60 Hours and Counting On Our Orange Thumper
Story by Trevor Hunter, Action Photos by RevD Photography, High Clicks Media
We just cracked the 60 hour mark on our 2020 KTM 250 XC-F project bike, and they’ve been a tough 60 hours at that. We started the year off racing the AMA National Grand Prix Championship, but as COVID-19 struck, that came to a halt. Since then, we’ve been hammering away doing motos and testing quite a bit with a couple of SRA GP’s mixed in as well. Without further adieu, here’s what we have learned in the nine months and 60 hours of owning this bike.
Maintenance wise, it’s been pretty basic up to this point. We change the oil every 5-7 hours, with an oil filter change every other oil change. Maxima’s 10w50 ProPlus+ is our oil of choice and it’s held the motor together quite well. The only other maintenance we’ve done to the motor is replace the valve cover gasket. It started leaking around the 20 hour mark, so we replaced it and it started leaking again after another 20 or so hours of use. Instead of replacing it, we used some silicon around the edges and the leak is gone.
With 60 hard hours on the motor and it being a 250F, we felt it was time to dive into the motor and replace the top end. From now through the end of the year, we’ll be racing this bike quite a bit and will have little time to do any big maintenance items in that time. The top end change is relatively simple on this bike. You can do everything without removing the motor from the frame which is a plus. Getting the head off is a tight fit, but it goes on and comes off when taken out though the right/pipe side of the frame.
The piston and rings all looked really good for the amount of time on it. In reality, it could go a little longer worry free. The wrist pin looks to have the most wear and tear on it, but still nothing to be overly concerned about. Since we went in with the objective of replacing the piston and rings, we installed a Vertex GP Racer piston. The kit includes a piston, rings, wrist pin, circlips, and all of the necessary (and some unnecessary) gaskets for a convenient kit.
For the most part, installation isn’t all that difficult given you know what you’re doing on a four-stroke top end. We struggled a bit getting the rings lined up and the cylinder over the piston, but once aligned a certain way, it slipped right on. Now, we also made one other crucial mistake. REMOVE the dowel pins from the cylinder when reinstalling the cylinder! We didn’t and one fell into the bottom end when fumbling around with the cylinder. Typically, this wouldn’t be a huge deal; however, in an effort to save weight, KTM made these out of aluminum which kept us from digging it out with a magnet. Our next steps were to drain the oil, flip the bike into a nose wheelie, then flip the bike completely upside before it fell out. Ultimately, we didn’t have to pull the motor or split the cases, but it made for a longer (and two-person) night in the garage.
Our FMF exhaust has held up quite well in the 50+ hours we’ve put on it. The stock packing still looks really good for the amount of time on it, and aside from the faded stickers and scratching on the canister, the exhaust is in really good shape.
For tires and mousse’s, we’ve primarily relied on Maxxis Tires and Nitromousse’s, though we’ve been playing around with some Kenda Washougal II and Millville setups as well. Our Nitro’s have lasted quite some time, with over 30 hours on a set. At that time, they started getting too soft and let the tire roll more than we preferred, but we can get some more life out of them by cutting and inserting some wedges. One thing we’ve had trouble with on this bike is keeping spokes in the rear wheel. We’ve gone through 15+ spokes in the rear wheel using both a stock 18″ XC-F wheel, and a 19″ SX-F wheel. On our 2019 250 XC two-stroke, we never had an issue with spokes breaking or really even coming loose, including on the 19″ SX-F wheel, but this bike has proven different. Dubya USA trued our wheels and slowed the breaking of the spokes down, but we still come across a broken one every few rides.
All of the bearings are solid on the bike. We greased everything when brand new, and have since regreased every bearing at 30 hours to be safe. In addition, the throttle is getting a little sticky and stiff to twist, even when lubed. We have a new set of OEM cables that will take care of the problem. Brake pads, we’ve used EBC rear pads to help combat our heavy right foot. They work well in that they aren’t super touchy and they last forever, though they are really loud. We’ve gotten 30+ hours out of the EBC’s whereas we would typically get 5-6 hours out of the stock pads. The clutch on this bike is on its way out, having trouble disengaging when cold. But, we feel safe in saying we got our money’s worth out of it having 60 hours on it, though we aren’t heavy clutch abusers. We have fibers, steels, and the rubber grommets on order and expect it to last the lifetime of the bike.
Our Chain/Sprocket combo was pushed a little too far, especially the chain, and we stretched 45 hours out of the Mika Hybrid Sprocket/Sunstar MXR1 chain. The sprocket held up well, but the non o-ring chain had lots of play by the end. We sent it through one mud race which took its toll and decreased its life prematurely. In the last month or so, we upped the gearing from 13/51 to 13/52 for our MX/GP style riding. The KTM motor is very dependent on maintaining high RPMs to go fast, and adding one tooth to the rear sprocket helped close the gaps between gears and make nailing shift points a little less critical.
Overall, the 250 XC-F has held up great in our time with it. Very little maintenance is needed, and all of the bits and pieces have avoided wearing out. We’ve had to do very little to keep the bike running smoothly other than tires, oil, and air filters. Stay tuned for a durability test on the Vertex Piston Kit that we just installed, along with some interesting suspension mods we’ve been testing and fine tuning all summer long.
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