LC4 Valve Inspection
Contents
1. but don t believe they will be too much of an issue Some of the information provided is basic 4 stroke theory amp design and may apply to brands and models other than KTM Tools amp Parts 1 A Motion Pro valve lash feeler gauge 006 or 0 15mm or reasonable facsimile 2 A set of metric Allen wrenches You may find it necessary to cut down the short end of a few of your Allen wrenches to improve access to some fasteners As an alternative to cutting down Allan wrenches if you have a small 1 4 ratcheting wrench and short metric Allen insert bits much like cut down Allens they can really come in handy on some of the limited clearance rocker cover bolts 3 A set of metric Allen sockets preferably 14 drive 4 A set of metric sockets again preferably 1 4 drive 5 A 1 drive ratchet and extension assortment 6 Miscellaneous hand tools such as screwdrivers pliers band aids and so forth 7 m not going to list a torque wrench because most folks don t own a torque wrench let alone the more preferable but not so easy to find 1 4 torque wrench 8 New rocker cover gaskets yes you can reuse the old ones once if they are in real good condition 9 Now would be a good time to consider replacing the spark plug if it has 5K miles or better on it 10 Some Zip ties in assorted sizes Why a 1 drive set rather than the more common drive The third rule of professional mech2. one valve can affect the other besides if you re reading this you could probably use the practice When you loosen the jam nuts unless you have the previously mentioned 14 drive torque wrench you will want to note the effort required to do this as you will attempt to replicate the original torque value by feel If you do have a torque wrench find an easily accessible fastener of the same size on your bike and torque it to 12 ft lbs now lay a wrench on it and get a feel for that value When you re torque the jam nuts try to duplicate that value by hand Something you will notice is that when you re tighten the jam nut the lash actually loosens slightly this is from the nut pulling the adjuster stud hard up against its threads You will undoubtedly tighten and loosen the jam nut several times checking the feel each time This is fine do it myself every time have to make an adjustment When it feels right and the jam nuts are torqued and it still feels right Congratulations You re almost done You can still do this job with a regular feeler gauge blade if you so choose but it is very difficult if not impossible to check the clearances have done it both ways and prefer the check method to the mandatory method About all you can do is back off the adjusters place the conventional blade into the excessive gap and run the adjusters down onto the blade check the feel a
3. the piston is being used only as a point of reference relative to the valve train When you reach the point where the rocker covers are off and the plug is out it takes about 30 seconds to do the rest honest gt Part Three Inspecting adjusting valve lash What you are checking is the clearance lash between the rocker arm threaded adjuster pad and valve stem tip It should be 006 cold Too much and you have noise the potential for damage and a reduction in cam timing duration with the subsequent loss of power To little and you have the potential for damage This is where the right feeler gauge comes into play To do this job as quickly and easily as possible you should have the right feeler gauge the Motion Pro design is the best and only way to go unless you are a cheap bastard like me and want to make a copy of the Motion Pro The Motion Pro gauge has a stiff metal handle about 3 inches long and a short about 1 2 narrow blade riveted to each end bent at about a 90 angle You will want to readjust the blade to a less severe angle How do you make a valve lash feeler gauge Easy Simply take a 006 feeler gauge blade and epoxy it between two thicker blades to make the handle with approximately 1 2 of the 006 blade extending past it Put about a 45 angle on the blade and your ready to go The idea is that with the space you have to work in being very limited the stiff handle offe
4. How to inspect the valves on a KTM LC4 In three easy steps How to inspect the valves on a KTM LC4 In three easy steps Having recently been asked by both absolute beginners as well as skilled individuals the process for inspecting adjusting the valves on the LC4 engine decided to write this guide As an ex motorcycle technical writer and instructor take great satisfaction in someone performing a complicated task successfully and for the first time with nothing more than my written instructions and maybe the occasional poke in the ribs have written the steps to this process individually several times but have never put it all together in one bite until now This has been written for someone that has fair to good mechanical aptitude If you re reading this with intent and you ve never spun a wrench you are a brave soul If you can take your bike apart and put it back together and it still runs you may find this mildly entertaining but by no means new information Part One Getting there We will use the 640 Adventure as our example as it is the most complicated to field strip model of LC4 and the one happen to own It is also the model that most of the folks reading this will own as well If you own an SXC SMC or LC4E the vast majority of this information still applies you simply have fewer parts to remove and reinstall Lucky you No doubt there are some variations from year to year
5. anics is use the smallest tool that will reasonably do the job Most fasteners on the LC4 engine are small and have relatively low torque values there are no fasteners on this job that require using the larger bulkier and with greater potential for excessive leverage drive set E ree Proper Atmosphere That s right atmosphere Ji What mean is a well lit and relatively clean environment where you will not be distracted or disturbed A separate clean space away from where you will be working to safely store the parts that you have removed Nothing more entertaining than turning around suddenly startled from your dog chasing your cat thru your tools and kicking your gas tank across the room or if the tank was full breaking your big toe so badly you need morphine Drifty has suggested some laid back tunes like old blues or if your like me maybe some Emmylou Harris The idea being that you will have less a tendancy to throw things or try to put a pipe wrench into your cylinder head Disassembly will not waste your time outlining the details of things like tank or fairing removal if you can t do these tasks you may want to take your bike to a Dealership or a trusted and mechanically inclined friend with a copy of this guide Is your motorcycle clean If not after removing item four you may want to give the engine compartment a little bath Don t want big chunks of dried mud or little ro
6. cable attached to the front cover or remove it your choice 3 You may need to snip a zip tie or two along the way to move a harness or cable out of the way 4 See items 6 and 7 above 5 At this point you should have more than adequate access to the four rockers and their adjusters If not one of us has forgotten something and it might not be you because Yes am doing this from memory That s it on to part two Part two Finding TDCC A great deal has been written in this and other forums about finding TDCC Some descriptions are quick and easy written by and intended for people who have a good grasp of how a 4 stroke engine works Other descriptions written by some well meaning folks who undoubtedly think that the factory service manual was handed down to Moses along with the Ten Commandments F are simply parroting that material lts not necessarily wrong it s just painfully slow and amateurish First don t worry about finding exact TDC Compression top dead center compression Both intake and exhaust valves must be closed for several degrees before and after TDCC otherwise there would be no compressed mixture to ignite and consequently no power stroke A four stroke engine s intake valves open a few degrees before TDC Intake at the end of the exhaust stroke and close several degrees after the BDC Intake which is the beginning the compression stroke The Easy Way When yo
7. cks falling in your motor do you Is your motorcycle engine at room temperature Don t perform this task 45 minutes after riding into the garage It takes several hours for an entire motorcycle engine to cool to room temperature You will need to remove the following parts from the motorcycle 1 Seat One bolt 2 Outer fairing Six bolts two turn signal electrical connectors 3 Fuel tank You do not have to remove your inner dash but it helps to get it out of the way for tank removal Use tie straps or elastic cord to tie the ears of the dash up to the handlebars One nut three fuel hoses one vent hose if any 4 Cooling fan Don t force it it comes out easy once the back tabs are popped from behind the radiator Two screws one electrical connector 5 Front rocker cover to frame vent hose Two screw clamps 6 Rocker covers Save the covers as the next to last parts you remove or disconnect Three screws each watch the washers 7 Spark plug Save this as the last part you remove or disconnect If you have a compressor blow out the plug recess thoroughly prior to pulling the plug 8 It is not necessary to remove the radiators It does make access a bit easier but it is a trade off in time and hassle You will need to partially remove and hold away the following parts from the motorcycle 1 Coil one bolt 2 De compressor cable back off adjustment and disconnect from lever you can leave the
8. nd tighten your jam nuts amp Almost home Once the valve seats and valves have broken in a few thousand miles the adjustment doesn t change much it s much quicker to check the clearance with the Motion Pro gauge or homemade version than a mandatory re adjustment of the clearance every time Give yourself lots of time to do this task if it s your first time Double triple check everything as you go be methodical and orderly you ll be fine Once you ve done it a few times you will find the entire process can be performed in a about an hour give or take seldom rush What is the carpenter s first rule Measure twice cut once When putting everything back together simply reverse the steps Don t over torque any fasteners and don t forget to install new zip ties where needed A bit of light grease on the four round tank rubber mounts help the tank to slide into place a bit easier When you light it off after finishing and everything sounds as it should have a cold one give the dog and cat a treat for not getting in your way and give yourself a pat on the back for a job well done Chris Creeper Hickson For their assistance in editing this guide and offering their input l d like to thank Drif10 Meat Popsicle ChrisC Loadedagain Dagwood Godspeed RECI Passmore
9. rs more control and eliminates blade flex and bending problems associated with a conventional feeler gauge blade Doing it What Meat refers to as The Moment of Truth S When you first insert the blade into the clearance between pad and stem tip it may take an unusually high bit of effort to do ignore this and pay attention to the feel of the blade after insertion a bit of drag or resistance on the gauge is what we are looking for Slide the blade back and forth a bit to get a feel for the resistance It should be like how to describe feel Do you have a roll of scotch tape Slowly pull some tape off the roll feel the resistance Kinda like that If you find that it requires a bit more effort than described in the tape roll analogy to move the blade back and forth you have a tight six closer to a 005 clearance If you can slide it back and forth easily with only slight resistance you have a loose six closer to a 007 When I have either of the above described feels call it good and record my clearances for future reference and to track any valve clearance trends lf your feel goes beyond the described limits then it s time to readjust the lash to within specification If you need to make an adjustment even if it s only on one valve you will want to loosen both jam nuts I ve found that due to the rocker arm s clearance on its shaft the adjustment and feel on
10. u have taken off enough parts to see the rocker arms and valves do as follows Elevate the rear wheel make sure you have removed the spark plug and then shift the bike into 5th gear Rotate the rear wheel in the forward direction a few revolutions and watch the rocker arms open and close the valves see how that works Disregard the auto de compressor clack it won t hurt you Turn the rear wheel very slowly right after the intake valves open then close stop OK good so far You are now somewhere after BDC C bottom dead center compression and approaching TDCC Put a soda straw in the spark plug hole until it rests on the piston slowly turn the rear wheel and watch the soda straw rise up the plug hole At this point if you want you can use a focusing flashlight to actually see the piston rising in the cylinder on it s way to TDC If you overdo it and go past TDCC and the piston starts to go back down simply turn the rear wheel backwards a bit Weather you check the valves a bit before or a bit after TDCC is no big deal as the valves are closed for several degrees both before and after TDCC Once you are near TDC about to 1 2 from either side of TDC is just fine you can go ahead and check your valve lash hope this all makes sense to you it is actually allot quicker to do than it is to describe Its nothing more that rotating the engine to a position where all the valves are closed the position of
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