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In this video we'll show you how to adjust the valves on your 4-stroke motorcycle ATV.
We'll need a few different tools to complete this job.
First we'll need a feeler gauge so we can measure the clearances.
And Rocky Mountain has a few different options for you.
Next we'll need a few standard tools, so we can get to the valves.
But most importantly we're going to need our service manual.
This contains the very important, very specific specifications you need for this job.
It's also very helpful to have a caliper to measure the thickness of each valve shim.
We're also going to need some valve shims.
Rocky Mountain has these available in shim kits with numerous different sizes, or you
can buy them individually if you know what sizes you're going to need.
But we'll get to that a little later.
It's a good idea to start with your piston at top dead center.
Refer to your service manual for this, but most of the time there will be a mark on the
flywheel that needs to be lined up with the mark in the top hole.
You'll see our piston is currently at top dead center.
So first things first: we're going to want to start with a clean bike.
It's always easier to work on a clean motor, and also keep in mind that each machine is different.
This process will vary from machine to machine.
Today we're working on a 2007 Yamaha WR250F.
The first thing we're going to remove the seat and the tank.
After that is the spark plug cap, and the valve cover breather hose.
After that we're going to remove the two bolts from the valve cover.
Usually there are just two of these bolts, but sometimes you'll find three.
And once those are removed we can just remove the valve cover.
And that will reveal the valve train.
Now we can start measuring our valve clearances.
We're going to need our feeler gauges now and, to measure the valve clearance is simple.
All we're going to do is take the appropriate feeler gauge and slide it in between the camshaft
lobe and the valve bucket, which is also known as the tappet.
You want the gauge to feel almost sticky underneath the cam lobe.
If the clearance is bigger than the gauge it will slide in and out easily.
If the clearance is smaller than the gauge you'll know because the gauge won't slide in at all.
For illustrating purposes we've removed our cylinder head from the bike
to better show the adjustment process.
So removing the head is not required, and the steps that are shown will be the same
as they would with the head still on the motor.
We need to refer to our service manual and figure out what our valve clearance service
limits are and that would tell us what size feeler gauge we need to be using.
As you can see the service limits for this WR are .1 to .15 mm for the intake, and .17
to .22 mm for the exhaust.
Most all motors will have service limits similar to this motor.
So we're going to start with the exhaust side.
We're using our .20 mm feeler gauge, and as you can see it's sliding in under both of
the lobes, but not very easily.
So we're going to grab out .18 mm gauge, which is a little smaller and try that one.
You can see that it's a little sticky and that's exactly what we want.
So we're going to record that measurement because we'll need it later on.
With the right side measuring .18mm and the gauge went a little easier on the left side,
so we're going to record that as .19 mm.
Now we can start measuring the intake side, and we're going to start with our .15 mm gauge,
because it's the top for our service limit for our intake valves.
As you can see it slid into the right side just fine. Moving to the middle valve you
can see that it won't slide in at all, and the same case for the left intake valve.
So we're going to move to our .13 mm gauge and it looks like it's fitting perfectly in the right side.
The left intake valve and the middle are still not fitting, so we're going to record the
measurement for the right intake valve now at .13 mm.
Now we're going to go to a little smaller gauge to see if we can't find the clearance
for the left valve. We're using a .06 mm gauge and that slides in just fine; but the .07
mm gauge fits perfectly.
So we can record that clearance for the left valve now at .07 mm.
After that we're going to take our two smaller gauges and see if there's any clearance in the middle valve.
As you can see nothing is fitting between the lobe and the bucket, so we can record
the middle valve as having zero clearance.
So now that we've got our clearances measured and recorded we can begin removing the camshaft
so we can get to the valve shields.
The first step would be to remove your cam chain tensioner.
Keep in mind that yours will most likely be a little different than the one shown in this
video, so refer to your service manual for proper procedures.
The next step is to tie a wire around the cam chain so it doesn't drop down into the
motor when the cam shafts are removed.
We can tie that up around the handle bars.
And now we're loosening the cam shaft cap bolts.
Remember to loosen these in a criss-cross pattern to prevent causing any damage.
After the bolts have been removed we can pop the cam shaft caps off.
Remember there are usually a couple of aligning pins in each cap and an aligning clip that
need to be removed to prevent them from falling down into the motor.
After we've removed the caps we can go ahead and remove both the intake and exhaust camshaft.
Doing this will reveal the valve buckets.
The next step is to remove the valve buckets and shims.
A magnet works best for this, and ensures that you don't drop anything down into the motor.
Remove each bucket and shim and organize them on your table so they won't get mixed up.
Sometimes the shim will stay kind of stuck up inside the valve bucket, and other times
it will stay sitting down in the spring retainer, so pay attention so you don't lose it.
So we have got both exhaust buckets and shims removed and placed on the table.
We're going to do the same thing for the intake side.
Just grab the bucket with the magnet and make sure you have got your shim as well and then
place them on the table.
You want to make sure you're keeping everything organized between your motor and the table
during this whole process.
This is a very critical part to a valve adjustment.
Now we're going to clean everything up with a rag really quick to make it easier to work with.
It's time to refer to the specs from our service manual, and once again you'll see that the
intake is .1 to .15 mm, and the exhaust limit is .17 to .22 mm.
We need to check the clearances we've recorded and see which ones are still in spec and which
ones need to be adjusted.
As you can see both our exhaust valves are still in spec at .19 mm and .18 mm which is
right in the middle of our bracket.
And the right intake valve is still in spec as well at .13 mm.
So now we need to look at our other two intake valves and figure out the correct size shim
to install to get our desired clearance.
To figure that out we need to know what size shim were in the head.
This is where our caliper comes in handy.
All valve shims have their size printed on them, but sometimes that number can get worn off,
so if you're unsure of what size the shim is simply measure it with the caliper.
As you can see our left intake valve shim is measuring 1.7mm, and our middle intake
valve shim is measuring 1.63 mm.
So we're going to write that down.
With our left valve we need to go down on the size of the shim to get more clearance,
because right now it's at a .07 mm and it needs to be between .1 and .15 mm.
So if we get a 1.65 shim, which is 1.65mm thick, the difference between that and the
1.70 mm that was in it is .05 mm.
If we add that clearance to our current .07mm of clearance we should get .12 mm, which is
in spec so we'll swap that 1.70 shim out for the new 1.65 shim.
And since our middle valve has zero clearance, we're going to use the biggest service limit
for the intake, which is .15 mm, and subtract that from the shim size that was in it.
So 1.63 minus .15 mm equals 1.48 mm, and since they don't make a shim that size we're going
to use a 1.50 shim.
So we can go ahead and swap that shim out.
Okay, so now we've done the math to get our new shim sizes on the two intake valves that
needed adjustment, and we need to put our cams back in to check those clearances again.
Now we're reinstalling each shim and bucket back into their correct location.
When installing the shim be sure it seats down all the way to the end of the valve,
and then slide the bucket down over the shim.
Repeat this process for all the valves.
After that we're ready for the cam shafts and cam shaft caps.
Don't forget the locating clip and make sure your dowel pins are in place as well.
Do this for both cams, if applicable, and make sure everything seats correctly.
We can reinstall the cap bolts and tighten those down.
It's a good idea to refer to your service manual for this to avoid causing damage.
You'll want to tighten these bolts in a criss-cross pattern.
After you get those tight make sure the camshaft rotates smoothly.
If they do we can rotate the lobes back up to where they sit at top dead center.
This will allow us to get an accurate clearance reading.
We're using our .13 mm feeler gauge and it seems to fit about perfect with our left intake valve.
But it still won't fit under the middle intake valve.
But if we drop down to a .07 mm gauge it fits.
So at least it's measurable now.
So now the new measurement for the left intake valve is .11 mm, which is in spec.
And the new measurement for the middle intake valve is .07 mm which is still not in spec.
So if we swap that shim for a 1.45 shim the difference of those two is .05 mm, and if
we add the current .07 mm clearance to that it equals .12 mm of clearance,
which is right in spec.
We need to remove our cam shaft cap again, and remove our intake camshaft one more time
to swap the middle valve shim out for a new 1.45 mm shim.
So after we've removed the 1.50 mm shim from that we're going to set that 1.45 mm shim
down into place and replace the bucket on top of it.
After that we can reinstall the cam shaft and cam shaft cap, and once again tighten those bolts down.
Then we'll measure it again and it should measure something like .12 mm which it does.
So now all of our valve clearances are within spec, so we can start putting the motor back together.
The first step to that is timing the motor.
So we need to remove the engine plugs from the left crankcase cover.
The bottom plug is so you can get a socket in there and turn the motor over if needed.
The top hole has the aligning mark and shows the mark on the flywheel and as you can see
both marks are lined up telling us the piston is at top dead center.
If you don't see the mark on the flywheel you need to turn the motor over until both marks line up.
You're going to want to pop your cam shafts out one more time and apply a little assembly
lube to the lobes and journals of each camshaft.
We need to refer to our service manual for proper timing instructions.
As you can see each cam sprocket has timing marks on them.
So we're going to need to refer to our service manual to get the cam shafts in the correct position.
It's important to start with the exhaust cam and pull the cam chain tight up off the crankshaft
so there isn't any slack.
Align the timing mark where it needs to be and then run the cam chain over the intake
cam and align those marks accordingly.
It's basically starting at the front of the motor and then working your way back.
The slack in the cam chain will be taken up by the tensioner.
So we have our camshafts installed and timed using the mark on the flywheel and the marks
on the cam shaft sprockets.
Go ahead and double check your work according to the service manual.
Make sure everything is how it should be.
Remember the cam chain tensioner will not be installed until a little later.
  So now we're going to install our camshaft caps.
First we set the locating clip down onto the bearing.
Be careful not to drop it.
And then make sure we have our two dowel pins still in the cap and set that down onto the camshaft.
It should just pop into place.
And then we're going to do the same thing for the exhaust side.
Sit that locating clip down into the groove on the bearing, and then set the camshaft cap down into place.
Then we can put the cam shaft cap bolts into place and begin tightening those down.
Again, we need to tighten these and torque these bolts in a criss-cross pattern to avoid causing any damage.
Refer to your service manual for proper torque specs.
So after those have been properly torqued we can go ahead and put those two engine plugs
back into place and tighten those down.
Now that those are tight we can install the cam chain tensioner.
Remember that your tensioner may require a little different install than this one did,
so be sure to refer to your service manual for this.
The next thing we're going to do is apply a light coat of silicone to the cylinder head surface.
That's going to help the valve cover seal a little better.
And then we can just set that valve cover up into place.
You'll notice we've already got the gasket on the top part of it.
Then we can reinstall the two bolts on top and tighten those down.
The next thing we're going to do is reinstall our spark plug cap.
Now we're going to slide that cylinder head breather hose down into place and route that accordingly.
After that we're going to reinstall the tank, tighten those bolts down.
And once the seat's installed we're done with this valve adjustment.
If you have any questions call in or visit our website. Rocky Mountain ATV/MC is the
leader for parts, accessories, and apparel for your UTV, ATV and motorcycle.
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How To Adjust Valves On A Motorcycle Or ATV - Shim Type

162 Folder Collection
Syuan published on September 7, 2018
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