KTM rebuild

[carl_g]

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:

[ronin_01r1]

take lots of pics! GL.

[NYCSTRIPES]

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.

[bondo]

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:

[bondo]

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.


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.

[NYCSTRIPES]

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:

Powerseal does nice work. They replated the barrels on my TZ250 this spring. I am pretty happy with the quality of the work.
Ken

[Ant]

Yeah Carl!

[carl_g]

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:

[NYCSTRIPES]

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

[carl_g]

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
The crank is getting sent out to this guy in KY. He goes by the name of Mr Crankshaft and he has been super helpful and there has been excellent communication.

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

[NYCSTRIPES]

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

[carl_g]

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
paper gasket..

[John712]

oh man, and i though my bike was in pieces!

[Ant]

why are the rear cylinder bolts corroded?

[NYCSTRIPES]

probably from a coolant leak..just a guess.
Ken

[carl_g]

why are the rear cylinder bolts corroded?
Good question... I have no idea. I have seen pictures of other people's ktm's torn down and noticed similar corrosion on the rear bolts as well :huh:
I will clean them up but I am not going to replace them.

[carl_g]

Cleaned the head up tonight.. it was too damn hot to do anything else...

http://www.ism409.com/images/ktmrebuild/rebuild_19.jpg

[John712]

Damn looks nice and new, what did you use to clean it?

[carl_g]

Damn looks nice and new, what did you use to clean it?
Elbow grease, carb cleaner and a couple of scotch brite pads. :)

[FigNewTon]

Cleaned the head up tonight..
Nice work man. Damn thing looks new.

[carl_g]

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. ;)

[NYCSTRIPES]

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

[carl_g]

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
No I don't have to grease them.. they get their lubrication from the oil in the premix. I might put some 2 smoke oil on them before I put it together so when I first start it there is already some oil down in there... the other bearings towards the back of the case get lubed by the gearbox oil. :)

[carl_g]

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:

[bondo]

the pic of the mushed needle bearings is cool :roflmao:

more pics!

[carl_g]

the pic of the mushed needle bearings is cool :roflmao:

more pics!
Here is a couple more.. ;)
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

[SAXON117]

Here is a couple more.. ;)
I got the crank back into the cases and put them back together.
Before mounting the lower end of 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


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:

[carl_g]

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:

[duc748pilot]

good job dude! glad everything worked out!

[NYCSTRIPES]

cool!

[JimRBlue]

I had fun reading along with the progress story. congrats!

[Respect_My_Authorita]

nice work carl :D