i have an 03 600rr, im having an intermitent loss of power in the 5000-8000rpm range. the bike doesnt shut off, it feels like a surge. it can happen in any gear. it can happen in during city riding and highway. Maybe someone can help on this situation???

 

Have 05 Rancher 350 FM, just done a .40 bore over. Small rattle like possibly valves sticking or need adjusting???? Also loss of power mostly in full throttle. Just feels like a miss. Sounds like it may be an exhaust issue . I currently have a HMF performance muffler in pretty good shape. Any help would be appreciated. registery cleaner