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KTM rebuild
I know it is not a sportbike, but nonetheless it is my bike and 2 weekends ago I blew up the bottom end during a race.
I need to split the cases and replace the crank. I will also replace the piston and rings while I have it all apart. Here is my progress so far of taking off the top end. Head (needs to be cleaned up) http://www.ism409.com/images/ktmrebuild/rebuild_1.jpg Engine http://www.ism409.com/images/ktmrebuild/rebuild_2.jpg Cylinder & top of piston http://www.ism409.com/images/ktmrebuild/rebuild_3.jpg Power valve actuating arm http://www.ism409.com/images/ktmrebuild/rebuild_4.jpg Cylinder - doesn't look bad at all! http://www.ism409.com/images/ktmrebuild/rebuild_5.jpg Another cylinder shot. http://www.ism409.com/images/ktmrebuild/rebuild_6.jpg This weekend I will split the cases so stay tuned for more.. oh yeah wish me luck :LOL: |
take lots of pics! GL.
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What controls the power valve?
The head gasket design is very similar to the TZ50 I have. Personally I wish it was something more substantal than these little o-rings. |
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Looks good Carl.
I guess you could consider it a little "unplanned maintenance" There's a lot of hours on that bottom end and a fresh engine will be nice to have next time you are 20-30miles into the woods. I think I might start carrying a buddy tow rope too. :ride: The guy who parked next to us at the Curly Fern was the owner of powerseal. They did my cylinder. Behold :nod2: :roflmao: |
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Hey Ken, Centrifugal force and 3 different springs with a screw adjuster. You can adjust the power/exhaust valve to operate any way you'd like. Tune the power so it's just right. O-rings are simple and it's all you need with relatively low cylinder pressure/heat. I like 'em! If it was a turbo I-4 drag bike, then some nice copper/bronze head gaskets with metal o-rings machined into the block are necessary. |
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Ken |
Yeah Carl!
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I have been sort of lagging on this project while waiting for parts to come.
I made some good progress last night. Here you can see I took off the main clutch case cover and took apart my autoclutch. http://www.ism409.com/images/ktmrebuild/rebuild_8.jpg I also pulled the flywheel and stator off.. http://www.ism409.com/images/ktmrebuild/rebuild_9.jpg I will have an impact wrench tonight to get the primary gear off and then I will finally be able to split the cases and send out the crank to be rebuilt. Thank god for friends having extra bikes with the willingness to let you beat on them :lol: :ride: |
who's rebuilding your crank? Local?
With the TZ250, all you need to do is wedge a penny into the primary gear and you can use standard tools to loosen the nut. From the angle of the picture I can't tell if that's possible with your bike. Ken |
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Here are some pics of my progress tonight.. finally the cases are split! Engine out of the frame.. http://www.ism409.com/images/ktmrebuild/rebuild_10.jpg another engine pic... http://www.ism409.com/images/ktmrebuild/rebuild_11.jpg Make sure you read the shop manual :lol: http://www.ism409.com/images/ktmrebuild/rebuild_12.jpg BAM! Split cases. http://www.ism409.com/images/ktmrebuild/rebuild_13.jpg Inside of left half of engine. http://www.ism409.com/images/ktmrebuild/rebuild_14.jpg The reason for all this work..bad crank. http://www.ism409.com/images/ktmrebuild/rebuild_17.jpg Inside of the right half of engine. http://www.ism409.com/images/ktmrebuild/rebuild_18.jpg |
looks like you're on your way. the mr. crankshaft website claims a quick turn around...hopefully you'll be back in business quickly. Question..the green stuff on the engine case...is that a rubberized or paper gasket ? or is that silicone?
Ken |
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oh man, and i though my bike was in pieces!
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why are the rear cylinder bolts corroded?
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probably from a coolant leak..just a guess.
Ken |
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I will clean them up but I am not going to replace them. |
Cleaned the head up tonight.. it was too damn hot to do anything else...
http://www.ism409.com/images/ktmrebuild/rebuild_19.jpg |
Damn looks nice and new, what did you use to clean it?
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New main crank bearings installed
Was able to remove the old seals and bearings for the crank and replace them with new ones. I had to heat the case halves to about 150 degrees with a propane torch.. after that, the original bearings fell out. I then took the new bearings which were in the freezer overnight and they dropped right into place :ride:
http://www.ism409.com/images/ktmrebuild/rebuild_20.jpg http://www.ism409.com/images/ktmrebuild/rebuild_21.jpg Cranks comes back today.. I should have the bottom back together tonight. ;) |
I used a similar trick when putting on the timing chain or my 66 Mustang...cool.
Nice and clean...looks ready to get it dirty again. do the bearings require grease or will the gear oil suffice? Ken |
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Got the crank back!!!!!!
new crank is all fresh thanks to MR. Crankshaft
http://www.ism409.com/images/ktmrebuild/rebuild_22.jpg another crank shot http://www.ism409.com/images/ktmrebuild/rebuild_23.jpg This is the old rod.. you are not supposed to see any gap there.. this thing is toast. http://www.ism409.com/images/ktmrebuild/rebuild_24.jpg You can see the bearing was starting to attach to the rod. http://www.ism409.com/images/ktmrebuild/rebuild_25.jpg I'll be putting this in tonight! :nod2: |
the pic of the mushed needle bearings is cool :roflmao:
more pics! |
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I got the crank back into the cases and put the bottom end back together. Before mounting the engine back into the frame, I fixed my outer clutch basket. It was grooved pretty bad which would catch the clutch plates and never let it fully disengage. For example, it would slightly creep on me in 1st gear with the clutch pulled in and it was also hard to kick over while in gear. I have to mill off a couple .001" or so to get the basket all smooth again. This should be good for another season or two. For now, it also saves me $200 (price of a new one) Here are the pics of the refreshed basket. http://www.ism409.com/images/ktmrebuild/rebuild_26.jpg http://www.ism409.com/images/ktmrebuild/rebuild_27.jpg |
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don't know it its my computer but I can't see those last 2 pix :( lol must be my computer after I quoted your entry they showed! :LOL: |
It Lives!!!!!!!!!!!!!!
I totally slacked on taking pics of putting it back together but it is back together and on Saturday it started up 2nd kick!!!! :drink:
I rode it the piss out of it on Sunday! - new parts/crank rebuild = $600 - new tools = $50 - hours spent working on it..I lost count - paying ZERO for labor and rebuilding the whole engine by myself....PRICELESS!!!!! :nod2: |
good job dude! glad everything worked out!
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cool!
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I had fun reading along with the progress story. congrats!
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nice work carl :D
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