Bolt It On Bike Rack

I just got a new Mercedes Sprinter van and I don’t know about you, but when I spend the kind of money I did with my new van, I want to make sure my bikes are secure and not going to fall over and ruin the sides of my new Sprinter. After I sold the ol’ trusty 2016 Sprinter, I purchased our new 2021 version and was looking for a bike rack to secure my test bikes. Some of you may be asking why not just build out the back of the van Kris? Well, it’s called money and I seemed to have spent a lot of it when I got the new van so I can’t exactly afford to build out a custom van right now. After doing some research, I wanted to try a different bike rack company than the previous one I used, so I decided on Bolt It On. Bolt It On is a family owned and USA operated business out of central California. After scouring their website and the tons of options they give you, I decided on the three dirt bike kit with 60 degree chocks with a 4 inch middle chock for my 170 sized van box. 

Installation literally took me 10 minutes and required zero tools. I began by locating the long square tube known as the crossbar. This is the body/base of your rack. I began by loading the chocks onto the crossbar, then installed each support leg as well as a tie down hook on the inside or outside of each support leg. Lastly, attach one j-hook on the left and one on the right of the corssbar. Each j-hook should line up through a hole positioned directly above each D-Ring. That is it! Boom! Done. No tools required! What’s even better is that the whole system feels and looks quality. No crappy welds or burrs, the cuts on the crossbar are clean and even the paint on the kit has a nice finish to it. 

Initially I was going to install the Bolt It On rack to the D-Rings directly behind the bench seat but noticed that the crossbar stuck out over the side door step so we relegated the crossbar to the  set of D-Rings that are set back one row. After speaking with Scott (the owner of Bolt It On) he mentioned that they offer a shorter 144 box version of the crossbar that can be installed directly behind the seat, which will not affect the clearance of the step. So, if you’re in the market for a bike rack from Bolt It On, make sure you kind of know where you would like to install it before making your purchase. Loading bike into the chocks is easy and what I like most about having that 60 degree bend is that the bikes we load up will not sway back and forth when tied down. In my previous van I had another bike rack that had chocks that were straight and had some nightmare-is moments with the bars hitting the sides of my van when hitting bumps in the road (no matter how tight we got them). Adding a third bike through the middle was a breeze and even though we mounted the Bolt It On rack back a little inside the van, we still had enough room to throw in toolboxes, gear bags, gas cans, etc. 

The benefit to this Bolt It On rack is that I can disassemble and reassemble in minutes if need be. I don’t have to drill into the frame of my rear bench seat and my bikes are more secure with the Bolt It On rack, with the 60 degree angle of the chocks! Bolt It On makes these bicycle and dirt bike racks for all different makes and model trucks/vans and if you want a custom crossbar size, Bolt It On can cut the bar to your specific size. You can visit them over at boltiton.com or call Scott at 805 975 8280. Prices range from $400-$500 for a complete 2-3 dirt bike kit.  If you have any questions about this test, please feel free to email me at kris@keeferinctesting.com.

Questions About Av Gas Answered

A Bit of Information About Aviation Fuel

Aviation Fuel has been used as a low-cost substitute for high octane fuels for decades. This was more common in the hay days of 2 strokes, due to higher probability of detonation, and thus the change to 4 strokes has seen a decline in the popularity of “aviation race gas”. The reason for aviation fuel, once all the folk lore is stripped away, is simple; The most common aviation fuel (100 Low Lead) has a high-octane rating, is low cost compared to store bought race gas, and has a higher resistance to detonation than pump fuel. The relatively high (compared to pump gas) octane rating is achieved using a chemical tetraethyllead (TEL) (the lead in leaded fuel) which increased the resistance to detonation.

Detonation in an aircraft is a very bad thing. Imagine sticking a ring at 8000 ft, makes Mt. St. Helens look like an ant hill when you fall from that high. In a motorcycle, especially a two stroke, the balance of compression ratio, cylinder temp, air/fuel ratios, and the like can push a machine to the limit of detonation. A two stroke seems to love life at the edge, a 125 seems to run the best right before it stops running completely. An increased octane rated fuel resists detonation more than a lower octane rated fuel. This is the definition of the octane rating, notice the lack of power in that definition. A father of an aspiring 125 champion could make a high compression, lean running, crisp feeling engine, and run practice with Aviation fuel to lower the fuel bill. The fuel by no means produced the same power, throttle response, or any of the key characteristics of a good running machine, but it would allow the bike to run with a longer service life for less money.

Octane Rating

I used the phrase “octane rating” earlier. This was chosen instead of phrases like: “the octane in the fuel”, “has more octane”. Octane is a physical molecule, has physical properties, even has a very easy chemical formula:

Octane = C8H18

However, in modern applications, octane is not what makes a fuel more or less powerful, more or less resistant to detonation, or better or worse race fuel. The “octane” in a fuel is a simplification of “octane rating”, which is a test of the amount of compression alone that will cause fuel to combust. I will briefly describe the test, to hopefully clarify what the number means, and make clear that “octane rating” does not correspond to increased/decreased engine power.

Octane Test:

If you take pure octane (C8H18), vaporize it in air, and compress it rapidly, eventually it will combust on its own. This is equivalent to detonation in a real engine, in that there is no spark required to start combustion. You can do the exact same test with heptane (C7H16) which is similar in chemical composition, physical properties, but it will self-combust at a lower pressure than pure octane.

If you blend octane and heptane with a ratio of 50 parts octane and 50 parts heptane, the mixture would have an octane rating of 50. This is the definition of the octane rating. The mixture would self-combust at some pressure given the test described above. Any fuel mixture (diesel fuel and pump gas, 50:50 race gas and pump gas, vegetable oil and nail polish) that self-combusts at the same pressure in this test would have an octane rating of 50. You can imagine these mixtures would make different powers, but the fuel would have identical octane ratings. 

Octane ratings are independent of power output.

Most pump gas has an octane rating of 87 to 95 depending on where you live. This means that the fuel coming out of the “87” hose at the gas station will self-combust at the same pressure as a 87:13 mixture of octane to heptane. The pump does not, however, pump out pure octane and pure heptane in that ratio. The fuel we buy is a mixture of near countless chemicals designed to meet environmental, storage, transportation, and performance requirements for the lowest possible costs. I will skip the rating methods and different octane numbers based off the test, but just know that the number on the pump in Europe vs the US does not tell the whole picture. Crossing international borders makes comparing fuel octane ratings difficult due to laws that govern what goes into that number on the pump.

 This may then beg the question: “What is 110 octane rated fuel, you can’t have 110% of something in a fuel”? This is true, and the simple answer is the rating is just plotting self-combustion pressure past 100% octane test fuel. The chart below illustrates this.

Back to Octane Rating:

The octane rating is crucial, as it allows a consumer to know the fuel they are purchasing will not cause damage to the engine by detonation. One of the more practical ways to think about octane rating is the amount of energy needed to start the combustion process. This energy comes from 3 main sources, each adding on top of one another to eventually reach the threshold to start combustion. The main sources are:

1. Engine Temperature

The hotter the fuel is when entering the combustion chamber, the less energy needed to get the fuel to combust. Likewise, the higher the temperature of the components that make up the combustion chamber, the less energy required to start combustion. This is due to the thermal energy in the hot engine parts transfers to the fuel while the fuel is in the engine, waiting for the spark. These no doubt play a role in meeting the minimum combustion energy level, but if you pour gas on a piece of metal at 1.5 times the temperature of the cylinder walls, it will not self-combust. The temperature of the incoming air and temperature of engine parts can push an engine near detonation over the limit, but typically cannot combust fuel just by touching it.

Compression:

This is the main perpetrator in detonation, and the main reason why people think race bikes “need” high octane race gas. When you compress any gas, the temperature goes up. Do this fast enough, and the increase in temperature can be substantial. If you have a can of compressed air, you can run this process in reverse. Spray the can against a piece of material and the air leaving the nozzle is ice cold (never point this at someone as it can cause frost bite even through clothes). Compressing air is the exact same process in reverse, so heat is generated rather than lost (exothermic vs endothermic for the nerds out there). The more you compress air, the more energy that is generated. Compress it enough, and enough energy is generated to combust the fuel without spark. This is the main source of energy when detonation occurs.

One additional note: compression is not uniform in the combustion chamber. The shape of the combustion chamber has a drastic effect on detonation risk. This comes from some areas of the head getting very close to the cylinder head, and the air struggles to move away fast enough when at high RPM. This causes local high pressure areas, which causes local higher temperature, which can push a small amount of fuel over the combustion limit. A small area detonating can spread the flame to the whole air fuel mixture, causing complete detonation. 

This is part of the reason why a two stroke on the limit will have some small damage at the edge of the piston when running correctly, the pressure is highest, and some small detonation happens, pitting the surface. This is also why you typically only get detonation at high RPM. At low RPM, there is enough time for the air to have a more uniform pressure (and the heat generated by compression can bleed out through the cylinder). Without local high pressure spots, detonation is less likely.

Spark Plug:

In a perfect engine, the spark is the last little bit of energy needed to start the combustion process, which is where you get the power from an engine. I won’t delve too deep into this, but just know that the spark is designed to start combustion in the center of the combustion chamber to allow for an even, non-damaging, pressure wave. When detonation occurs, it is typically not at the center, very uneven, and causes much higher cylinder pressures than what the engine was designed for. Lastly, a cooler or hotter spark plug is used to give a little extra energy for quick, even burning. A hotter plug means the porcelain piece is physically at higher temperature due to some design differences. The increased temperature, like cylinder or air temp, can be enough to push the engine into detonation.

There are many, many sources that engine designers consider when developing an engine for power character, running temperatures, RPM ranges, etc. that all factor into how the combustion process occurs. A paper on these items would be a great PhD thesis, and more than any sane person would be willing to read. These 3 are the simplest, and are the largest contributors to detonation risk.

In simple terms, a higher number octane rating means a higher energy level needed for combustion. When doing any engine modifications, you need to consider these factors and consider higher octane fuel if some change (typically compression ratio) will push the machine into detontation risk. You do not, however, get more power from higher octane fuel. In a stock machine, switching to a high octane fuel can sometimes decrease engine power output.

A Brief Word on Combustion

Combustion is very complicated when trying to design parts to optimize power. The concept governing it is simple. The commandments in the bible of power are rather simple:

“Get as much air and fuel, in the right ratio, into the cylinder as possible.”

“Thou shall not detonate”

“Achieve the maximum possible cylinder pressure as soon after Top Dead Center as possible”

The first comandment is for another conversation. The second we have already talked in detail. The third is what seperates the men from the boys, the cats from the dogs, and the good fuel from the bad. The power in race gas is the way that it builds pressure in the cylinder, increasing the power. Again, I want to make it clear that this is not because of the octane of the fuel. The simplified principle is that race gas burns quicker than standard pump gas. The faster a fuel burns, typically, the lower the octane. Defying this trend is what you pay for in race gas. 

When fuel is too high octane, combustion starts later than it should (because the energy requirement for combustion is not met until more cylinder pressure is built up) and the burn rate of the fuel is slower. The chemical properties that make a fuel resistant to detonation also make the fuel burn slower once the combustion has started. An engine in a motorcycle is just a mechanism that turns pressure (from fuel combustion) into mechanical motion. If the pressure of the cylinder is high, it gets the engine moving faster, and making more power. If the fuel takes a long time to burn, the pressure is lower, and less power is generated. 

Final Thoughts

There are a lot of extra pieces to this puzzle, but for simplicity, this is what fuel designers must balance.

1. Fuel needs to not combust prematurely (detonate), so an octane rating is needed to achieve this. Some bikes need 110 (turbocharged drag bikes), some bikes need 100 (modified two strokes), and some bikes need 93-95 (4 strokes, modified and standard).

2. Fuel needs to combust in a controlled, consistent manner so that cylinder pressure can be very high on the power stroke to get maximum power from each molucule of fuel. This is used for efficiency on road cars, and power in racing aplications.

3. Fuel needs to have an appropriate cost for the application. Pump gas makes some sacrifices in area 1 and 2 to achieve a cost. Race fuels sacrifice much less, but have a price that goes with it.

I hope that this offers some clarity on the complex liquid that is fuel. When buying fuel, you need to be realistic about your application needs, your desired cost, and have realistic expectations for what to expect when you pour it into your tank. 

1. Don’t fall into the misunderstanding that the “octane” is in the fuel, or that you can add octane out of a bottle. 

2. You don’t always need the highest octane for every application (sometimes it can undo power gains you probably paid good money for). 

3. Octane rating does not cause power. Filling up the 1998 E350 with 91 won’t help my quarter mile time.

4. Race fuel cost what it does for a reason. It is high quality, engineered fuel that will actually give you power (not from the octane rating though).

Taking it Back to the Start, “What about av gas, is it good?”

Av gas, like any specialty fuel, is great for it’s application. It resists detontation, resists evaporation at low pressures (8000 ft), and is a decent price. However, av gas is designed for planes that run at 2800 RPM, not 14000, so it burns slower, and unless you have some wicked step up skills, the fuel evaporation probably won’t be a problem. If you have a two stroke that is detonating, I would ask yourself 3 things:

1. Do you need the compression ratio you are running? 

2. Is your jetting right? You may need to richen up a bit to get the ‘ol race YZ490 to sing all day.

3. Don’t you work hard to play hard? Treat yourself to some high quality fuel, designed for motorcycles, with the appropriate octane rating. Don’t forget the last commandment of power (and first of lunch meat):

“Compromise Elsewhere”

Scosche PowerUp 700 Portable Jump Starter

I usually stick to dirt bike related things on this site, but since I recently used the Scosche Power 700 Portable Jump Starter on Lil D’s (Donnie Emler Jr.) brand new 2019 Husqvarna FC450, I thought I would give you guys some insight on why this is a great piece to add in the truck, car or van. The 700 Portable Jump Starter is a high-capacity 15,000mAh lithium-ion battery w/700 amp peak that can jump start vehicles up to 10 cylinders, is spark-free, and the 6-point safety protection system prevents any unwanted mishaps. It also has dual 5V (2.1A + 1.1A) USB ports for charging mobile devices, has a safety protection against any short circuits, a reverse connection/Polarity, ultra-bright LED flashlight, 1000+ charge/discharge cycle backwards that is compatible to work with smaller engines and the LED battery power level indicator works just fine on cars, trucks, boats, ATV/UTV’s and of course dirt bikes.

How many times have you messed around with jumper cables, only to have the positive and negative touch? With most other portable jumpers on the market, you can cause a short circuit and permanently damage the unit when those clamps come in contact. Plus sparks can be dangerous to you and the vehicle as well. The Scosche PowerUp was designed with Spark Proof technology, allowing you, your vehicle, and the unit to stay safe should the clamps touch. My wife doesn't like to jump start anything because she is intimidated by big jumper cables, but with this Scosche 700 Jump Starter, she feels safe enough to do it on her own! Boom! Score! 

What about when it’s dark outside and you need some extra light? This unit has you covered, with the built-in ultra-bright LED, you're provided with plenty of light to find your battery terminals, find your phone (in the loads of crap under your seat), in your carry bag or wherever you may need it. The LED also has a strobe and SOS flashing option just in case you’re in distress or want a portable rave unit.

This Scosche 700 also includes many other great features such as the ability to use it as a backup battery for mobile devices. Low on battery life and your kids are hogging the cords? No problem the Scosche 700 provides you with one 2.1A and one 1.1A USB ports so you can charge two devices at once! 

Most importantly it saved my buddy Lil D’s butt as his new Husqvarna FC450 waste charged enough to start. I simply whipped out the Scosche 700 Portable Jump Starter and the white beast fired right up. He let it idle for a few minutes and the battery was ready to rock! It also takes up almost zero room in your cab and I rarely have to charge it.

Go check out all the products Scosche has to offer at scosche.com and use the code SCOKT25 to save yourself 25% on almost every product on their site! 

VP MR-Pro 6 Racing Fuel Review

If you're on a budget and are happy with your pump fuel, just continue on with your day and don’t worry about this review. There is nothing wrong with pump fuel (unless you’re from California then you have ethanol problems). However if you do have some extra cash and want to see an improvement in your engine’s power delivery, continue to stick around and read all about VP’s MR-Pro 6 racing fuel. MR-Pro 6 is an unleaded fuel engineered to generate maximum horsepower in four-stroke applications while still conforming to the AMA rules for lead and oxygen content. MR-Pro 6 delivers more power (than pump fuel), thanks to its carefully formulated oxygen and octane content. It requires some jetting/mapping changes and also require some changes in ignition timing. This unleaded fuel is said to make the equivalent power of leaded MR12 on the dyno.

I have been testing the 2019 KTM 450 SX-F and 2019 Yamaha YZ450F a ton lately with aftermarket ignitions. With these ignitions you are able to have increased parameters and can really tune in a bike’s power delivery. To aid in some of this delivery, race fuel becomes very important, so I have been using VP’s MR-Pro 6 in both machines. Now before I tell you how it performed with these aftermarket ECU’s let me start off by saying that you “should” map your ECU for MR-Pro 6, but for testing purposes, I tried the VP fuel with a stock ignition without a re-map. By simply pouring in the MR-Pro 6 into your stock steed, you will see some benefits like increased throttle response and more bottom end. However if you're spending anywhere between $130.00-$180.00 a pail, you will want the most out of your money. Simply pouring this stuff into your bike isn't going to blow your mind with its performance on the track. Don’t waste your money! 

If you want to really benefit from VP’s MR-Pro 6 get your stock or aftermarket ECU re-mapped for this type of fuel. Once mapped you will feel all of the benefits of some good race fuel. You will notice you will have even more RPM response, bottom-mid range pulling power, and an increase in peak horsepower (over-rev). Even with a stock ECU (that is re-mapped for MR-Pro 6) I get all of these positive affects, but with less top end/over-rev. 

Our 2019 KTM 450SX-F test bike has lived on MR-Pro 6 for the past 20 hours or so.

With a GET or Vortex ECU and MR-Pro 6 the difference is huge on the track. I have spoke about the importance of ECU settings and what they can bring to modern four-stroke technology in my podcasts. It’s huge! MR-Pro 6 gives you an increase in horsepower everywhere on the track and gives your four-stoke a crisper throttle response that makes your machine feel slightly lighter feeling on the track. Yes, fuel with an aftermarket ECU CAN DO THIS! 

One downside to the MR-Pro 6 is that it can boil when the temperatures rise. I had better luck in the summer months with ETS Racing fuel than I did with MR-Pro 6. You will notice if the fuel starts to boil because you will feel the machine start to run dirty (or rich) feeling (and you will lose a lot of throttle response). In the winter months or on cooler days I have had no problems with MR-Pro 6 boiling. ETS was just more consistent when the temperatures were high. 

If you're looking for increased horsepower and throttle response, VP’s MR-Pro 6 is a huge advantage over many other unleaded race fuels out there. Just be sure to store it somewhere away from your living quarters because the MR-Pro 6 is pungent. The smell is quite strong and can really make your wife or neighbors mad.