The KTM 300XC-W TPI isn’t that different from a conventional two-stroke. We’ve been dealing with fuel-injection for over a decade now on four-strokes, and the rest of the bike offers no real technological differences from a bike in the late ’90s. In response to a large number of requests, here are my top 10 maintenance tips for the bike.
KTM 300 TOP 10 MAINTENANCE TIPS
1. Bleed forks: Air bleeder screws should be bled before every ride. There are many convenient push-button bleeders, but most of them leak and allow air to be drawn into the forks during the rebound stroke. Air pressure makes the fork harsh on small trail trash. I use STR bleeders.
2. Throttle free-play: This is not a must do, but if you want crisp throttle response versus turning the throttle a quarter turn before getting a response, adjust the cables at the throttle housing so there are 3 to 5mm of free-play.
3. Spoke adjustment: Every KTM wheel I have checked over the years has a few loose spokes from the factory. If left unchecked, it puts excessive strain on the other spokes and causes premature spoke failure.
4. Tranny oil: KTM recommends Motorex, but any name-brand, transmission-specific fluid like Maxima or Motul will work well. Some budget-minded guys use 10w40 automotive oil, but those oils lack polymers that cushion the gears and clutch plates. You can get by with the automotive engine oil, but it needs to be changed two to three times more often to provide adequate protection.
5. Brake fluid: It’s difficult to assign a time or mileage interval, because the service interval is dramatically affected by the type of use. For the average weekend warrior who is not hard on brakes, annual service is fine. Guys riding hilly/mountainous terrain should change their brake fluid three to four times per year. Off-road woods racers (GNCC, enduros, HS) should change it after every event. Use a high-temp DOT 3, 4 or 5.1. Never use DOT 5 silicone-based fluid. Motul 660 is my favorite.
6. Air filter: Single-use throwaway filters are all the rage in air filter maintenance right now. I’m not a big fan. Same with spray-on filter oil. It’s convenient, but I’ve seen many engines damaged from the lack of protection. It’s not tacky enough and usually not enough is applied. Grease the sealing surface? If it makes you feel good, do it; but all it does is make a big mess.
7. Fuel filters: There are two filters, a large one in the tank and a small one in the fuel line. The small inline filter is easy to inspect and easy to clean with compressed air. The much larger in-tank filter is difficult to inspect. KTM says to change it at 40 hours, but I think 80 hours is more sensible.
8. Top end: Although KTM says to replace the piston assembly at 10 to 40 hours, 100 to 125 hours is a common service interval. I replace mine at 80 hours because I like to keep the power crisp. Some guys go 200–250 hours. Replacing rings alone is not recommended.
9. Clutch: KTMs have excellent clutches. If you don’t abuse the clutch, like by getting stuck in an axle-deep bog, it will last forever. I’ve seen them with 500 hours and still in good shape. Other than requiring regular tranny fluid changes, clutches are typically maintenance free.
10. Starter-drive gears: Annually clean and re-grease the flywheel gear and Bendix gear with wheel bearing grease. The Bendix body should be lubricated with a silicone spray. The gears and Bendix are located behind the ignition cover on the engine’s left side.