[madrob1]

Hey everyone, I'm brand new here and wanted to share my first sumo project.

I've been dreaming of building a 525 sumo bike since I got my first KTM back in 2001 (400 exc). About 4 years ago a chronic pain issue forced me to stop off road riding and racing. I really missed having a bike so this winter I decided to turn lemons into lemon aid and go sumo. I spent a few months looking for the right bike and finally found my ride. It's 2006 525 EXC in really good condition with 99hrs on it. After I bought it I discovered that this bike used to belong to a good friend of mine. In fact, I wanted to buy it from him a few years ago but it wasn't good timing for me. The result is I found the exact bike I wanted for this project.

Here it is as I bought it. Sorry for the poor photo but the next ones will be better quality.

 

[Pinepig]

You're going to love it, they make really good sumos. I love mine.

 

[EndGame]

Looking forward to the build!

 

[madrob1]

Ok, I have to admit I got way ahead of my thread and rode the bike yesterday. I like it!

So, with all used bikes there are a few issues and the first one I found was the steering head bearings were shot. I decided to finally buy some nice tools so I picked up this little item. It made installing the new bearing races so easy that it only took me 10 min to remove the old races and install the new races.

 

[madrob1]

After pricing out aftermarket wheel sets I decided to go with the factory KTM sumo wheels with cush drive. The factory KTM stuff was not a lot more than the cheapest aftermarket I could find and I knew they would fit and I like using as many factory parts as possible.

I ordered the 5" wide rear rim (they have 4.25" also) and put on a set of Heidenau super wets. I wanted something with a little grip for off road and still sticky on the road. Not sure how long they will last but they were a good price so I had to give them a go. Also went with a 44 tooth rear sprocket.

This rear wheel was a little tricky to install. First, I cut the protruding ends of the chain guide bolts flush with the chain guide. Next, the rear brake pads must be removed and then the wheel can be installed with a bit of wiggling.

 

[madrob1]

For electrical, I ordered a wiring harness for the UK version of the 525/450 as they came stock with turn signals, horn, rad fan, etc. I didn't get any pictures of this part but it was a very easy swap out. I ordered a KTM 500EXC left side switch but it was too large and interfered with the clutch perch so I picked up a left and right switch from Sicass Racing. They plugged right in and freed up some bar space.

I know these old KTM's can be twitchy so I ordered a new mount kit for my Scotts damper and bolted it up along with my Flexx bars. I've had 3 wrist surgeries and cannot ride offroad without them. They are pricey but I've had this set on 4 bikes now and they are still straight after many crashes. My old hand guards were interfering with the headlight so I need to come up with a new solution.

What's to come? I have a 320mm front rotor and caliper bracket on KTM back order so that will bring the front end together. I also am waiting on some KTM turn signal connectors to get the front signals hooked up. I'll likely get an SMR header pipe for better silencer clearance along with a nice Akrapovik silencer down the road.

 

[madrob1]

Ride report

It feels perfect!

It accelerates and brakes on tarmac really well and it will be even better with the larger front disk. I do think it might be geared a little tall with that 44 tooth rear sprocket. I'm barely off the idle circuit while doing 100kph in 6th so I think it can do with a 46 tooth rear. This will also make it a little easier to wheelie as right now I need to hit the power just right.

Now for those tire. They feel great on the road but amazing on grave roads and even trails. I was able to go about 75% of my normal trail speed. This was dry conditions and I would not want to try this in muddy conditions but it's great to know I can explore trails when I feel like it.

What to do next?

- Get a lower and more comfortable seat
- new handguards
- SMR header and Akropivik silencer
- larger fuel tank

Yesterdays ride was really nice and much needed after spending a week in severe pain. It's only a couple times a month that my pain level is low enough to ride but now I've got the perfect machine for it.

Cheers!

Rob

 

[TuffGong]

What are the KTM part numbers for the wheels that you ended up using?

 

[madrob1]

What are the KTM part numbers for the wheels that you ended up using?

Here yah go! Keep in mind the damper blocks come individually so you need to order 6 of them. I was surprised when only one showed up.

Part Number: 5841000144430
Description: REAR WHEEL 5,00X17" BLACK

Part Number: 5840900164430
Description: FRONT WHEEL 3,5X17" BLACK 26MM

Part Number: 58310050044
Description: % SPROCKET SUPPORT CPL. (superceeded)

Part Number: 54610459000
Description: RUBBER DAMPING BLOCK `91

 

[madrob1]

So it turns out running a dead battery is a bad idea. I was just using the kicker to start it and figured it would be fine. Well, yesterday I took the seat off and found the battery top was cracked and leaked acid. Luckily, the only damage is to the air filter as it seems a little acid dripped on it.

I've ordered one of those Earthx batteries so that should solve the issue.

 

[madrob1]

more parts

Got some new parts in, just waiting for the KTM caliper bracket.

 

[Tfunk]

I agree on the chain slider bolts.... I actually swap them for a conical heat and turn them around and a small countersink and they are even better flush.

Yes the cush drive stuff can be a PITA to install compared to the solid RFS hub, the rear on the SMR comes right on and off rather quickly. But I wish I was running cush out on the street cause it does cut down on the vibes......

 

[madrob1]

season is over

So I ditched the headlight mounted turn signals and installed a set of Zeta handguard deflectors with integrated turn signals. I like how stealthy they are.
This winter I plan to:
-install an FCR41.5 carb
-change cam
-do the ground float stator mod for more DC power
-upgrade headlight cause the stocker is crapola at night
-make some proper spacers for the front fender (using plywood right now- lol)
-install axle sliders (I want to do a track day next year)
-install KTM carb vent line drip can
-do something about the seat

I only put 9hrs on it this season but it made me smile every time i got on it.

 

[madrob1]

winter projects

Along with the work mentioned above I have two other projects this winter. I finally have a complete set of NOS plastic (other than tank) and graphics for my 86' KTM 250 MXC so I'm doing a frame up restoration and engine overhaul. The other project is a 77' Honda CJ360T that I just picked up. Gonna do a cafe/scrambler kinda thing with it. It's my first bike with a metal tank!

 

[mwm13]

Love the bike man I have pretty much the same one, tires and all. Been trying to track down a part # for a black front fender and headlight plastic but it seems alot of its back ordered and my universal fender looks like trash compared to stock stuff! Nice work!