Yamaha 1300 Tourer - Yamaha 1300 Tourer Fansite

I have an '07 1300T w/ 40k miles. Never had a lick of trouble, never been run low on oil. Have been noticing a noisy lifter type rattle/noise lately. Only when the engine is cold, and only for the first few minutes/miles. Specifically noticeable when decelerating through lower gears with clutch lever out. First garage said they didn't really notice anything, and it wasn't the valve train. Dealer says is sounds like piston slap. To confirm this diagnosis, a complete strip down is necessary. I can't find any other posts for this issue for this bike. Does anyone have any knowledge, experience, or other information on this subject? I love this bike, and at my age, was hoping this was my last bike. Even was thinking about tryking it. So, how bad is it? Thanks, Beejay.