valve adjustment

will embark on my first valve adjustment on 02 520. found a good review off prceedure on holeshot, but, still have questions. excuse any for sounding "dumb."

1. finding tdc. on my xr this was simple as there was a window where one could turn the crank with a bolt and look for lines in flwheel. i do not see a window on the ktm, do you remove the side cover? whats the deal here?

2. the bolt that is tightened at tdc. how does this work. you loosen it prior to looking for tdc, find tdc, then tighten it back up? then when the valves are adjusted loosen it again, go past tdc then retighten?

3. what are you gus running as far as intake and exhaust clearances?


I just did mine last week, so the topic is fresh.

1. TDC - place a soda straw in spark plug hole, but first blow out the spark plug recess by blowing compressed air into the hole on the side of the head right below the spark plug, then remove the spark plug. Put the bike in 6th gear, so you can use the rear wheel to rotate the crank. It would probably be beneficial to remove the side cover, but keep in mind the piston is at the top of the cylinder twice, not just at TDC. When the straw is at it's peak the piston is at the top of the stroke.

2. The crank bolt you are referring to is on the right side of the engine. Loosen it and remove the copper washer, the put in back in. This will allow it to be screwed all the way into the crank at TDC. Then once the valves are adjusted, take it back out, put the copper washer back on, and insert and tighten. The washer is what keeps it away from the crank.

3. Exhaust .006" Intake .004"

Be patient finding TDC. Remember the final stroke is exhaust, so if the exhaust valves are loose just prior to the piston being at the top you need to spin the crank one more revolution to the top. Good LucK!!

[ November 02, 2001: Message edited by: Strick ]

On the crank case bolt, does it screw into a threaded detent in the crank or flywheel, or does it simply tighten up against the crank or flywheel? ie. does it help ensure tdc by having a threded hole for the bolt? My guess is the latter. Am i correct in thinking the intake and exhauset rockers are "loose" at tdc as the valves are closed.


The crank locking bolt has a tapered tip which fits into a grove in the crank at TDC. You can use a flashlight and look into the hole and see the locating grove. Remember that the crank turns over twice for every one revolution of the cam. You must be at TDC on the compression stroke. I find it much easier to time the valve adjustment with a oil change. Dump all the oil out of the motor and then remove the shift lever and then the mag cover on the left side of the engine and use the flywheel nut to turn over the engine with the spark plug removed.

Use a soda straw (don't use anything hard like a scrw driver, etc.) in the spark plug hole to help you find TDC. When you adjust the valves you must be on the compression stroke both intake and exhaust valves closed.


Originally posted by Jason C. Brown:

.... Am i correct in thinking the intake and exhauset rockers are "loose" at tdc as the valves are closed.


That´s how i do it on my bike, and i also use the straw. But it is not a KTM, it´s a Husky. If you are on the End of the Compression Stroke, the Rockers got to be loose and thats the right position to check and adjust the valves. If one rocker, it is normaly the intakeside, is not loose than you are at the cut end of the exhaust stroke. ´Cause in that moment the intakevalve opens already to use the outstream of the exhauststroke to suck in fresh mix. I hope i am right so far it is not that easy to translate in english.

[ November 06, 2001: Message edited by: Ferrari ]

TDC occures immediatly after the intakes close, it is better to turn the engine over with the flywheel, cause it happens so quickly. Be sure and find the indent in the crank locking bolt hole because right after that the auto-decompress starts putting pressure on the exhaust valves.

I adjusted the valves on my '01 520EXC last week - and I ended up doing it twice because I didn't find TDC properly the first time around. It's worth the effort to remove the ignition cover and use the bolt inside to turn the engine. (I didn't have to remove the shifter lever to take my cover off.) That's what I did the second time around. I was able to control the rotation much better. The first time, it over-rotated past TDC and I ended up adjusting the auto-decompression right out of the engine. The starter wouldn't even turn the motor over and the engine rattled like crazy when I finally got it going.

To find TDC, put a straw down the spark plug hole then rotate the engine counter-clockwise - I think. Watch what direction the motor turns when you hit the kickstarter - and that's the direction you need to go. Anyhow, rotate the engine until you see the intake valves compress and keep going - slowly - until you see them close. Watch the straw and when it's at its highest point - that's TDC. The locking nut should screw into the slot on the crank easily in that position and the crank should then be locked at TDC.

Good luck. It's not a bad project to do at home.


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