Motorcycle Repair: Honda ATC 250 Cam Timing, honda atc 250, camshaft timing

Question
I am rebuilding this motor and I have no idea on how to set the cam timing, can you help me with this or do you know where I can get a schematic? Thank you for your help.

Answer
Hi Carolyn,

You did not mention the year of the ATC
so I will give you what info I can.
Most Hondas use a similar method for installing
the camshaft and timing it.

If you look at the marks on your
flywheel or rotor there should be an
"F" for setting ingition timing and a "T" for
the camshaft timing.

You align this "T" mark with the mark on
the engine case. At this point your
piston will be at the very top of the cylinder or "TDC"
(Top Dead Center)

The camshaft gear should have two marks
on it that you can align with the top
flat plane of the cylinder head.

***
Install the camshaft with the lobes facing
downward. Align the flywheel "T" mark and then
align the marks on the cam gear with the
flats of the cylinder head.
***
The gear bolts should go in, do one at a time,
tighten them each a little turning the engine if need be.
Watch the bolt heads are tightened enough so
they do not hit the cylinder head when turning the engine over.
You can do the final tightening after confirming the cam timing.

Sometimes the cam gear has two lines
across from each other or maybe dots.
They may be on the backside of the gear.

If done correctly the cam lobes
will be downward and the piston will
be at the top on the "T" mark and
the lines on the cam gear will align
with the head surface.

All these marks should stay in alignment
to prevent the valves from opening and hitting
the piston. Gently turn the engine backward
slightly and then move it forward to the
marks and double check that they are
aligned closely.

You may have to install the cam chain
tensioner and recheck the marks again.

Try turning the engine a few times by hand gently
to make sure nothing is hitting.

If you have any problems send me a follow up
question rather than do any damage.

Picture of cam gear:
http://www.dansmc.com/valve_timing_lines.jpg


Wayne S.
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