AN URBAN EXPLORING ADVENTURE IS BETTER ON SUPERMOTOS!

MY RIDE: 2003 KTM 525 EXC SUPERMOTO

I picked up this gem of a motorcycle at the end of 2017. It is a 2003 KTM 525 EXC RFS with 160 hrs on the original engine. It ran well and from 20 feet away was in perfect condition. I bought the bike for under $3000. The main selling points were that the engine had never been opened, it was one owner bike, had lots of enduro engineering hard parts, was a 6 speed, street plated, and ran/shifted smooth. It was a little difficult to start so I started by adjusting the valves and rebuilding the carb. The JD Jet Kit was the first mod and it was well worth it.  No more starting issues and less bog off the bottom. I rode the bike a couple of months before really digging in. Replacement of all cables and bearings were the first changes. The bike is a daily commuter and I wanted bulletproof. Having an engine that was over 15 years old and never opened made be nervous but also confident that there would be no surprises during the rebuild. The process took way longer than I had planned with a variety of issues. I outline them below. The bike had lots of engine noise which the internet will lead you to believe this is normal. IT IS NOT! Trust me. Now she is dead smooth and silent.

Below are a few common causes of engine noise.

KTM RFS Engine Noise Culprits:
1. Loose crankshaft nut
2. Bad cam chain tensioner
3. Bad clutch bearings
4. Bad rod bearings
5. Bad main crank bearings
6. Piston Slap
7. Loose auto decompression screw on the cam (Use Loc-tite)
8. Carb slide plate: If you hear a rattle that sounds like a chirp the throttle slide is often the culprit. Once diagnosed it can be left alone. To check, touch something against the slide while running. The noise never goes away but as long as the seal is good and the plate is not upsidedown then you are good. All FCR carbs do this.
9. Loose cam chain or bad chain tensioner. Make sure your chain tensioner is not out of travel. If it is within 5 or so clicks replace it and the chain. I replace my tensioner with a manual one.
10. Skid Plate – Skid plates amplify all engine noises even if they are rubber mounted. They still make mine sound horrible so for 90% street supermoto I do not have one installed.

Mine was a victim of most of the causes above. The rod and crank bearings were fine at first but when I rebuild the top end I installed the head gasket I ordered for a 525 but was sent a head gasket for a 450. I failed to check to ensure the fire ring did not stick out into the cylinder. Spoiler, it does and does impact the piston. The bike started and rode great but was a little loud. It continued to increase in volume so I pulled it back apart and found the piston had turned the fire ring on the gasket into a razor blade. Round 2 rebuild begins with a replated cylinder, new 12.5/1 piston, new rod, and complete bearing replacement in the bottom end. Lesson learned. She is super quiet now. Meh

KTM 525 Free Mods:
Cut airbox cover
Cut front & rear fenders for Supermoto
Remove Return Throttle Cable

Tips for RFS owners:
1. Run your chain lose, really lose. All bikes are different. Depends on sprocket sizes. To set perfect jack bike up and remove rear shock. pivot swingarm up and down by lowing and raising jack. The chain will be the tightest when the swingarm is parallel. At the chains tightest point it should still have a little play. Tighten your tensioners and put the shock back on. Then with the bike on the kickstand cut a piece of plastic or wood that can go between the chain and swingarm behind the top chain slide. Now you have a block that will tell you how tight your chain will be on the kickstand. You will need to redo if you change sprockets.
2. Learn to adjust your pilot fuel screw. (With the bike warm and idling turn the fuel screw in till the bike bogs. slowly back out the screw till the bike is at its highest idle and stop. That’s the amount of fuel it needs. No more and no less. In is Lean and Out is Rich. If the bike pops on deceleration try backing out a little. It could also be an exhaust leak.)

Build Breakdown:
Warp9 17″ Supermoto Wheels – Bought used but wish the rear was a cush hub.

Front Tire – Avon AV79 3D Ultra Sport 120/70ZR17

Rear Tire – Continental ContiMotion 150/60ZR17

Enduro Engineering rear disc guard

Neoprene fork covers

Vertex High Compression 12.5/1 Piston – Can still run premium fuel just fine

Wrapped header

Chain and sprockets (14/42 is perfect for 4th gear power wheelies but is very highway capable)

Moose fanny pack modified to fit as a tank bag. Any fanny pack will do.

Motion Pro Coolant Overflow Bottle

DJH Manual Cam Chain Tensioner

Highline Recreation Tugger Lift Strap, Rear – Click to get from Rocky Mountain

JD Jetting Jet Kit – Click to get from Rocky Mountain

Tusk Clutch Kit – Click to get from Rocky Mountain

Tusk Motorcycle Enduro Lighting Kit – Click to get from Rocky Mountain

Tusk High-Pressure Radiator Cap With Temperature Gauge – This is a higher pressure cap. Helps with coolant loss. – Click to get from Rocky Mountain

Mylers Silicone Radiator Hose Kit – Click to get from Rocky Mountain

Twin Air – Air Filter – Click to get from Rocky Mountain

Tusk Billet Aluminum Gas Cap – Click to get from Rocky Mountain

Clarke Oversized Fuel Tank (3.1 gallons) – Click to get from Rocky Mountain

Neutron Gripper Seat Cover – Click to get from Rocky Mountain

Odi V2 Rogue MX Lock-On Grips – Click to get from Rocky Mountain

Cycra Probend Alloy Bar Pack Handguards – Click to get from Rocky Mountain

Tusk Folding Shift Lever – Click to get from Rocky Mountain