Looking for some opinions on engine noise

on a XR250L RFVC engine. 8500 miles on it.

The engine runs good. It starts on the first kick. 60mpg but its not what
I would call fast.
It does blow a little blue smoke at high rpm. A puff or two. No smoking at
idle.

There is a tapping/knocking noise going on that's driving me crazy.I
adjusted the valves a number of times. They are in spec.

Yesterday while letting a friend ride the bike I noticed two things.First,
as the engine warms up the noise seems to lessen. 2nd, if you tilt the bike
while the engine is running the noise becomes intermittent, especially when
the bike is leaned to the left side (opposite the timing chain).

I've listened to the engine with a screwdriver pressed to the head. Its
hard to localize the noise but it appears to be in the top end somewhere.

My first thought was piston slap due to the fact that it goes away mostly
when the engine warms up (ie aluminum piston expanding when hot). But the
tilting thing makes me think timing chain.

Any Honda thumper experts out there mind giving me their two cents worth?

Thanks,

Roy

 

Check the alternator rotor bolt. If the rotor is loose and is walking
around on the end of the crankshaft, it has probably ruined the end of
the crank and itself...

Pull the clutch lever in with the engine running. Does the rattle stop?
It's a loose clutch basket. Take the clutch cover off and see if you
can move the clutch basket toward you. If you can, the big nut holding
it on is loose...

Check the cam chain tensioner and the tensioner spring to make sure
it's still hooked up...

Then there's the possibility that the counterbalancer is moving around
inside the cases...