Name: 如何調整摩托車或ATV上的氣門------------------------------墊片類型 (How To Adjust Valves On A Motorcycle Or ATV - Shim Type)
Uploaded: 2021-01-14T07:52:55.000Z
Duration: 13 min 55 s
Description: 【看影片學英語】數萬部 YouTube 影片，搭配英漢字典即點即查，輕鬆掌握單字發音與用法，長久累積看電影不必再看字幕。

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.

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.

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

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

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

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,

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

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

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

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

You want to make sure you're keeping everything organized between your motor and the table

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

As you can see both our exhaust valves are still in spec at .19 mm and .18 mm which is

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