THE ULTIMATE BIKE BUILD
2023-25 KTM 300 SX / XC
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This build also applies to HUSKY 300 TC / TX - This does not apply to the XCW / TE models.
It's March 3rd, 2025. I've had this KTM 300 since 2023 and it hasn't seen much dirt. Most of it's life has been indoors on the dyno. Up until now, I've spent little time on this bike in the dirt, for than main reason that I live in a little town called Sequim, WA, in the pacific northwest.
The problem with testing here, is, that it's mainly tighter stuff, where you don't get past third gear and half throttle. I understand that, this type of riding is apealling to many, but I hate it. I mean hate it. I ride in it a lot for testing purposes, but I also complain about it to anyone in earshot.
So a lot of my time is spent indoors, developing stuff and then sending it out to great test riders I work with, for real world feedback. It's all been real good and everyone happy, but finally I'm heading to Az, to the warm fast desert, to test it all for myself.
The things I will be discussing are the components that add up to the dyno improvemet seen here.
The yellow line is the stock bike when I bought it, and the red line represents the gains achieved with all the parts and ecu reprogramming that can purchased on bestdualsportbikes.com.
There are quite a few videos on the Pinit Racing youtube channel which will help you with all of this as well. Not all of it will be on this page, just the key parts.
If you were to do one thing to any TBI bike, it would be to replace the stock, cheap, rubber crankcase pressure sensor holder, with this better one we make. It fixes all the problems with the stock ones leaking and also the sensor positioning is much better.
The leaks change the pressure readings to th ecu, and that makes the bike run richer or leaner than normal, creating all kinds of ghost problems for you.
In addition, the upright position of the sensor now keeps oil from clogging the sensor's membrane, like it does with the stock position. This keeps the bike running crisper everywhere. Get this part.
The second thing you'd do to any TBI bike is replace the "reed stops" with the "reed strips" we sell. You can see the reed stops in the picture with the black curved plastic piece holding the reed down. The other photos show the 2 strips alone and the strips now installed in place of the stops.
They are flexible fiberglass, and simply put, they just let the reeds open much more easily, by lowering it's tension at throttle openings below 1/2 throttle.
They provide a nice gain in throttle response and power. And many people have given the same feedback on them.
"That's a huge gain for only $20 and did a lot more than a $300 pipe did!"
At this point I can't suggest it strongly enough to replace your cheap, weak, crappy stock battery, with a great one. For one, it's the ONLY way you have to start the bike. If it turns to slow, the bike just won't start and you are stuck. Rarely will they even bump start.
So COVER YOUR BUTT and don't walk home or die in the middle of nowhere.
Also, the extra power these put out will increase throttle response a bit right off idle and into the midrange. You get 2 wins for one low cost.
Here you see a potential problem with the 23-25 300's. Not just the SX / XC bikes, but the XCW bikes as well. That is, that the intake skirt of the piston can, and many times does, hit the crankshaft, when the rpms are running really high.
You can see how I cut the bottom of the intake skirt up 2mm on the pistons I sell. You can see in the other pic, the black arrow showing where the skirt would touch the top of the crank half.
This would really only occur, if you are revving the bike hard and even more so if it's hot. Like a fats moto track on a hotter day. if you are riding below 3/4 throttle, it's really not a concern.
If the piston does hit the crank though, that thing is going to scatter. So if you are going to get a new piston, you may as well used one that's cut.
I have the real Vertex pistons and also the forged Wossner brand pistons available.
Now for the biggest power gain. Since we've covered how to fix the primary weak links, and the easy power gains are done, lets start making some real power! I'm talking about our ecu remapping.
A lot of continual work has been put into this mapping. A lot of the gains are made with controlling the power valve opening times and rates. This gets the bike up and going sooner and pulling harder.
After that, the ignition timing get's fixed. Ignition timing affects throttle response and power, but also affects the air fuel mixture. Once you get the balancing act of fuel and timing figured out, then hold on.
The result so far is a harder pulling bike in all gears from idle to top, and it's crisp.
Our ecu mapping is the only stuff out there with a 30 day satisfaction guarantee. So try with confidence.
At this point, many people add the billet fuel rail. It's one of the biggest selling items. Reason is, the stock plastic one like to break off at the neck. This happens when you try to undo your fuel line quick disconnect fitting.
Then you are stranded. This was such a problem, that you couldn't buy a stock rail for months at one time.
We also increased the size of the holes, since wide open testing showed the small stock hole size caused the bike to lean out after a few seconds.
You need to remove the throttle body from the bike, to change this, and you do not re use the clips on the injectors
BUY NOW
The flexible idle screw you see below, is normally added when the throttle body is off for the fuel rail. It's long enough to where you can easily get to it, for quick idle changes. Also, the XCW and TE models, don't like to have thier idle speed increased sometimes and this screw opens the throttle plate further, to be able to increase the idle
buy now
Now let's add more power. Stronger, more responsive bottom end to be exact. The 2 parts below are designed to do just that. The larger volume exhaust valve cover you see, with the PINIT logo on the side of it, is a big seller.
It's designed to add more volume to the exhaust chamber, which works when the exhaust power valve is closed. From idle, to about half throttle, the exhaust power valve is closed. This is when this chamber is open.
We have 2 products that really help in this department. The oversized exhaust valve cover and the TBI Grunt exhaust manifold.
The cover, is a simple bolt on that basically doubles the volume inside the chamber area. It takes the volume of liquid held from 2 oz to 3.5, just for reference sake
This increases the
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