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Just done my Valves and need advice

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Hi, using the information on the Forum I did my valves on my 525 EXC for the first time today. It was quite easy, the longest bit was getting the tank and rads off, then the most fiddly bit was actually getting the feeler guage in.

After doing it all, and hoping Id got it at the correct TDC (not 180 degrees out) I made the adjustments to both the Intake and Exhaust - is that correct ?

I put it all back together and ran it, went out for a quick 10 min spin and some front wheel lofting, then came home and let it run for a while till it got hot. It seems fine, made the right amount of loose noise and seemed to run OK.

Is this all I need to do to check it ? I assume it wouldnt run at all if Id got the TDC wrong ? Also I assume it would run really badly if Id got the adjustmets wrong.

Any comments would be appreciated and Id like to be able to do it myself and my first race is two weeks away !

Thanks.

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Did you have to make any big changes in the adjustment? If you where 180 out you would have to have loosened each a turn or more of adjustment.

Next time try it my way, no chance of being 180 out, no need to remove skid plate, magneto cover or spark plug.

Valve adjustment

KTM RFS (or ANY 4 cycle) engine

Top Dead Center: Commonly referred to, as TDC is the point where the piston is up.

Power stroke: On a 4 cycle the engine produces power every other time the piston is up, while the piston and crank are in the same position (TDC) every turn the cam turns ½ of crank speed so the cam is in its position to adjust, both cam lobes facing down every other turn! Thus you cannot just put the piston at TDC and adjust, the odds are 50/50 that the cam is in the right spot.

Overlap stroke: The other turn where the piston reaches TDC is called the overlap stoke, the valves are each open very slightly, approximately 1mm with the exhaust closing and the intake opening. Not the place to adjust the valves!

Clearance: To allow the valve to fully seat and transfer the heat it accumulated when open, and to allow for heat expansion when hot, the camshafts lifting pattern and valve train are designed to operate with “clearance” “lash” or “gap” between the valve train and the valve. Too much clearance and the cam and cam followers are prone to wear out. Too little clearance and it can burn a valve, or if you are luck, just not start at all so get it right. KTM has a service bulletin recommending that we ignore the prior specs and set the valves at .12mm which in inches translates pretty closely to .005”.

Rotation: Note that the engine rotates the same direction as the wheels and that when we rotate the engine we are fighting the valve springs, the easiest way is to put the transmission in top gear, this gives the wheel max leverage against the engine, conversely to how 1st gear gives the engine max leverage against the wheel. Then we rotate the engine by the rear tire. If you want to avoid pulling the spark plug out you can, just hold the manual compression release while turning the engine.

Getting to it: First remove the seat & tank, from there I have done it radiators on, and hated every minute of it, I have done radiators off, it is more labor but maybe less maddening? (On '03 try setting the radiators aside without disconnecting the hoses) Unless the bike is spotless I like to take a can of Brake Clean and someone else’s toothbrush, spray & scrub the valve covers and the area around it, then spray the area around the spark plug with the brake clean to flush out that area. If you have compressed air a good blast would help clean debris out of this area but watch you eyes! Then remove the valve covers and if you are going to the spark plug but if you do it my way there is no need on the plug.

Now we must locate the “heal of the cam” where the valve lash is to be adjusted.

Common way: The common way it to find TDC on the “Firing” stroke. The problem with this is too many folks end up on the “Overlap” stroke. This causes endless confusion, people putting straws down plug holes and endless other tricks that still often leave them on the wrong TDC.

My way: With this method you do not need to remove the spark plug, magneto cover, skid plate or the TDC bolt in the bottom of the crankcase or the associated dirt.

Intake valves; Transmission in top gear, rear wheel off the ground, if you have a helper one can watch the valves and hold the manual compression release while the other rotates the engine with the rear wheel. Rotate the engine gently with the wheel to locate the point where the exhaust valve starts to open then rotate very gently until the exhaust valves are 1/2 way open! Minor frustration, we are now fighting against the valve spring which wants to roll the engine back, so to stop it you either have to have a helper hold the rear brake or, as this gets pretty boring so;

Option 1; Take a tie down, hook one end to the brake pedal, wrap in under the bike and up the left side to something like the top of the frame behind the engine. Now just tighten the strap so the brake can keep the engine from rolling back.

Option 2; Put a bar thru the spoke of the rear wheel adjacent to the swing arm to stop the wheel.

At this point the Intakes are on Center of the Heal of the Cam. Proceed to adjust.

Exhaust valves; As above, except, locate the point where the intake valves have opened and are 1/2 way closed (engine rotating forward). As the intake is closing the engine will want roll forward PAST the ½ way point and the lash in the transmission and chain will make it so you can not stop the engine, so let it go just past, then roll the wheel backwards and secure it with the brake or bar again. Now proceed to adjust the Exhausts.

ALWAYS! ALL 4 STROKE ENGINES: With the engine rotating its correct direction the exhaust is adjusted when the intake is closing and the intake is adjusted when the exhaust is opening!

Adjustment:

If you are a “feeler gauge” kinda guy; As the clearance is so small and you can not get a straight approach with the feeler gauge don’t be surprised if you can not get it in. I like to loosen the jam nut (10mm box wrench) and loosen the (one at a time) adjuster a couple of turns, slip the gauge in, turn the adjuster down lightly against it, then tighten the jamb nut. In doing so often the adjuster will creep tighter slightly and cause the clearance to close up. What you need to do as you tighten the jamb nut is do kind of an isometric exercise where you are holding the adjuster against rotation with equal and opposite force of the rotation of the jamb nut! This may take several practice attempts. As soon as you have tightened the jamb nut, do not pull the feeler gauge out, just try to slide it around in the gap! When you have it right it should slide with some, but minimal drag or resistance, no drag and it is too loose, heavy drag and it is too tight, may even be holding the valve open? Take a little time, you will have to redo a few times at first but once you pull the gauge out you may not be able to get it back in so get it right first! Oh, and by the way, the jamb nuts need to be tight!

If you are a 1/6th turn kinda guy; I think it was the Husaberg guys that came up with the theory that fraction of a turn will do! The “Bergs have a different thread pitch, I think they use 1/5th of a turn? My first reaction was that is crude, then I tried it a few times, now do it every time. That is based on a turn equates to .75mm (on the KTM tread) and.75 div by 6 = .125mm and .12mm is spec so for all practical purposes 1/6 turn is right on! Loosen the jam nut (10mm box wrench) and very lightly tighten (one at a time) the adjuster till it contacts the valve, note where the screw slot is aimed, turn the jamb nut to a corner of the hex aliens with the slot, make a small scratch in the cover gasket surface in line with the next hex point left (hex being 1/6th turn to the next point). Then turn the slot to that point, then tighten the jamb nut. In doing so often the adjuster will creep tighter slightly and cause the adjuster to tighten up. What you need to do as you tighten the jamb nut is do kind of an isometric exercise where you are holding the adjuster against rotation with equal and opposite force of the rotation of the jamb nut! This may take several practice attempts. As soon as you have tightened the jamb nut just double check that it did not creep, the slot aimed at the mark we made 1/6 turn left of contact and move on the next valve.

The jamb nuts need to be tight and there are a couple of ways to deal with it;

1: Get out the torque wrench, check the factory spec and torque it down. Problem is with that is your locked into using a socket so you won’t have the screw driver resisting movement of the adjuster, if the torque was close it should be OK. If it turned the nut much it may creep the adjuster around and changed your clearance setting. Thus what you have to do is be very close by hand before putting the torque wrench on it.

2: Perfect way, fabricate a “crows foot” type box wrench so you can use the torque wrench and the screwdriver simultaneously. In doing so there is a leverage factor that needs to be computed to arrive at a different (lower) torque spec and you probably need four hands to do it.

3: My way again. Put a nut and bolt together in a vice and torque to the spec, put the undoubtedly shorter box wrench on it to get a feel for how tight that is. Repeat a few times and feel how tight that torque feels. Then set the torque wrench aside and do it by hand.

Now that we are done lets just double check our work, remove the bar from the rear wheel and rotate the engine forward to the checking points, hold it there with the rear brake momentarily and confirm a small amount of lash.

Re-assemble don’t forget, add coolant, return the toothbrush to its owner, go ride.

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Sounds like you got it right as long as you didn't move the adjusters more than 1/3 turn at most.

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I dug this up from the search feature.

I don't own a KTM but a friend does and he brought it over so we can adjust the valves. I used the 1/6 turn method and it was really easy. We also did the "rotate the wheel until the exhaust valves were half open and then vice a versa" deal for the adjustment. After getting it all together the engine had a distint ticking coming out of the head that sounded like the valves slapping closed. Not being a KTM owner I'm not sure if that is normal when adjust properly. My buddy just purchased the bike so he is unsure as well.

Thanks,

Brian

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I know this is an old thread, but I'm doing some research here before I check/adjust the valves on my '03 450exc. From the post above, the author is basically saying that you change the crank position between adjusting the intake and then the exhaust valves. However, I thought (from reading several other threads here) that both the intake and exhaust valves should be adjusted from the same crank position (i.e., there's no reason to rotate the rear wheel/crank once TDC is located and "locked down" (via the brake pedal in this case, or via the crankcase bolt in the "traditional" method).

Also, how do you know when the exhaust valves are exactly "half-way open." Would it help to use a zip-ty or straw in the spark plug hole just to confirm that you are at the exact correct position?

Can someone clear this stuff up for me?

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have you watched the video? I think it describes it and shows it very well, no need to lock anything, leave rads on, etc. 1/6th turn method.

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I know this is an old thread, but I'm doing some research here before I check/adjust the valves on my '03 450exc. From the post above, the author is basically saying that you change the crank position between adjusting the intake and then the exhaust valves. However, I thought (from reading several other threads here) that both the intake and exhaust valves should be adjusted from the same crank position (i.e., there's no reason to rotate the rear wheel/crank once TDC is located and "locked down" (via the brake pedal in this case, or via the crankcase bolt in the "traditional" method).

Also, how do you know when the exhaust valves are exactly "half-way open." Would it help to use a zip-ty or straw in the spark plug hole just to confirm that you are at the exact correct position?

Can someone clear this stuff up for me?

Yes I can clear it up, ONLY if you listen! YOU CAN NOT ADJUST AT TDC UNLESS YOU KNOW WHICH ONE YOUR AT!

TDC is crank possition!!!!!!!!!!!!!!!!!!!!!!!!!!!

We care about Cam position!

Cam turns 1/2 of crank speed! TDC is ONLY usefull when we are assembling the engine and it has not been rotated since the cam was installed. Once the engine has be rotated you must use cam position!

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Wow, calm down Dave. I'm not saying your way is wrong. I actually prefer it since it's the easy way :) I'm just trying to learn what exactly is going on with this technique. I'm listening, but I'm still confused. Let me ask you this: will using your technique result in the exact same valve lash measurement as with the "standard" technique? In other words, if I adjust the valves your way to .005", and then immediately start all over and use the "standard" technique, will the valve lash still be .005" when I measure it that way? Please be patient with me. I'm sure some other people are wondering the same thing.

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This is the "standard" technique that I'm referring to, posted by TT member Jeb:

Remove the valve covers. Now watch the cam lobes and valves on the intake/carb side of the head. Work the kickstarter until you see the lobes open and then close the intakes. There are two TDC's on a 4 stroke so make sure you're watching the intakes and not the exhaust side.

You probably won't be able to stop the cam rotation very precisely but that's okay. Stick a straw or ziptie (not the locking end) down the spark plug hole to show where the piston height is. Put the bike in 2nd gear and work the rear tire back and forth gently until the piston height indicator shows you the piston is at TDC. Then run the crank locking bolt in. Its shoulder should bottom out against the engine case.

NOTE: There are apparently several places on the crank lobe where the locking bolt will bottom out so make sure you have the right detent by making sure the piston is at TDC.

Check this KTM bulletin for valve clearence specs:

http://pws.chartermi.net/~jejb/pictu...e_bulletin.jpg

I use a motionpro tappet gauge to check the gap. I like the bent tip ones on this page. The price on the web page is for 6 of them:

http://www.motionpro.com/servicetools_3.html

Set the valves and make sure the adjuster nuts are tight. I use the .005 gauge. You should not have to turn the adjusters more than 1/3 of a turn at the most. If you do, you're either not at TDC or on the wrong TDC.

Then just button it all back up, reinstall the thick washer on the crank locking bolt, etc. When you put the anitfreeze back in, make sure you remove the head bleed bolt(s) first. It's an 8mm headed bolt with a crush washer located near the sparkplug hole on the 02. On the 03, there's another one on top of the right radiator. Pour antifreeze in until it runs out the lower hole. Reinstall the bolt and finish filling the radiators.

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Okay, I thought about this some more and I think I finally get the idea. Basically, when you check the valve lash, you want to make certain that the valve you are checking is in the completely closed position. You can be sure of this by:

A) first making sure you're not in the overlap phase, where both the intake and exhaust valves are slightly open. This is confirmed by checking that the exhaust and intake valves are not moving at the same time as you slowly rotate the crank via the rear wheel

:) on 'A' is confirmed, you make sure the other valves (i.e., the exhaust side when checking the intake side) are in a position approximately half way open (or closed), which guarentees the valve you are checking is completely closed

There is no need to know if you are at TDC with this technique, since all we really NEED to know is that the valve we are checking is fully closed.

Does all that sound right?

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Here is a writeup I did a while back that I still refer to whenever I check the valves. It compliments Travis's excellent video quite nicely I think:

I finally decided to try the valve adjustment on my 07 450exc. I decided to use the method that doesn't use the locking bolt at TDC and I am glad I did since it didn't involve draining the radiators. There are many good tutorials including a great video by travis, but some things still caused me confusion. Here is what I figured out:

1. Remove the tank, and left side tank support from the frame, then remove the screws holding the radiators on, but don't remove/drain the radiators.

2. You also don't need to remove the spark plug to relieve compression, just pull on the decompression lever at the engine (mine was not hooked up to a handlebar lever which is the way they come).

3. You need to put the bike in a high gear to make it easier to rotate the rear tire against the engine compression (easier said then done, but I put it in as high a gear as it would go).

4. I then removed the valve covers which was cake and the gaskets were still in great shape!

5. Now comes the hard part. Trying to rotate the rear tire forward while holding the decomp lever was a chore, so I tie wrapped it fully engaged (to the rear of the bike). (The decomp lever holds the exhaust valves slightly open to relieve compression and make it easier to rotate).

6. As you spin the rear tire forward, the valve lifters will move. If both the intakes (rear) and exhaust (forward) move at the same time, you are in overlap and need to keep spinning forward.

7. As the engine leaves top dead center, it will be hard to spin, then suddenly jump forward. After the jump, this is where you start watching the lifters.

8. When in the proper stroke for adjustment, the front exhaust lifters will move, but not the rear intake lifters. Spin the rear tire through a few stroke cycles and you will see the difference (front and rear lifters move together, vs just the front lifters moving, then the rear lifters moving).

9. Move the rear tire forward until the front exhaust lifters just start to move and release the tire. It will stay put or reverse just a little.

10. Now check the rear intake valves for adjustment (0.005 inch). The motion pro feeler gage works really good because it is stiff where you grab it, and the feeler gage thin steel is short at the head to keep from flexing.

11. My left intake valve was perfect at 0.005 in, but the right intake was at 0.006 in. This is within spec, but I adjusted it anyhow.

12. Just loosen the lock nut, turn the adjustment screw in slightly, and tighten the lock nut. Check again and you are good. (clockwise to decrease the measurement, or counterclockwise to increase the measurement). This should never be off very much. It only took about 1/4 inch of travel to change my measurement from an 0.006 to 0.005 in.

13. Now it is time for the exhaust valves and where I ran into problems. It seems you will never be able to put the feeler gage under the exhaust valves unless you remove the tiewraps from the decomp lever. Please don't make this stupid mistake like me.

14. So after you cut the tiewraps, spin the rear tire backwards (not forwards this time) until the rear intake lifters just start to move. (you adjust the intake and exhaust valves on the same stroke, just different positions).

15. Release the rear tire and check the exhaust valves. Since the radiators are just being held on by the hoses, they will easily move to one side to enable an easy adjustment. The left front is the hardest to get at, but you will figure it out.

Well that is it, I hope you have fun like I did. Watching Travis' video and my attempt at clarifying things should make this cake.

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Here is a writeup I did a while back that I still refer to whenever I check the valves. It compliments Travis's excellent video quite nicely I think:

Great Post :) That info confirms what I was thinking. Thanks!

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The first time I checked the valves on my 525, I was all nervous. Watched that video about 15 times. First time took about 2 hours. Every 20 hours I check the valves, and takes about 15-20 minutes now. I leave radiators in place, and leave the feeler feeler gauge in the tool box.

Best way to learn is to just jump in and adjust your valves.

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