I pulled my bike out of storage and took it down to the shop for service prior to riding it for the first time this spring. The bike seemed to be running fine right out of storage and down to the shop for service. While I had it in the shop they flushed and replaced the brake fluid, changed the oil and air filters, changed the final drive fluid and coolant, and did a general bike inspection. Now the problem begins.... After I took it home I started to notice that it was lacking power during acceleration and almost seemed to wind out near the top of the RPMs, almost like a slipping clutch, if you’re familiar with that on a car. Well, I thought it just might be bad gas or something, so I just let it sit for 2 months before I decided to tackle it again. I rode it for the first time in 2 months the other day and it is far worse now. The bike won´t do over 70 MPH, and has to work hard to get there. I also hear a slight whistling noise with the throttle wide open. Could this be a blown head gasket? Is there anything else it could be? At idle I also hear a little bit of racket coming from the valve train, which wasn’t there when I took it out of storage. I´m avoiding taking it to the shop because I can´t afford an engine rebuild. Is there anything the shop could have done to cause this when I took it in for service? Any help or advice would be greatly appreciated! Thanks in advance.