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banana4monkey

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Reply with quote  #1 
I put the 2003 KTM 450EXC on the lift last night. First off this bike is great. It is basically a street legal motocross bike that is a blast on the street, motocross track, woods, and seasonal roads. I bought the bike used and I am hearing some noise coming from the bottom end. I am not sure the exact location even using a mechanics stethoscope. I plan on disassembling the entire motor, inspecting the parts, and replacing the worn parts. This bike did not have a original odometer on it or an hour meter so I am not sure what the usage is on this motor. I put the bike on the lift and the first task was the rear brakes. They stopped working for some reason towards the end of last season. I bled the brakes and it solved the problem. Next job is to do a compression test as a baseline, drain the fluids, and start taking the motor apart. It's nice to start on a new project. My goal is to have it done by the end of the moth. This will be highly dependent on what I find. If I have to send the crankshaft out for rebuild I will be at the mercy of the vendor.



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New project on the lift

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Bleeding the rear brakes using the mighty vac and adding fluid the rear brake master cylinder

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MR. X

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Reply with quote  #2 
Nice,i look forward to following along. Let me know if you need to send anything out ,i can get you in touch with Dan ,he has lots of time tearing in to modern 4strokes and has some solid info as well as good contacts.
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banana4monkey

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Moving forward on the KTM… First I wanted to mention that it’s a good idea to look at the service manual before you do the work. It can give good tips as to what sequence to do things and it lets you make sure you will have all the tools you need for the job. I know that I may not have a flywheel puller for this machine so it was my goal to get the left side cover off and check it out. Also it is good to stay organized. I used some old wood and a bodyman stand to make a table for all the small motor parts.  See pics below for progress.

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Makeshift table for motor parts

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Service manual out and ready

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Drain engine oil

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Drained coolant and removed radiators

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Removed flywheel cover and I do not have the right puller. Ordered the puller from a shop on e-bay for 18 bones. Hopefully this won't slow progress down.



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banana4monkey

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This weekend I removed the rocker covers, camshaft, and cylinder head. The cam chain needed to be removed using a chain riveting tool as seen in the pictures. I found that the intake camshaft lobe shows some wear. The camshaft will need replacement. I am starting to put together parts list and researching replacement part options. This KTM has a nice feature of locking the engine at top dead center. See pics below for more detail. Next will be removing the top end.

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exhaust removed

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carb removed

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swingarm removed
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This bolt when the washer is removed fits into a notch in the crankshaft at top dead center. This feature makes it nice so you don't have to hold the engine in place by other means.

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water pump cover off

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rocker cover off

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removing the cam chain with the chain breaking tool

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damage to the intake lobe of the camshaft

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cylinder head off

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banana4monkey

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Flywheel puller is in so I removed the flywheel. With the cylinder head off there is enough clearance to get the motor out of the frame. This motor is in there tight but I got it out and placed it on the workbench. Next I took the cylinder off. The cylinder and piston look good visually but I will need to do some measuring to verify. The connecting rod side to side play seems to be a lot but then again I will have to disassemble it further and take some measurements.

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Flywheel puller installed.

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Flywheel removed

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Motor on the bench

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IMG_4554.JPG 

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banana4monkey

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More disassembly. Removed the following - piston from connecting rod, cam chain and guides, right hand cover, and clutch pressure plates. No visual problems found with the parts that were removed. The connecting rod seems to have a lot of end play on it though.  I need to buy a two jaw puller so I can get the cam chain sprocket off of the crankshaft.

Note that I used a cardboard template for the side cover bolts so I don't mix them up due to their different lengths.

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MR. X

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Reply with quote  #7 
Looks good so far , you and i have been doing the bolts in the cardboard since the gt80/xr75 days. I hear all the professionals just take all the bolts out and put them in a coffee can in no particular order.
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banana4monkey

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Reply with quote  #8 

Time is tight this week but I spent about an hour working on the KTM motor. I finished disassembling the clutch and moved on to the primary gear. I didn’t have a 2 jaw puller that fit so I ended up using a flywheel puller to pull the primary gear off.



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Clutch removed

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Holding primary gear with clutch holding tool

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Using flywheel puller to remove primary gear off of the crankshaft

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Primary gear removed

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banana4monkey

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Almost to the point where I can split the crankcases. I removed the kickstarter assembly, external shift mechanism, oil pump, starter, and oil filters. I removed the crankcase bolts but I can’t split the crankcases until I get a small 2 jaw puller to remove the cam chain sprocket that is attached to the crankshaft. Next will be getting the gear off, splitting the cases, removing the crankshaft, balancer, and transmission. I am hoping to have the disassembly complete this weekend.

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Kickstarter off
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external shift mechanism removed

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Oil pump removed

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Oil filters. I use the reusable stainless steel type.

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Lots of parts on the table waiting for cleaning and inspection. 


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banana4monkey

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Reply with quote  #10 

Engine disassembly is complete. I got my 2 jawed puller in and removed the timing chain sprocket off of the crankshaft. After this I split the crankcases and removed the transmission and the crankshaft. It is important to take good notes and pictures so they can be used on reassembly. Note the use of rubber bands to keep the transmission and shift forks together.  Now that the motor is all apart time to move on to cleaning and inspecting all of the parts.



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