Hi, My 82 sr250 which I bought in the spring of 2014, exploded that same year in the late autumn. What to do? I proceeded to look into how much it would cost to rebuild her and at the same time looked into finding another bike for less than a grand. I didnt find another bike, great I can do this, right? I found all the parts i needed for the rebuild at cheapcycleparts.com and took on the task. I have pics of all of the damage and parts that were affected but I dont know how to post these on this forum. I am a novice and I have never worked on a mbike before all of this happened. I have however changed brake shoes and cables and oil. That is it, not much experience, I know but i do have the factory service manual and whilst it may not be for the inexperienced and uneducated I figured, what the hell, I can do this. The parts that needed to be replaced were the piston, the camshaft, the valves and the cylinder head. Yes also the sparkplug and all of the gaskets. Oh yea the rocker arms too. I was fortunate to have been introduced to Jim Bauer from werks engineering and he rebored my cylinder and inspected the cyinder head I bought through ebay. All of the parts were installed by me with his guidance and after inspecting the clutch and trannny I was good to go. I had wanted to at this time change the airbox to an pod filter which I thought would be best for the bike. What do I know? Absolutely nothing!!! I start the bike and rode her for about five minutes and I get this backfiring along with a jerk and a serious lack of performance. I am told that this is because she is running lean so she needs more fuel. The bike still has the mikuni bs34 carburetor it was built with and the factory has it set to function proper with the airbox it came with. I replace the pod filter with the airbox and try again...still the same issue. I am riding her around the neighbourhood and I notice when i shift and accelerate she slows down then speeds up. Is this a carb issue, and why? It is the same exhaust and air filter , the sparkplug is new, the valves have the suggested clearance and the oil and fuel are new. do I need a new main jet? I am quite frustrated and yes I understand I am not an professional but do I need to bring her to a shop and spend minimum 100/hr for her to run proper? What am I not doing right? Thank you.