KTM Valve Checking Procedure (All XC4 engines)

[Anonymous]

XC4 Valve Adjustment (XC4 is the designation for the single cam engine that as of this date has been introduced in the 08 450 & 530 EXC & XC-W-R

On this engine several procedures are going to be different than the RFS, checking is simpler, changing is slightly more complex but should not be intimidating. The good news is this is a more stable valve train so adjustments should not need to be quite a frequent? Time will tell. Anytime we have shims the factory gives a bit more “range” of acceptability rather than a precise number.

The factory specs (cold engine) are:

Intake = .07mm to .13mm (.0032” to .0052”) (Lets inch people call it 4 to 5 thousands)
Exhaust = .12mm to .18mm (.0048” to .0072”) (Lets call it 5 to 7 thousand)
Note, most of us here in the states have feeler gauges in and think in inches, if you can go either way it’s a good time to just start thinking metric as we are going to have to convert when we go buy shims anyway.

Note the shims available from KTM range from 1.72mm to 2.6mm, so I suspect the engines are designed to be in the middle, let’s guess 2.2mm will be common, but at a bit over $5 each my goal is to keep your inventory down to 4 to 6 spares.

Tools, In addition to common shop tools you are going to need:

1: Feeler gauges in several thicknesses above and below the spec. say .003 to .010”! While bent ones are preferred on the RFS I like the conventional gauges here as we need a full assortment.
2: A long thin ball point pen sized magnet.
3: A micrometer or dial/digital caliper would be nice! A slick way to do this inch to metric conversions is buy a digital caliper that reads inch and metric. You can measure what ever your working on, read it in inches, press the button and it switches to metric. So slick it should be illegal
4: A pencil & note pad.
5: Some paper towels so we can stuff the areas around the cam chain where a dropped shim can go “down”, object is to be smarter than the bike so lets just not do that.

Map; Now lets take that pencil and paper and make a map of the engine, an arrow pointed up the center of the page for forward or front of engine/bike, 4 circles for the valves top, left would be labeled LE for left exhaust, top right RE etc. Make the circles inch or more and not too close to each other so we have space to write! Make it neat, maybe add the “spec” clearances and a place to record date and hours on the bike, then run some copies if possible.

Some definitions:

“Intakes” reference the rear pair of valves
“Exhausts” reference the front pair.
“Left” references the bikes left, not yours.
“Item #” references the KTM parts schematic (available at “Parts On Line” at the top of KTMTalk.com web page), I will note which page of the parts catalogue such as See (Valve Drive) “Items” #22 means go to the Valve Drive page and look for item #22.
“Rocker Arms” references just that, the cam pushes up on one end, the other end pushes the valve down (open). You can see them at (Valve Drive) “Items #15 & #20”.

Checking the valve clearance:

Remove fuel tank, clean any debris around the valve cover.
Remove the 4 bolts that attach the valve cover and slide cover out to the left (it is tapered to make it easier to go left)
1: To check the valve clearance, rotate the engine to where both intake and exhaust cam lobes are down, equidistance from straight down, something like 5 & 7 O’clock. At this point there should be no tension on any of the four rocker arms! While this is TDC please, lets not go there, no need to remove the spark plug, break pencils off inside the engine etc. and remember every other TDC the lobes are up so we need to locate the cam and ignore the crank, please!
2: The point you need to measure the clearance is between the tip of the rocker arm and the shim which is in the center of the valve springs retainer/upper end of the valve.
4: Select your feeler gauge, start thin, say .003”, then .004” etc working up until we find what fits with some drag but not being forceful. Note with this design we need to find out what the clearance is where on the RFS we just adjusted to the spec!
5: For example the Left Intake (LI) was a .004” so we are going to start on our “Map” a record of LI (Left Intake) = .004”. Next repeat on RI and let’s say it was a .005” so we record that. I would right the clearance just under the circle on our map saving the center of the circle for our shim
So when complete we have a record something like

LI = .003”.
RI = .005”.
LE = .006”.
RE = .007”.

At this point I am going to lay out two copies of my “map”, one is sacrificial to lay oily parts on, and the other is clean for permanent records! I am going to make note of these valve clearance numbers right under each circle on my permanent map.

Adjustment:

Note the Rocker Arms pivot on a shaft that runs thru the head from side to side. They are secured by “Items” (Valve Drive) Plug #22 and fasteners #23 & #24. These retain this shaft.
1: Let’s remove those items and with one O-ring to keep track of the shaft should slide out to the right.
2: Now each “rocker arm” is loose, no need to remove them just lift them slightly, then reach in with that thin ball point pen sized magnet and pluck the shims out, this is in the center of the valve spring retainer, as they are oily again they go on the sacrificial map in the proper location.
3: Next lets check the shims as when it was manufactured it had a number etched in it, something like “2.2”. It may wear off in time but life is good if we can still read it. That would be the thickness in mm so 2.2 mm thick. Let’s take the clean/permanent copy of the map and make a permanent record by putting 2.2 in the center of the circle for that valve, etc., note the date, hours on the bike etc.
Assuming we do not have an assortment of shims available and assuming we are not far out of spec let’s put the bike back together and go order the shims, revisit the actual adjustment when they come in.

Ordering the Shims:

The KTM part number is 77036035220 for a 2.20mm, 77036035216 for a 2.16 (the next size thinner) etc, they go in .4mm increments which for all practical purposes is a thousand of an inch.

NB – these same shims fit all 08 engines, RC4, RF4 XC4 RC4 so dealers should be getting them in stock. The cost of $5.13 each is negligible when you’re organized as you will buy 3 to 6, significant when you don’t have a clue what you need. I would not expect a dealer to invest in an inventory so you can walk in and trade, my policy is I invest in the inventory, when a trade takes place I charge ½ of the price and put the used piece in stock.

Math example:

Up above we had a left intake (LI) had valve clearance of .003”, slightly tight for a spec of .0032” to .0052”. So we want to increase clearance, thus a thinner shim! So we pop that shim out and lets say it has a 2.20mm shim. The next size thinner is 2.16 which equals one thousand thinner so that should yield a clearance of .004”.

Making the adjustment; Lets keep it simple and pretend that 2 shims in the bike where 2.2mm and 2 are 2.16. I am going to go buy a few 2.16mm and 2.12mm shims, maybe a 2.24mm? Nothing that’s going to break the bank like it would if we placed an order not knowing what was in there. When a 2.16 gets replaced with a 2.12 it becomes a spare for when a 2.2 tightens up so a $30 inventory on your part will make life easy.

When the shims are changed, recheck via the same procedure and re-assemble the rocker shafts etc. Why we keep a record?

Rule of thumb:

Steel valves: When the shim required has changed by say .4mm the valves life is over. So if your original shim was a 2.20mm the range of down to 1.80 your valves are about done (and the thinnest shim is 1.72 so you’re going to run out of shim anyway.
Ti valves, are different, good news is they are much more stable, bad news is there tolerance for changes in dimension is much smaller so when the shim required has changed by .004” (4 sizes) its time, the valve is failing, lets change it now while the cost is hundreds as if you put it off its thousands.

[Mick DMember]

Hey Moto, For someone like me with a 530 sitting in the shed this post is gold. Thanks for posting it.

[Anonymous]

Thought you might like it Mick, I was pleased when I found it. I plan to check the valves pretty soon too.

[Author]

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