems. Twisted forks which was resurrected as soon as we loosened the clamps, found out for myself that the suspension was not set up properly for his weight as the power parts bashplate welds were split all the way so we put it down to casing out hard. His mother had a lot of photos and videos that he had taken of different aftermarket parts that were going to go on the 500, so i thought it would only be right to spend the $$$ on the bike how he would've wanted it. After going over thinking we'd found all the problems, came the task of finding and spending $$$ and waiting for parts to arrive. At this stage i had only started the bike and rode it up and down the street maybe 5 mins. All the parts i could afford had rolled up, so i started the process of removing the old and in with the new. All done and ready to ride, fired her up and took it slow. Found a nice little dirt track to open her up, got to 3/4 throttle and held on but there was nothing she was just gutless. My old Yami wr 400 would have ran rings around it. Tried a few times, headed home. Sat in the shed scratching my head. After searching forums, youtube and asking everybody that knew about bikes about this problem, everyone pointed towards the injector and or fuel. Azza had already payed for the emissions kit to be pulled off, I even double checked there work. So I cleaned the injector, changed the micron filters, changed the fuel sock and fresh fuel, try again to no avail, it just felt like it was starving for fuel everytime i twisted the throttle and this was every gear. I gave up for a while thinking i was going to have to take it in to someone. I got the bug again to find out for myself what it could possilby be. I scoured the net reading everything about this model, and was also fixing little things like the stupid kick stand and airbox cover, overall just general improvements. Then to my shock yesterday I come across a Thumper talk thread that Azza had made just months before he passed with the exact problem I had found with the 500. KTMPETE tried to help him but unfortunately it didnt work as the problem was still there so thanks anyway KTMPETE. After reading more on another thread some people said they had the same problem and that they had their mapping changed or got a jd jetting efi tuner and also removing emissions kit fixed it. $300 for this product i thought no worries, just as i was about to purchase, I found another thread stating that a 2013 ktm 350 exc had exactly the same problem and the bloke found the airbox had a restrictor in it. I thought no way could it be so simple, could it be the same for the 500, I had read 1000+ posts on the 500 and no one had ever mentioned this and there were many people pissed off that they had the same problem. So today I thought what the hell i'll give it a look, ran to the shed and ripped the airbox cover off and pulled the air filter off and stuck my head in, and there it was. I took to the bike like an Impatient kid on xmas day. Undone the subframe, lifted the subframe so the airbox and throttle body disconnected and out it fell. After putting her back together i gear up and head out.Thank the dirt bike gods!!! it was fixed it ran like an angry beast, it was a sweet and sour feeling I had knowing I had finally fixed Azzas pride and joy. But also knowing that he had the bike for months and never had the chance of really knowing the 500's full potential saddened me. So to anyone out there with the problem of twisting the throttle and the bike feeling like it is bogging out after 3/4 throttle or it feels you have no power, before you spend any cash take a look in your airbox for the restrictor, takes 5 secs to spot. If you can see the throttle body from inside your airbox then it has been removed. Also added a couple pics I hope this helps anyone that has the same problem as myself. Did anyone else run into a similar problem???