Our Carbon Footprint

Five years ago I bought a Yamaha "Super Tenere" adventure bike to leave behind here in Phoenix for my son to use, and for us to use while we're here during Winter. Until now the bike has given us 30,00 trouble-free miles and has been a pleasure to ride.
When our son went out to ride just before Christmas, the bike failed to start. The starter would spin the motor and the bike would cough as if a cylinder was firing now and then, but that was as close as it would come to running. Holidays approaching, we postponed taking the bike to the shop thinking they'd probably be working with a skeleton crew 'til after New Year's. Still, we delivered the bike to them on the 30th of December.

Nearly two weeks later we hadn't heard from them. We called.
"We'd like you to come see this!"
Uh-Oh.

In the shop, the bike looks like a bomb hit it...
Side covers off. Gas tank off. Air cleaner system off. Radiators (two of 'em) detached and laid off and out of the way. Both throttle bodies- ditto.
It looks sad.

But all this work exposes the intake system, and allows us to look at the intake valves.
And they are a MESS. There's a half inch of carbon caked around the stem, extending outward almost a quarter inch. An accumulation of gunk like this HAD to have had an effect on the gas/fuel mixture entering the bike's combustion chamber!
What would cause such a phenomenon?

"How do you ride this bike?"

My son has used to bike mostly to commute to/from work. He rides city streets 10 minutes to the freeway, then spends another 20 minutes riding 65+- mph there. At this speed the bike is turning about 2,000 RPM.
And there, apparently, is the problem-
He should be putting more stress on this engine!

Our parents used to talk about "blowing the engine out" now and then by taking the car onto the open road and "opening her up".
Turns out that's true.

And this is why it was a good idea for Granny to take her "Brand-new, shiny red, Super Stock Dodge" to the drags. (Thanks, Jan and Dean!)

And our behavior on the bike will have to change.