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i am currently checking valve clearance on 2013 sxf 250 with 70 hrs. bike was bought new and never been apart(as far as i know). when setting TDC the notch on the crank when it is aligned to the whole, has the cam gear marks intake totally up and exhaust totally down. are these the wrong marks to look at or am i missing something. bike does run just a little difficult to start.

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i had same issue a couple of years ago and watched a lot of youtube and talked to a bunch of people to figure out if i had top dead centre correctly.  i spun the cam's many times and never could get marks set right.  my bike is a 2012 250xcf, not sure how similar it is to yours as i've found different models and years don't look alike when you crack the motor open.

i finally found top dead centre after doing the following.  i took spark plug out and put a long screw driver down opening.  i spun crank until piston pushed the screwdriver to it's highest point.  For a 4 stroke, this will have 2 high points, one is top dead centre and the other is bottom dead centre.  The difference will be the check bolt at bottom of motor.  Take it out and remove washer and screw back in.  if it goes all the way in, you've found top dead centre.  If it doesn't, then spin crank to highest point again, and try bolt again; it should go right into slot in crank and lock crank in position.

After doing that, i noticed that markings matched up.

Your skills may be beyond mine, but that was the first time i completed that job and took me almost 2 weeks of questions before i had it right.  I'll be quick next time i check my valve clearances.

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TDC is piston all the way up

BDC is piston all the way down.

You align the cam lobes for adjusting the shims, which is lobes facing out. Now search for the TDC mark.

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