So I just picked up a 87 250r and it starts right up and runs great it will rev out perfectly in neutral the only issue is when there's load on the bike it won't hit powerband. It will run good but powerband won't come on. It has a full exhaust with a k&n filter and no lid that's about it. I can't get it right it has a 48 pilot and a 152 main. Everything is fine I put new reeds in new coil and cleaned up the exhaust leaks so what could it be? Jetting?