Full Disclosure 3: 2018 Big Buck GNCC on a 300 XC ATV!

Full Disclosure 3: 2018 Big Buck GNCC on a 300 XC ATV!

I’m working on the article where I detail the whole build and that will be coming soon, so I won’t rehash that here, but suffice to say the off-season was pretty nuts from my perspective. We got the 300 together faster than I expected, but not as fast as we really needed to, and coming into the Big Buck GNCC, we only had about 4 hours of jetting work on the quad and about 45 minutes of ride time in the rocks in Kentucky, so I really hadn’t even tried it in any real XC terrain yet.

While riding in Kentucky, I did experience a bit of a knock on deceleration. Research on the internet and talking with a couple of folks who are big names in the KTM 2 stroke world, it certainly seemed like this knock was very normal. From what I understand, particularly with the high compression head and the SXS CDI, all of them do it, but it is widely regarded as harmless. You can’t jet around it, and the only fix is to go to race gas, but from what I’ve read and been told there’s really no reason to do that as the knock only happens on deceleration and doesn’t seem to cause any problems long term.

I went to Big Buck knowing that the knock was there, but confident that it wouldn’t be a problem.

Friday Afternoon:

Racer Productions offered a practice session Friday and I decided to take advantage of it at the last second. The first lap, I was immediately blown away with what the 300XC was capable of! On the pipe, it is extremely quick! The KTM 450/525 ATVs already handle very well, but with a loss of around 35 lbs and a serious focus on mass centralization, the 300 is even better! It seemed like I was able to carry significantly more corner speed than usual, just because it can change direction quicker and with less effort.

It’s worth noting that it was a cool day when we were riding in KY, and it was a bit wet, so I wasn’t really hammering on things like I was in the near 80 degree heat Friday. I suspect that’s why we didn’t know how bad the knocking really was, because within a lap of trying to ride at a sprint pace, the knock started to become very significant. The fan kicked on about then too, so I knew we were reaching temperatures we hadn’t seen before. I went out for a second lap. The knocking continued. Now it was doing it any time I lugged the revs down too far, any time the wheels unloaded and the revs suddenly jumped up, and any time I free revved it on the clutch at anything less than full throttle. Basically, the only thing it liked doing was revving and banging gears.

Speaking frankly, that approach was WAY too physical to be sustainable for a 2 hour race, so I needed to address the knock. We made a quick needle change with no significant improvement, so in desperation, we hustled back to the pits to try plan B.

Knowing that the knock may have been an issue as temps came up, I brought a can of VP T4 race gas with me to SC. The reason for this was because T4 is a 100 octane race gas that’s designed as a premium pump gas replacement, so I could in theory run it without rejetting the carburetor which was something we were quickly running out of time to do. While I poured Motorex Crosspower 2T into the VP can, dad drained as much as he could out of the tank and into our premix jug. Unfortunately, there wasn’t much room in my fuel jug as I had filled it earlier Friday morning. When we got to the point that we couldn’t fit another drop in the orange jug, we put as much of the VP T4 mixed at 50:1 as we could fit into the 300’s fuel tank. We probably wound up with about a 40/60 race gas / pump gas mix.

Heading back to the practice track, I found that while the knock was reduced, it certainly hadn’t gone away, and most of the things that caused knocking before still did, just not as bad. We ran out of time at the practice loop and idled back to the truck. All I could think was that I was going to blow a hole through the piston at the first race on this bike and I didn’t know what to do about it. It occurred to me that I could just run straight T4 and hopefully that would fix it, but by this time Derisi Racing had sold out of T4, so that wasn’t an option and switching to another race fuel would mean re-jetting which we didn’t have a way to do. I went to the hotel Friday night, thinking about how best to deal with this problem in the morning.

It’s also worth noting that while I was concerned about the longevity of the engine, another significant concern was that I knew that I couldn’t hold on to the thing for 2 hours riding it the way I had been at the practice track. Frankly this was a secondary concern when I was convinced the thing wouldn’t live for 2 hours anyway, but it was weighing on me nonetheless…

Saturday Morning:

Saturday, we got back to the track by 7:30 AM. We had a lot to do and not a lot of time to do it in. I got to vendor row as the guys at Derisi Racing were starting to open the trailer and asked immediately for a can of VP T2. T2 is 105 Octane, oxygenated (presumably to a level similar to T4, but I wasn’t able to confirm that), premixed 40:1, and leaded to prevent predetonation. Without knowing how the bike would respond to the richer oil content from a jetting standpoint, or the possibly different levels of oxygenation, we opted to mix it 50:50 with the 50:1 T4 from the day before. Dad bought a blue VP fuel jug to drain our race gas mix from Friday into and we went to work.

A quick ride around the pits revealed that the idle was slightly lower than it had been on our 40/60 race gas mix, but it didn’t seem to mind the fuel, so I came up with a formula to run for the race. We ran 1 gallon of T4, 1.5 gallons of T2, and 1.5 gallons of the 40/60 mix from the day before. This brought us to right at 100 octane, with the majority of the fuel still being something I knew worked from a jetting standpoint, and almost 40% of the fuel being leaded.

As I sit and type all of this out, I know it sounds absolutely crazy, but there were so many conflicting priorities. If the T2 was oxygenated too heavily, it could make the bike run lean and we could still damage something. Alternatively, if 40:1 of whatever oil VP uses for T2 behaved much differently than 50:1 of my Motorex Crosspower, that could cause other issues. Remember, at this point we were focusing on making the bike survive, but I still wanted to be able to ride it and have a good time out there. It wouldn’t do for me to get towed back to the pits whether it was because we had blown an engine up, or because all of this fuel-related stuff had caused me to foul a plug or something along those lines.

With the fuel situation as sorted as it was going to be, I started gearing up. Probably about 4 minutes before I was to head to the line, dad pointed at a small piece of black plastic coming out from behind the tender spring on my left front shock and asked “what’s this?” As I got closer, I saw that the threaded adjustable crossover spacer had cracked and a piece of it had come out.

“This,” I replied, “is really, very bad.”

I grabbed a set of calipers and measured the crossover gap. 17.9mm. When we were testing in KY, I had originally set it at 15mm. The front end body rolled everywhere. Closing it up to 13mm had fixed it. Nearly 18mm wasn’t going to be rideable. I would probably have rather just loaded up and gone home than go out on that setup. So, we removed the shock, broke away all of the spacer that had been cracked, turned it upside down and started trying to adjust it back into spec using the bottom of the threads that hadn’t been damaged yet. Long term, this was not going to work, but I hoped it would survive the day (and it did!). With dirt from the practice day before embedded in the threads, we spent WAY too long trying to get the jam nuts to turn. Fortunately, we got it back to 13mm rather quickly once we found a way to get everything turning. We got the shock back on the bike, hurried through a few other things and then took off for the starting line.

As I rode to the line, I shook my head and laughed. I was going to blow up an engine, foul a plug, or DNF some other kind of way, and now this crossover spacer was going to break and cause me to body roll the whole time until I did. Ever the optimist…

Race Time!

The starting line was fun as the theme for the weekend of everyone doing a double take and then coming over to talk to me about what we had built continued. When the green flag flew, I got a solid holeshot and lead the class going into the woods! (Video below) I started the day being somewhat aggressive with the 300 as it had preferred that so much the day before. Unfortunately, it became obvious pretty quickly that this approach wasn’t going to be sustainable. The 300 XC engine is VERY smooth, for a two stroke. But I’ve been riding exceptionally smooth 4 stroke engines for most of my racing career and there’s still quite a surge on top when the powervalve opens up. When that happens down in 2nd or even in 3rd gear, the front end actually gets light enough to be a bit vague in steering in the tight woods.

As the day wore on, I started lugging the engine more and more, and I was amazed at the results! KTM 2 strokes make a slight whistle as they come up on the pipe. I have always assumed that it’s either the powervalve opening, or the noise of the timing device that controls that action. It has something to do with it either way and I learned pretty quick that if I heard that noise in the tight sections of the woods, things were about to get a little scary. Fortunately, the engine ran well enough down low that you still had plenty of operating range without even getting to that area of the power curve.

There was quite a bit of shifting involved in this approach as you wanted to short-shift each gear, but the revs could fall too far and suddenly require a downshift if you weren’t paying attention and planning ahead with your gear changes. Even still, I would argue that I was able to ride the track just as smoothly as I could on my 4 stroke ATVs with the added bonus that if I needed more power, a simple dab of the clutch caused the 300 to surge forward at an alarming rate! Interestingly, when I got to a field section, this approach completely changed and keeping the quad up high in the revs generated some fantastic speed in the more open parts of the track! It took some time to learn to ride the new engine, and I expended a good bit of energy in the process, but once I did, I found that it was capable of doing just about anything you wanted it to, once you knew the  rules.

Probably the single most interesting thing about riding it throughout the day was the handling. As I noted the day before, the 300 could change direction effortlessly and I found myself carrying a lot of momentum through the corners in the woods. On the whole, the light weight really seemed to pay dividends in the tight stuff, which shouldn’t have been as much of a surprise as it was.

As far as the race goes, that went well enough. I had a great start and started putting time on 2nd place pretty directly. I encountered my first 4×4 riders between miles 2 and 3 and started working my way through them. I had worked through probably 10 or so of them a minor disaster struck at mile 10.

I was following a 4×4 rather close as I was hoping to find a way by. It kicked up a long stick that was about 3 inches in diameter, which went right through my front left A arms. It smashed into my shock, pushing the spring off to the left and then out the back of my arms. I stopped immediately, running into the crossbar pad. As I looked down at my shock with it’s clearly bent out of shape spring, my first thought was that I had bent a shock. As I saw that the stick had gone the whole way through the arms, my second thought was that I had probably torn a brake line. Fortunately, neither turned out to be the case, but unfortunately, it took me a minute or so to free the 300 from the stick. When I finally got going again, I was riding with people I had passed several miles back. They were almost all 4x4s, so I had no idea if anyone in my class had got by me and focused on getting through these guys for a second time and waited to see what I learned when I went through scoring.

Nothing. I learned nothing when I went through scoring. The screen that tells you where you are in your class was down. In fact, it was down for the entire race, so I was never able to tell for sure where I was in class. As I set out on the second lap, all I knew was that I had lost significant time and had to make it up. About 2 miles in I caught a rider in my class. By mile 3, I found my way by him in a field. At that point all I knew was that at least one of them had got by me. I put my head down and pushed and never encountered another rider in the Sport class for the rest of the day.

Two miles from the finish on my last lap, there was a mud hole. It wasn’t that bad, but the line to the right that I had been taking all day was getting more and more torn up, so on the last lap I took a fresher looking line to the left. This wound up being catastrophic. As I climbed up the steep bank and out of the mud, my right rear tire found its way into a deep rut, which caused the 300 to essentially wheelie over backwards on its right rear tire. I wound up on my hands and knees in 6 inches of mud with the quad upside down in the same mud behind me. I had an instantaneous flashback…

Bonus Story!

In 2013, the first round of the IXCR series was held at the Badlands in Attica, IN on my birthday, February 24th. I had been experimenting with a few things, probably the most significant being the Hinson BTL slipper clutch so I decided to take the opportunity to test it in race conditions.

The race (predictably) was an absolute mudder. I spent a decent amount of the first lap stuck, but it turns out, so did everyone else in the B class I was running. Not knowing this, and desperate to make up for the immense amount of time I had lost, I worked my way through traffic with reckless abandon, taking some frankly stupid chances.

As it turned out, I was leading. I had no idea that was the case because the screen at scoring was down. So on the last lap, I was still completely impatient with everyone I encountered, eventually leading me to tumble backwards down a muddy creek bank after taking a super sketchy line to try to pass a lapper that was almost definitely going to get out of my way a few seconds later anyway. The time I lost trying to get flipped back over and then un-stuck cost me a win I didn’t even know I had a chance at.

Back to Big Buck!

As I tumbled backwards into the mud, on my birthday, with a sizable lead but no way to know it as the screen at scoring was down all of these things suddenly clicked with a sudden sense of Déjà vécu. (definition here) I said to myself: “Oh no. No, no, no, NOT AGAIN!” and got back up, flipping the 300 back onto its wheels quickly and then with the help of a GNCC official grabbing my front bumper, getting it up the muddy bank and running again. It took me about 3 tries to get up the bank myself on my feet, but the official held the front brake in the meantime and I was able to rejoin the race with only a few minutes of lost time.

I rode pretty terribly for the last couple of miles as my grips, seat, and gloves were completely saturated with mud. When I came through scoring for the last time, a friend congratulated me on the win. I didn’t know for sure if he was right, but I still breathed a big sigh of relief. It turned out, he was.

I hadn’t blown up the engine! In fact, the knock was basically completely eliminated by the race gas! And it had run amazing all day! The crossover spacers had held up and I had avoided completely repeating history from 5 years before by holding on to the win this time!

Five pages into this story, I’m amazed at the things that can happen over the course of the weekend. I feel like these little articles will get significantly shorter throughout the year, if for no other reason than because I won’t be riding on Fridays, finding problems, and then scrambling to get them fixed!

Either way, even with all the craziness Friday, it was a GREAT first weekend on the 300 XC ATV!  I can’t ask for a lot more than to win in it’s first outing.  I’m excited to have the chance to ride this thing for the 2018 season and can’t wait to see what new and exciting stuff I learn about it at the next round!


  • The 300 LOVES to be lugged in the woods. I was in 3rd gear for probably 90% of the woods at big buck, with dabs down to second to exit corners and even occasional stints in 4th! Short shift it and it will be smooth and provide great traction, if you need more, bump the clutch BUT be sure you have it pointed where you want it to go if you do.
  • The suspension was good. I’m not going to say perfect, but it was very good. I only got 1 kick all day at the end of a field when I hit a ditch I could have easily avoided. I’m not sure anything else would have handled that hit a lot better to be honest.
  • Coming into the race, I had decided to go back to a stock 300 XC head and CDI. Now I think I’m going to stick with the SXS stuff for the time being, and just run race gas. The torque the 300 makes in current trim is amazing and I’d rather not give that up.
  • The morning track is pretty fun. As the year goes on, I have several friends that are supposed to be bringing their 250R’s out to play too! I can’t wait for that!
  • 4x4s aren’t that bad about getting out of the way except that I don’t think most of them can hear me! My little 300 is so quiet compared to a 4 stroke, especially those big CVT things. I had to learn to rev at people coming into corners and yell just to make sure they knew I was back there. More than once I had someone turn and look quickly as if they were surprised and wondered where I had come from.

Holeshot video:

BIG thanks to everyone who makes it possible!!!

I couldn’t do any of this stuff without my mom, my dad, and my girlfriend Nicole, along with All4Racing, AOMC, COR Moto Graphics, FASST Company, GBC Motorspors, Hinson Clutch Components, IMS Products, KLIM, Leatt Protectives, Motorex USA, Rath Racing, Rocket Ron Racing, Schumacher Race Works LLC, Scott Spots, Streamline Brakes and Controls, Towne and Country Real Estate, Twin Air, Walsh Race Craft, and Works Connection

9 thoughts on “Full Disclosure 3: 2018 Big Buck GNCC on a 300 XC ATV!”

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