(08-25-2018, 05:21 AM)peterbaron_imp Wrote: First time to hear this, even if engine was neglected should last longer, but you never know what went wrong (was there any oil consumption problem as well, you said??) during first owner possession???
Carbon build up bent some valves???, prior that should have/show some drivability problem, as carbon usually tends to build first around valve transition region and its stem??!!
I always use FI cleaner 1-3 year depending on mileage driven and top tier gas, usually 91.
Hope that dealer diagnose will correct issue, how about new valve seals and valves/seats grinding, checking valve guides = top end as well.
Diagnose it right and fix it at the first time (did they do a leak down and compression tests as well, was the head pulled off to see damage??). Do not intend to interfere with dealer diagnosis, as I do not have this vehicle in my hands.
Good luck and keep us in the loop

(08-25-2018, 05:34 AM)The ferret_imp Wrote: geez i find that hard to believe (not to say you are not telling the truth) but these motors have been super reliable for members of this forum. i mean the technology is 45 years old, and manufacturing materials and standards top shelf. we have one forum member with 100,000 miles, another with 85,000 miles, one with 65,000 miles and several near 50,000 miles without motor issues.

just out of curiosity were the valve clearances inspected at 8,000 miles on your bike?

(08-25-2018, 07:35 AM)max_imp Wrote: That is so unusual i have actually never heard of a situation like this, bent valve even.
even if it was overfilled with oil and burning some you would have had some white smoke for the amount of carbon, i putter around mostly and plugs are just perfect, just a small amount of carbon on the top of the pistons.

How many miles did you put on the bike and did the engine vibration start gradually?

Certainly would ask for the pistons and any other parts back to have a closer look.

Sounds like something went wrong and needs to put right, having said that i have seen somebody's car with engine problems, no fault codes and turned out the fuel was the problem, the tech took some out of the tank and spilled on the pavement, half of it never evaporated, it looked and smelled ok but........
new fuel solved the problem immediately, that was in new York as well and recently, never found out what was in the fuel but it makes you think.

Thanks for posting and best of luck; max

(08-25-2018, 07:44 AM)use2b_imp Wrote: pretty bike . other than the common 2nd gear problem with the Honda S65 in the 60's i have never had a single problem with any Honda i have ever owned in 50 years. sad it happened to you man and there must be a 3rd component to this somewhere .

(08-25-2018, 12:47 PM)Haystack_imp Wrote: Sorry to hear about your bike but, something's not right here...

Not to sound like a naive ignoramus, but could the dealer petition Honda Motor Co. to cover the cost of repairs since it's such a low mileage machine with no obvious evidence of neglect or abuse which may indicate a deficiency of materials and or workmanship?

I know of a Yamaha dealer several years ago who did this for a customer's 3 year-old machine and they covered the cost of parts (not labor) in the repair. His machine was out of warranty as well. The manufacturer may have information that has not been disseminated publicly. Wishful thinking?

Just a thought.

P.S. I'm closing in on 87,000 mi. and the motor's not been touched other than a valve check at 18,000 mi. which all were in spec.

(08-25-2018, 12:29 PM)Cormanus_imp Wrote: Geez, that sucks QUNITastic. I have nearly 60,000 miles on my 2011 and, other than routine maintenance and one valve adjustment, everything is tickety boo. This is certainly the first report like this I've seen on this forum. I hope you're able to find an explanation. I also hope you soon have the bike running smoothly again.