Boring KTM Rebuild Thread

[El Camexican]

I like to torque the swing-arm/motor mount bolt first, then the lowest motor mount and then move my way up to the upper mount, or head stay.

I believe this is the most critical mount of all and is probably under more stress than any other besides the swing-arm pivot.

This particular mount should be shimmed and not just reefed into place.

On this engine & frame example there was almost a .040” gap on the right hand side of head after the upper upper bolts were torqued to the frame.



Using the nearest flat washer to the size I needed, a grinder and a magnetic holder I managed to make the appropriate shim without losing too much skin from my finger tips.





Southern engineering to the rescue!

[El Camexican]

I have a pet peeve regarding these bikes that relates to the way that the pipe connects to the spigot on the cylinder.

The manual shows two O-rings and every rebuild kit comes with them, but there’s nowhere for them to go that makes any sense. The result is that no matter how much silicone you use when mounting your pipe, it doesn’t take more than an hour or so of riding before signs of spooge leaking out around the spigot are visible.

This is what a stock speak it looks like and what the pipe looks like when it’s placed over it..





I decided to try welding a ring around the existing spigot that would leave a groove open for one of these O-rings to fit inside. The donor part is a factory unit that I bought brand new a few years ago and while doing a leak down test found out that the factory weld was leaking, so it needed some weld anyway.









This is what it will look like when it is connected to the new pipe. Hopefully the O-ring won’t split.

[Red Rider]

I'm pretty sure you're supposed to wrap a rag around the spigot/exhaust junction to contain the spooge, and then the 2 o-rings hold the rag in place.

Your fix looks nicer though. I hope it works for you as planned.

[El Camexican]

Forgot to post this up....

These carbs have a reputation for dripping fuel when ridden over rough terrain. I’ve tried a few things like crimping the tip of the tip of the tube inside the float bowl, bending it upward and raising the float to lower the fuel level in the bowl, but this little trick I found on a bike site is a much easier fix.



You just route the overflow hose to loop just below the top of the main jet orifice which is well above the top of the internal overflow tube.

This isn’t a big deal for somebody who races motocross, or rides30 minute loops between Gatorade stops on their tailgates, but it’s a huge deal for anybody who is trying to get 100+ miles out of a tank of fuel when crossing the desert.

[El Camexican]

Given that the bike’s nickname is Mad Max I figured a little sinister bling was in order, so I scuffed down the pipe guard and rad protectors and dropped them off with some other parts that needed plating for some black anodizing.





Figured it would out last powder coating and can easily be redone in the future.

[El Camexican]

For some reason KTM decided to use a larger diameter spigot on the cylinder head of this bike than the plastic Y fitting which diverts coolant into the two radiators. No big deal, but they used a length of rad hose that fits tight on the head and loose on the plastic fitting. It works, but I can always smell antifreeze in that area when the bike gets hot and it just isn’t right.



So I went to “Vatozone” on the weekend and found a hose that transitioned almost perfectly between the two diameters. Problem solved.

[El Camexican]

Time to put the new pipe on. First we mount the modified spigot and new mounting tabs on the frame.

Next we spray the inside of the pipe inlet with some high temp engine enamel (color’s not important) this is a poor mans substitute for thermal ceramic coating and prevents the nickel plating from discoloring when the pipe gets hot. Works better than you might think. I also put a bit of silicon on the flange in case my o-ring modification fails.







Also installed the recently played foot pegs.



Notice anything different? That’s right, aftermarket cotter pins! Is this thing trick or what?!?!



Always trim or bend your cotter pin ends out of harms way. Drastically lessens the odds of bleeding while maintaining your ride.

[El Camexican]

So last night I thought I would finish this project up.

Started by replacing the scuffed up hand guards.





Ain’t dat purdy?

All that was left to do was tighten up the sub frame, put coolant into the rads and mount the tank, shrouds and seat.

As I began to pour coolant into the radiator I noticed that there was a dripping sound coming from underneath the bike. My first thought was that I had forgotten to tighten one of the hose clamps, but that “duh” moment quickly turned into a “WTF?” moment when I realized that all the fittings were tight and the coolant was spewing out of the base gasket at the front of the engine almost as fast as I was pouring it into the rad.

I have no idea what could be causing this, but I will need to completely remove the engine in order to find out as this particular model was not built to accommodate a top and rebuild without an R&R. It sucks and is one area (besides e-start) that makes the newer stuff very appealing.

I won’t be able to touch this thing again until mid August when I return from my annual fishing trip. I sure hope it’s something simple that I can laugh about later.

[Red Rider]

I sure hope it’s something simple that I can laugh about later.

Bummer dude, but it's turning out sweet so far! Most likely, it's the Continuum Transfunctioner that's leaking. Pretty common issue on these KTMs.

[El Camexican]

Well, mystery solved and lesson learned. The next time I think I’m so darn good at this that I can skip the pressure test I will remind myself of this screwup.



I assume I snagged the base gasket on the cylinder liner while sliding it into position. I vaguely remember having to force it a little bit while thinking that it was the O ring around the power valve rod that I was struggling against.

No matter, it’s all cleaned up and back together.

[Red Rider]

Is that real phosphorus predator blood inside your motor?

[El Camexican]

Is that real phosphorus predator blood inside your motor?

Motul 2 stroke oil and Prestone pre-mix. Apparently the two combine to become a decent anticorrosion fluid. Had I used straight water in the rad I’d be in quite the pickle.

[El Camexican]

It would seem that the boring rebuild has morphed into a boring rebuild and makeover.

With our annual ride 120 miles to Cuatro Cienigas, get piss drunk, sleep, get piss drunk again and then wake up and drive 121 miles back with a killer hangover (I added one mile for the weave factor coming back) I was forced to prep the other bike which needed 2 tires, a new rim and a Lectron carb as well as some TLC so it cut the line on Mad Max and got some love this weekend.

Started with replacing the cracked and bent rim and then the rubber.



Feel free to show this next photo to the next person that tells you dirt bike wheels don’t need to be balanced cuz it’s true, they don’t, especially if you like riding a pogo stick over 40mph.



And now the bling as I was finally able to find some white replacement shrouds for Piñata bike. These are rarer than hens teeth on this side of the pond.



I’m getting better at putting decals on. Now instead of them looking like I did the application myself it just looks like I paid some that isn’t very good at it.

[Maico]

What pegs did you use? Looks like those may be some tasty treats for my '92 550 rat restore.

[El Camexican]

What pegs did you use? Looks like those may be some tasty treats for my '92 550 rat restore.

Forged steel IMS from RMATV. They come bare and rust fast, so I had them blasted and plated.

You might also want to look at a set of TUSK aluminum units. My buddy just picked up a set and they are sweet. Price is only a couple bucks over the steel pegs.

Tusk has really gotten aggressive on price and quality lately.