Right exhaust valve opens 2/3 rotation before left witha click


I just rebuilt my 2004 xr650r (new piston, cylinder, crankshaft, connecting rod) after doing 2500 km through the Libyan desert. I quit 2 days before the end of the trip due to serious oil burning and engine noise. Got sand in the engine, piston was a mess, etc. I replaced the mentioned parts and had Precision Concepts redue the head (new valves, grinding, etc.).

I have everthing back together and adjusted the valves. When I rotate the crankshaft counterclockwise to check the valve gap, the right exhaust valve opens 1/2 - 2/3 rotaion later than the left exhaust valve with a very slight clicking noise. The lifters looked ok before assembling. I don't get it!

Shouldn't they open simultaneously? And the slight click?

Thanks, Steve


Sorry, In the title I meant to say: Right exhaust valve opens 2/3 rotation "after" left with a click

It sounds like the auto decompressor . I think that is normal.

I've found 5 -6 postings related to thiss occurance on this site and others. Some think it is normal, others attribute it to a possible slight clockwise rotation of the crankshaft while finding TDC. I'm trying to figure out the functioning of the decompressor cam and the reverse deompressor cam and if they lead to the clicking and release of the right exhaust valve when approaching TDC.

At this point I just don't get it, the "clicking" sounds disturbing, and don't want to casue harm after rebuilding.

Thanks, Steve

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