Valve clearance information

The most common setting for those engines is 0.14mm for Both valves.

Approx 43.4249 ft-lb

http://www.ataq.qc.ca/hosted/Honda_ELEMENT_Valve_Clearance_Adjustement.pdf

Valve adjustment is not a simple task, the valve clearances will need "shimming" these are thin pieces of metal to take up the gap or slack between valve and rocker arm. You will need service manual and some feeler gauges, and purchase a set of shims

for adjusting the valves look for a sticker under the hood with valve clearance specs or a service manual.You will need appropriate feeler gauges and a 10mm wrench and a flat tip screw driver.If the car is a 4cylinder the cam gear will have 4 notches on it they represent watch cylinder to adjust if it is a six cylinder the front cam will have notches on it with numbers on it you adjust the valves of the cylinder number that is lined up with the timing marks.I recommend using a vernier caliper and setting it to the correct clearance that the valves are supposed to be set to and drag the feeler gauge through it so you can get use to what the correct clearance feels like on the feeler gauge.If you have never done this I would take it to a good shop because this does take some skill and drivability problems can occur if done incorrectly.Good Luck!

Sometimes a dirty oil filter will cause lack of oil to the top end at startup.
As soon as the oil warms, it flows better and faster and hence the noise goes away after warm up.

If you need valves adjusted, the motor must be at TDC on compression stroke(both valves closed)
The motor must be cold do not try to adjust the valve clearance on a warm engine.

On TDC, pull the valve covers and check the clearance on the intake and exhaust valves by inserting a feeler gauge under the tappet.
INTAKE should be : .03-05mm
EXHAUST should be .05-.08 mm

Im sure you don't need a valve adjustment. but if you do: Put Engine on TDC
Loosen the locknut with a 9 or 10 mm wrench, stick the feeler gauge under the tappet, and tighten the little square tipped valve adjuster screw clockwise until you feel friction on the feeler guage.
Enough friction that the feeler gauge feels tight but you can still slide it back and forth.
Not carefully tighten the locknut. Check the feeler guage during tightening to make sure it didn't get too tight or too loose. Once you set the clearance, move to the next valve, and repeat the process using the other feeler guage.
Once both are done put the covers back on and your done,

NOTE: You may have to remove seat, gas tank, airbox, and side covers to get to the covers.

http://faq.ninja250.org/wiki/What_is_the_adjustment_procedure%3F

You adjusted the valves too tight. Back off of the adjustment before you break parts. You Have to set the rocker arm clearance when the engine is cold. (Not warm, not hot)

Use a feeler gauge.
The clearance for the Intake valves is .007 to .009. (7 to 9 thousandths)
The clearance for the Exhaust valves is .009 to .011 (9 to 11 thousandths)
You want a slight drag when you pull the feeler gauge through. This technique takes a certain amount of 'Feel'.

Intake valves are to the rear of the bike and should be adjusted between 0.005" and 0.007". Either is acceptable. Exhaust valves are to the front and should be 0.007" and 0.009".

They're not tappets--you can adjust them with a wrench and a set of feeler gauges. Here are the clearance measurment numbers for intake and exhaust:

• 0.08mm - 0.13mm for the intake valve clearance
• 0.11mm - 0.16mm for the exhaust valve clearance

There is much more helpful information on this web page:

http://faq.ninja250.org/wiki/Engine

Click on the link "How do I adjust the valves?"

You will also find lots of valuable information on your GPX 250 (called a "Ninja 250" or "EX 250" in America) on this web site:

http://faq.ninja250.org/wiki/Main_Page

Good luck!