How to lap valves on Honda motors

           Benefits of lapping valves

 The biggest benefit to dealing with dis-assembly, lapping and reassembly one valve at a time is that you cannot accidentally install a valve in the wrong combustion chamber. In other words, each valve is lapped and installed in the same exact section of the head where it was originally installed. This is extremely important because no machining is being done to the heads to true things back up. Basically moving parts get where patterns over time and each valve and valve guide will where together as a matched set. Installing a valve from one chamber in to another chamber will result in unmatched where patterns and typically shorten the over all life of valve train and this is why it is so important to reinstall the valve in its original location.

                  Tools

• New valve stem seals
• Valve lapping compound (course/fine)
• Valve spring compressor
• Magnet
• Suction cup
• Napkins

Step 1
With  the Head off the car you first need to remove the valves. Do this only one at a time as its best for the valve to go back in its original location. Take your valve spring compressor and place it as far at the bottom of the spring as possible and compress the spring. Then you need to take a magnet and remove the keepers. There's 2 on each valve you do.
 
Step 2

 Once the keepers are out put them somewhere you wont loose them! now you can lift the valve spring up and uncompress the spring. On the top of the spring is the retainer.

Now all you should see left is the valve stem seal. you need to get a gripping pliers and pull out the seal. You have to pull somewhat hard to get them out. once its out throw the old one away. If you see oil once the seal is off clean it up.

Step 3

You're now ready to get the valve lapping compound. You need to start with the coarse grit first. Put a little on your finger and go all the way around the valve as shown in the pic.

   Step 4 

Take the valve with the lapping compound on it and put it back in the head. Now take a small suction cup and put it on the valve and turn it side to side. this is lapping the valve. You will hear a grinding noise at first which means its working! Keep doing this until the noise quiets down. Then take out the valve and clean the lapping compound off it and also in the head. Then take your fine lapping compound and do the same thing with it until its quiet. Clean off the valve and inside the heads again.

Step 5

 When your all done lapping and everything's clean put the valve back in and set the head down flat. The valve stem seals you got should have came with a small piece of straw. Put this on the top of the valve stem as shown

Step 6

 Take the valve stem seal and push it down until it looks Flush on the cylinder head valve port. The seal wont go down all the way. This is normal. When you put your springs back on it will push the seal down automatically so dont even worry about it.

With the seal pushed down take the straw out. then take your valve spring and place the retainer on the top of it.

Step 7

  Now compress the spring and place it on the valve stem seal. Get the 2 keepers and put them back in. You may want to get some white grease to put on the inside of the keepers to help them stick on. If your having trouble getting the keepers in place try compressing the spring more.

Once everything's in place take the spring compressor and lift it up until the retainer moves up to where the keepers are. Then uncompress the spring as shown.

Step 8

  Your all done with this valve!!!! Repeat the same steps for the rest of the valves. Try to spend more time on the exhaust valves when your lapping because they need it more than the intake valves usually do.

After Lapping 

 1. With the guides straight, round, and snug,,,, in other words in good condition, not lose and worn out.

2. After you have accurately dressed your stone and ground the valves.

3. After you have done a careful valve job.

4. With the head upside down and the seats facing up, barely insert the valve in the guide. 

5. With the valve held about 1.5 inches above the seat, drop the valve and it should bounce 2 or 3 times and ring like a church bell. That seat is concentric to the guide centerline.

6. If you drop the valve and it goes "thunk" and stays on the seat, then one side or the other is wedging against the seat. If your lightly raise the valve off the seat with your fingertip, from the stem end, you can feel some light resistance, that's further proof that you need to recut the seats.