Motorcycle Repair: Sudden stoppage of xt550 1982 yamaha, yamaha owners, bit of power

Question
1982 xt550 - This quit on me while going 50 MPH or so - felt as if it lost a bit of power, bogged down a bit then quit.

I kick started it while still rolling, WOT'd it, a couple of times in 3rd gear, to ensure it was still solid vs. seizing...felt solid, but lacked full power.

It made some "clanking" sounds - I let it cool, started it, and can hear the same clanking - But it still starts, while popping and sputtering a bit. . .

I have adjusted the valves, and may need to revisit this as it's my first time doing so.

My question: Is there a common issue with these having top end issues?

I instantly thought: sucked a ring, or something bent in the valve assembly.

I have little experience with 4 stroke maintenance, but a lot with 2 strokes. (Rebuilt several, bored, etc. . .)

Any help you can offer is great.

I have the original Yamaha owners & Service manual.

Please advise if you have experience with this bike.

It has ~ 3-4K miles, mostly off road -

Answer
blaine,

its sounds like to me you have a bad valev or broke valve spring take off top end lookj at valve or run a compression test to see it it holds compressioin. then contact me again ,i will get you going i guarantee you,
p.s please leave feedback on my answer and you can also nominate if you choose to ok,

                              mitch kruszynsky