dohc top end rattle

[events]

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[LukeM]

We'll need a little more detail:  what year, is there oil, has it been changed lately, have you done any maintenance to it since you got it, chains tensioned, valves adjusted, carbs worked on/synchronized...

You said high rpm running...are we talking at or near redline? in all gears or just low or high ones?

Usually it's an oil supply issue, or lack of it, to a bearing or somesuch.  That's a first guess.  I'm sure others with better knowledge will chime in.

Luke M

[Re-run]

As luck suggested, top end noise can be from mis-adjusted valves. They are possibly too loose. Cam chain noise can also cause some top end rattle.
If you don't have it, get the manual and it will show you how to adjust the cam chain. From there, you can adjust the valves. You will probably need some shims.

Check oil level and if it has been a while since a change, it might be time again. When draining, check the oil for foreign material.