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In-Depth Engine and Fuel 
System Maintenance and 
Repair Manual  

2012 KTM 250 SX-F 

 

Summary of Contents for 2012 250 SX-F

Page 1: ...In Depth Engine and Fuel System Maintenance and Repair Manual 2012 KTM 250 SX F ...

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Page 3: ...Jeremy Jonas December 2 2013 Denton TX ...

Page 4: ...hanging the Fuel Injector 7 Replacing the ECU 8 Testing the Fuel Pump 10 Common Maintenance and Repairs Engine 11 Checking Valve Clearance 11 Changing the Piston 13 Checking the Cylinder for Wear and Damage 18 Checking the Crank Rod Bearings for Wear 20 Checking the Main Crank Bearings for Wear 21 Checking the Timing 22 Engine Tightening Torques 23 Bibliography 26 Index 27 ...

Page 5: ...This manual covers two main sections Fuel and Engine When a problem arises with your motorcycle refer to the troubleshooting section and then look to the suggested instructions for the diagnosed issue For maintenance you should follow the original maintenance procedures from the KTM Owners Manual The instructions for the common Engine and Fuel maintenance that are not included in the Owners Manual...

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Page 9: ...ce fuel injector pg 7 Bad Fuel Empty fuel tank and re fill with new unleaded ethanol free gas Loss of fuel pressure Bad fuel pump Check fuel hoses for loose fittings and possible leaks Test fuel pump pg 10 ECU Issue Replace ECU pg 8 Take existing ECU to KTM dealership for re mapping Engine cranks but does not start Bad fuel pump Check fuel hoses for loose fittings and possible leaks Test fuel pump...

Page 10: ...Check crank rod bearings pg 21 Loss of Power Excess Piston Wear Replace piston and rings pg 13 Smoke coming out of exhaust Damaged Cylinder Check and replace Cylinder piston and rings pg 13 Check oil level Engine will crank but won t start Improper Valve Clearance Adjust Valves pg 11 Engine timing off Adjust Timing pg 23 Engine won t turn over Possible damaged Piston Cylinder or Crankshaft Check P...

Page 11: ... the Seat Using your 8 mm T handle or socket remove the bolt under the rear fender as shown in Picture 1 then remove seat Picture 1 Paochow Step 2 Remove the Fuel Tank Using you 8 mm T handle or socket remove the bolt on top of the fuel tank as shown in picture 1 1 and then remove the 10 mm bolts connecting the shrouds to the front radiators Disconnect the electronic cable on the top of the fuel t...

Page 12: ...6 disconnect the fuel cable as in picture 1 2 You can now remove the fuel tank Picture 1 1 Dirt Rider Picture 1 2 Ntl World ...

Page 13: ... 360 Using your Phillips screwdriver remove part B Locate the fuel filter Part A and remove it from the plastic fitting Part C Gently place your new fuel filter into Part C Changing the Fuel Injector Tools Needed 8mm T handle or socket 10mm T handle or socket Phillips Screwdriver Phillips short socket Parts Needed Fuel Injector Part 77141023044 Part B Part A Part C ...

Page 14: ... two screws shown in picture 1 3 holding the fuel injector in place Picture 1 3 ebay After removing the bolts gently un plug the injector and Replace it with the new one Replacing the ECU Tools needed 8mm T handle or socket 10 mm T handle or socket Parts Needed Aftermarket ECU Used ECU Cannot buy a new OEM ECU ...

Page 15: ...nce and Repairs Fuel System 9 Step 1 Remove the seat pg 5 Step 2 Remove the ECU Locate the ECU picture 1 4 located behind the fuel tank Gently unplug the Main connection and replace the ECU Picture 1 4 Rubber Side Up ...

Page 16: ...ump Step 1 Remove Seat pg 5 Step 2 Test Pump To test the fuel pump tap the electric start once and you will hear the pump turning for 3 seconds or more If the pump turns for less than 3 seconds then it needs to be replaced ...

Page 17: ...ed 8mm T handle or socket 10mm T handle or socket Feeler Gauge Parts Needed Valve Shim Kit Step 1 Remove the Valve Cover Using your 10mm socket remove the three bolts holding the valve cover in place as shown in picture 1 5 Then remove the Valve cover Picture 1 5 Motorcycle com ...

Page 18: ... clearance for a 2012 KTM 250 SX F is 18 23 thousands of an inch If you cannot fit the 18 into the gap then you need to put the next size smaller shim in If you cannot fit the 23 into the gap then you need to increase the valve shim size Below is a picture to assist you in the process Picture 1 6 SM Junkie Rocker Arm Valve Shim ...

Page 19: ...eep socket 27mm deep socket Flathead screwdriver Parts Needed 2012 KTM 250sx f Piston Kit aftermarket or OEM Cylinder Head Gasket Kit aftermarket or OEM Step 1 Remove the Valve Cover pg 11 Step 2 Put the motor on top dead center TDC The first thing you need to do is remove the large Screw in the center of the stator cover Picture 1 7 Picture 1 7 Dirt Rider ...

Page 20: ...e 1 8 the Motor is on TDC Picture 1 8 Kevyorks Now that the motor is on TDC we can lock the crankshaft so that the motor cannot turn while we are disassembling it Below the water pump on the right side of the motor you will find a bronze hex screw Using your 13mm hex key remove the screw Then remove the washer and put the screw back in You may have to turn the motor back and forth a few times to g...

Page 21: ...ket remove the timing chain tensioner from the front of the motor After removing the tensioner the timing chain will now be loose Proceed to step four Step 4 Replacing the Piston Now that the motor is locked on TDC we can begin the disassembly Start by taking off the rocker arm Timing Chain Tensioner ...

Page 22: ...alls Next you need to remove the wrist pin clips using a flathead screwdriver Picture 1 9 Picture 1 9 Dirt Rider After removing the wrist pin clips you can push the wrist pin out Now you can remove the piston and replace it Work through the steps backwards to re assemble the bike It is crucial that you secure the wrist pin in properly Make sure that the clips are back in the grooves completely Onc...

Page 23: ...s as shown in picture 2 Picture 2 Motorcyclists Online It is also crucial to make sure that all four valve shims are in place Now lift the timing chain up and over the two timing gears and make sure that the timing marks are facing each other as in picture 1 8 Follow the steps on page 22 to set the timing Then tighten down all of the bolts to the proper torques which can be found on page 24 ...

Page 24: ...et 13mm hex key 15mm deep socket 27mm deep socket Flathead screwdriver Dial Bore Gauge Step 1 Removing the Cylinder Follow steps one and two for replacing a piston on pg 13 and pg 14 Once the motor is on TDC remove the bolts holding the cylinder in place Gently lift the cylinder off of the piston Picture 2 1 Enduro 360 ...

Page 25: ... of an inch difference from top to bottom If the taper is any more then the cylinder has excessive wear and needs to be replaced Step 3 Checking the Cylinder for Damage Checking the cylinder for damage should only be necessary if smoke is coming out of the exhaust dirt was sucked through the intake or after a motor problem To check for damage simply look for scratches on the cylinder If any scratc...

Page 26: ...d screwdriver Step 1 Remove the Piston Follow all of the steps on pages 13 16 to remove the piston Do not replace the piston Step 2 Checking for Wear The rod will be as shown below in picture 2 3 without the piston Picture 2 3 All Things Moto To check if the crank rod bearing is bad grab the top of the rod and try to move it up and down If there is Crank Rod ...

Page 27: ...the piston Step 2 Unlocking the Crankshaft In order to check the main crank bearings the motor will have to be taken off of TDC To do this locate the hex screw underneath the water pump on the right hand lower side of the motor Remove the bolt so that the crankshaft can rotate freely Step 3 Checking for Wear Now that the crank can rotate freely grab the top of the rod shown in picture 2 3 and star...

Page 28: ...g each other then the timing is correct If not proceed to step 4 Step 4 Remove the Timing Chain Tensioner pg 15 Step 5 Reset the Timing To set the timing correctly loosen the camshaft bridges slightly then lift the chain and spin the gears until the two golden marks are facing each other Step 6 Reset the Timing Chain Tensioner The 2012 KTM Tensioner is oil fed but can be reset so that the timing d...

Page 29: ...Technical Data Engine Tightening Torques 23 Picture 2 4 KTM 87 ...

Page 30: ...24 Picture 2 5 KTM 87 ...

Page 31: ...ew_ktm Digital Image http i ebayimg com t KTM250SXF KTM250 SXF KTM 250SX F 250SXF THROTTLE BODY NEEDS FUEL INJECTOR TPS 5 00 s JPG Digital image Enduro 360 Baja Parts n d Web Digital image http homepage ntlworld com p dezeeuw ktm_ Digital image http img photobucket com albums v280 KevInYo rks 250FtensionerTDC jpg 950sm_maintenance ht m Digital image http images motorcycle usa com PhotoGallerys 12 ...

Page 32: ... 30313 KTM 690 SMC 2008 Detail Digital image http www supermotojunkie com showthread php 76471 690 SMC valve check adjust pics questions Digital image Paochow Simple Machines n d Web KTM 2012 250 SX F Owner s Manual Brochure Mattighofen Austria Author 2012 ...

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