Valve Clearance Adjustment on FZR400

[Spizzak]

This is a basic valve clearance adjustment I did on my 1988 FZR400, the process is very similar for other inline 4s and pretty similar for v-twins as well. You may notice from the pictures that I didn’t follow the order I outline in this guide during my job but that is just because I didn’t know exactly what I needed to remove to get at the valves and I also decided to change the head gasket half way through this job. Therefore I have made some changes to reflect my mistakes and the easiest way to do it. Sorry if I missed pictures of anything it’s really hard taking pictures while working on the bike and my helper was only there some of the time.

So without further ado here is my guide for a VCA and head gasket replacement on the FZR400.


Tools you might not have but will need:

• Torque Wrench (essential part of any job)
• Thickness Gauge (should be able to measure 0.001 or at least 0.002 inches)
• Hex Sockets
• Micrometer (optional)

* The convention for numbering pistons and in turn valves is 1 to 4 from left to right when sitting on the bike.

[Spizzak]

1. Preliminary Work

The preliminary preparation depends on how much you intend to do. For just the VCA (expect around 10 hours) you’ll need to remove as much as you can from the valve cover area in order to have enough room to work with the camshafts and valves. This includes:

1. Upper, mid and tank fairings
2. Radiator
3. Airbox
4. Possibly the gas tank
5. Radiator filler with hoses and thermostat
6. Coils
7. Rubber/plastic Cover between valve cover and electronics (the thing the coils are mounted to)

If you’re going to be pulling the head (add on a few hours) you’re going to have to remove a few additional things such as:

1. Carburetors
2. Drain Oil and Coolant
3. Oil Delivery Line
4. Right Down tube

As you can see in the pictures my bike has a few extra items removed as well but this is just because I was doing other work on the bike at the same time and is not necessary.
It also helps to take some pictures along the way to help you remember some things you can easily forget such as cable routing and some item’s locations.
Once you have these things removed you should have a nice clean working area with enough room to move and work around the head, and you can move on to removing the valve cover.

PICTURES

[Spizzak]

2. Valve Cover Removal

Before you remove the valve cover you might want to blow out the recess where the spark plugs are located as a lot of dust and gravel seems to accumulate there that you don’t want to get in your engine.
Once that’s done, loosen the bolts on the valve cover in a criss-crossing fashion and remove the head by working it off slowly and evenly from all sides. Then move on to measuring the clearances.

PICTURES

[Spizzak]

3. Clearance Measurements

Now that you have the cover off, you should see the camshafts (covered by the camshaft caps) and the camchain (covered by the upper camchain guide).
Next you’ll need to remove the alternator cover and turn the alternator counter-clockwise via the big nut on it until you see the “T” on it line up with the line on the crankcase. Now you’ll need to check if the cam lobes on piston 1 are facing out (away from each other) if so good. If not rotate the alternator 360 degrees.

Now with the lobes for piston 1 at TDC (Top Dead Centre) you want to measure the 4 clearances for this piston’s valves (2 intake – top ones, and 2 exhaust – lower ones). Do this by trying the minimum clearance sized feeler gauge and working from there until you find the one that just barely won’t go in, you’re clearance is one less than that. (You may need to combine two blades of the feeler gauge to get the denomination you want if it doesn’t have it)

At this point you’ll want to make a neat and organized table for all your measurements. Here is an example:

http://www.fzrarchives.com/images/va...ance_notes.jpg

Once you have your clearances for the first piston rotate the alternator counter clockwise 180 degrees to measure #2, 360 for #4, and 540 for #3.

Acceptable Clearances (Cold engine)
Intake – (0.004~0.008 in)
Exhaust - (0.008~0.012 in)

Once you have all your numbers you’ll know how many valves are out of spec and thus need to be replaced. If they are all in spec you’re bolt her back up and you’re done, if not move on to replacing the shims.

PICTURES

[Spizzak]

4. Replacing the shims

In order to replace the shims you will need to remove the camshafts. The manual is pretty detailed here, just follow it. You’ll need to remove the two camchain guides ***Make sure you secure the chain to something on the engine block (I used fairing mounts) so it does not fall into the crankcase. Next you’ll have to remove the camchain tensioner (between the carb boots). Then, remove the camshaft caps, once again criss-crossing the bolts and remove the shafts evenly from both sides. Now you can lift the camchain of the shafts and pull the shafts out.

You should now see the valve lifters (16 quarter sized circles). Under each of these is a shim. Using a magnet pull the lifters off. ***Make sure you don’t drop anything in the crankcase
Once the lifters are removed you will either see the shim sitting in the middle or there will be hole where this shim is. If the shim is not there it is most likely stuck to the inside of the lifter.

Go ahead and pull all the lifters off that need to be replaced and place them on a sheet of paper along with their shims and mark them so you know where they were. Now inventory your old shims and refer to the chart to see which size shim they need to be replaced with. (If you don’t trust the writing on the shim or can’t read it, use the micrometer to measure its thickness).
Now that you know what you have and what you need, check if you can switch any of them around and then go pick some up for the rest. They are 7.48mm diameter shims so if you want to get generic ones, that’s the size you need.

Once you have them apply some moly grease, put them back, and cover them up with the lifters.

PICTURES

[Spizzak]

5. Replacing Head Gasket

*** This part only applies if you have decided to replace the head gasket as well

The most involved part of this procedure is the cleaning. Just remove the cylinder head nuts in the order the book tells you to (they use a 6mm hex socket). You may want to remove the oil from the nut cavities so it doesn’t pour into the coolant tracts.

Now slowly work the head off (be careful as there will be up to half a cup of coolant just waiting to spew out when you do this). Make sure you remove the head evenly and have someone feed the camchain through it. Discard the old head gasket and clean off the pistons and valves (make sure you don’t lose and lifters/shims while you clean the valves- it may be best to just take them off and just reinstalling them after). You should also try to get as much of the old coolant and the oil that probably leaked into it out of the cylinder (I used a little syringe with a small piece of fuel line for this). As you can see my pistons and valves were just disgusting.

Install the new head gasket after everything is clean enough and put the head back on, once again feeding the camchain through the head. Finish by torque-ing the head the same way you removed it.

PICTURES

[Spizzak]

6. Putting it all back together

At this point you should have everything you came here to do done, with putting the bike back together your only remaining task. This is where the pictures of where everything was help.

Check to see that the alternator shows TDC, you can also confirm that the crank is not off by 360 degrees by making sure the wire that’s holding the camchain is in the same location as before. If it is not, rotate the crank 360 so it is.

When putting the camshafts back in make sure you put the exhaust shaft on the exhaust side and vice-versa with the intake one.

Install the camshafts and put the chain back on them (you can remove the safety wire at this point). Line up the two markers (black dots) with the camshaft caps and tighten the caps down according to the manual.

Now if everything seems okay, push down on the camchain between the two sprockets just enough to make it taught (so it doesn’t skip on the gear), and rotate the alternator slowly to make sure that after 720 degrees everything is still lined up. Now install the camchain tensioner and rotate a few more time to make sure everything is perfect and you’re done! Reinstall the alternator cover and the valve cover, and put everything you took off back on. If you drained oil and coolant make sure you refill those (a coolant flush would probably be a good idea too). You can now start the bike and enjoy the benefits of having your valves adjusted properly... probably starting with a carb tune :P


Well that’s it for my guide, I hope it was helpful for at least a few of you. If anyone has any suggestions or corrections feel free to correct me. Good luck guys, rubber side down