Question about 2002 Yamaha YZ 426 F
Most motorcycle cam gears have a mark on one tooth, often just a punch mark, sometimes an "o". Usually this mark should be "straight up" in line with the cylinder when the engine is at top dead center on the compression stroke. Double-check your service manual to be sure for a particular bike.
So here's how you set it. Remove the flywheel cover and rotate the engine so that the piston is at top dead center. There should be a "TDC" or "T" mark on the flywheel, and some sort of corresponding mark or pointer on the engine case to line this up with. To make sure, remove the spark plug and verify with a flashlight that the piston is as high as it can be when the marks are lined up.
Now rotate the cam gear until the punch or "o" mark is at the very top of the engine (in line with the cylinder, if the cylinder is slanted). At this point, neither the intake nor the exhaust valves should be open.
Now connect the cam chain while both the crankshaft and the cam gear are in these reference positions, and you are done!
Posted on Nov 06, 2009
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Get Ford timing tool kit, part = otc-6488 (For about $119 USD on eBay)
4 timing chains (3 front including the optional balance shaft chain + 1 back)
2 cam guides (1 front + 1 back)
2 oil tensioners (1 front + 1 back)
1 jackshaft tensioner (1 front)
1 jackshaft guide/cassette (1 front)
1 balance shaft tensioner (1 front) (will probably be ok, so dont replace it)
1 balance shaft guide (1 front) (will probably be ok, so dont replace it)
new sprockets + bolts + gaskets etc.
new spark plugs + throttle body cleaner + lithium grease spray + oil change
of these parts (the front stuff) can be obtained as a primary timing
chain rattle noise kit Part# = 2u3e-6d256-** ab for 4*4 & bb for
The kits also have later part numbers for us$ 76 @ http://www.fordpartsonline.com
My parts order (without the balance shaft stuff) was:
$76.04 KIT-TENSIONER TIMING 2u3e-6d256-ab
$47.93 Engine, Camshaft and timing, Timing chain, TIMING CHAIN, Explorer, Mountaineer, Rear - 4.0L SOHC - 4.0L SOHC
$57.36 Engine, Camshaft and timing, Chain guide, CHAIN GUIDE, Explorer, Mountaineer, Jackshaft To Cam - 4.0L SOHC - 4.0L SOHC
$103.22 Engine, Overhaul gasket set, OVERHAUL GASKET SET, Explorer, Mountaineer, Upper (Valve Grind) - 4.0L SOHC - 4.0L SOHC
$28.93 Engine, Camshaft and timing, Tensioner, TENSIONER, Explorer, Mountaineer, Upper - 4.0L SOHC - 4.0L SOHC
worth mentioning that this procedure is not enjoyable at all and
should be undertaken with at least 8 full days to completion (I recon
you could do it in half the time the second time).
It is basically on entire engine re-build with both heads off and the engine out of the vehicle.
is not possible to do the rear chain or sprocket with the engine in
the car as the flywheel needs to come off + at least 1 head, but it is
possible to do the front primary chain and or front cam chain with the
engine in the car.
will be a ford exploder and timing expert after you do this - the main
reason should be the love of your American built vehicle. Its a solid
car - except for the plastic guides!
Note: This is how i successfully did the job, but i am not a ford
mechanic and don't hold me responsible if this does not work for you.
Small Sprocket on the crank turns a larger (2 to 1 ratio) jackshaft
sprocket that is in turn connected front & back to the 2 camshafts.
Thus a 360o turn of the crank will turn both the camshafts 180o.
Firing order is 1-4 2-5 3-6, Right side numbers 1,2,3. Left Side = 4,5,6.
At TDC pistons 1 & 5 are fully raised, thus 1 is about to spark & 5 is evacuated.
engine will turn freely (no piston to valve contact) with the cams
180o out, it will even run (roughly) with 1 out 180o, any other
settings may cause major damage to the valves.
2 cam shafts come with timing markings, "yes" real timing marks that
anyone can use (even without special tools) to ensure correct timing.
The way to time it is to ensure both the off centre cam shaft slits are level/flat with the head.
the engine at TDC both the cams need to have the off centre slot in
the same position either up and level or down and level.
is super critical that both the camshafts are 100% in sink with each
other, i.e. not a few degrees off, the engine computer can compensate
for crank timing but not engineering failure.
warned the camshafts can turn easily fast & hard by themselves as a
few springs are compressed at TDC, I got my finger jammed and its
still healing + if the engine is not at TDC you may damage a valve.
heres the hard thing that you will need special tools for - if you
need to change the timing, you will need to be able to undo the cam
sprocket bolt on both cams & these are done up real tight.
is a tool that you attach that has 2 pencil thick shafts that fit into
the sprocket and prevent it from turning - then you need to put about
90Nm of force on the bolt (remember the rear one if LHT)
the $money$, its well worth getting yourself the tool kit - it will
save you hours in the long run. Search eBay for otc-6488 should be US
$119 - then sell them again for say $100.
is also a tool version of the oil tensioner in the kit that screws
right in and puts the correct amount of force on the chain + guide, to
enable you to do up the cam bolt with the chain and sprocket in the
right spot on the cam.
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