I exepirenced mechanical power loss while riding the other day. I was going about 80mph and didnt notice anything, but then had to slow down and then reaccelerate. WhenI began to speed back up I noticed a significant power loss and also a " throaty" sound from the engine. No misfires or stalling. I continused to runand got me home. Iordered a new set of ngk plugs, and am installing them today. Any ideasbout anything elseI should look into.

 

Make sure you have enough oil in it. Make sure it's not overheating, pistons expanding in cylinder. possibly jetted incorrectly? how warm is it by you?

 

You might also want to check your air filter & make sure nothing got jammed in the hole for the intake

 

My first thougts were fuel/air as well. I know it's stupid, but how's your gas level? And if you had just filled up, maybe you got some **** gas. Could be gummed up.