• There are a few key things you should to check before every ride.
  
• Check air pressure prior to every ride
  
• Make sure the valve stem has not spun; if it has, deflate tire and re-set
  
• If riding in a rocky area or track, make sure to look between the knobs for cracks or cuts to the tire carcass
  
• Check spokes at this time
  
• Ensure rim lock is securely tightened
  

Proper inflation is key to the life and performance of your tires. Refer to this chart for correct amounts.

• Hard Conditions: Front- 12.5 – 13.5 psi
  
• Hard Conditions: Rear- 14 psi
  
• Intermediate Conditions: Front- 12.5 – 13.5 psi
  
• Intermediate Conditions: Rear- 14 psi
  
• Soft Conditions: Front-12.5 – 13.5 psi
  
• Soft Conditions: Rear – 11-12 psi
  
• Minis- 13 – 14 psi
  

For motocross tires, Dunlop changed to the industry tire standards in the same manner as street tires. However, because of the prior variations in actual dimensions, some adjustments in vehicle application have been necessary.

• When motorcycle tire standards for width, diameter and load capacity were introduced a few years ago, they didn’t include motocross tires. As a result, motocross tires varied in dimensions from one manufacturer to another. Most tire manufacturers marked their motocross tires with a size designation that related to tread width.
  
• In current tire standards, the designation for width is actually the section width, measured at the sidewall, not at the tread. This has always applied to street tires. A 4.50-18 street tire, for example, would have a section width of 4.50 inch, and would fit on an 18 inch rim.
  
• When metric tires were introduced, the aspect ratio was included in the size marking. A 130/80-18 street tire had a section width of 130mm, and an aspect ratio of 80 percent. This means that the height of the tire is 80 percent of 130mm. As before, the tire fits on an 18-inch rim.
  
• For motocross tires, Dunlop changed to the industry tire standards in the same manner as street tires. However, because of the prior variations in actual dimensions, some adjustments in vehicle application have been necessary. An off-road machine that previously fitted a 4.50-18 or 130/80-18 under the non-standards markings, now fits a 110/100-18 under the new standards. These tire sizes share the same actual dimensions. A 130/80-18 is 110 mm wide in section width and, furthermore, the section height is also 110 mm or 100-percent aspect ratio. Hence, a 130/80-18 under the new standards markings is designated a 110/100-18.
  
• With the introduction of 19 inch motocross sizes, it was necessary to reduce the aspect ratio in order to maintain the same outside diameter. To compensate for the additional inch in rim diameter (18 inch to 19 inch) fitted to a 250cc machine for example, the size would change from a 110/100-18 to a 110/90-19. The resulting low profile 19 inch tires with shorter sidewalls have provided improved stability performance, while retaining the same outside tire diameter.
  
• Building on the success of the 19 inch rear tire, Dunlop in the mid 1990’s became the first tire manufacturer to develop wider, lower profile motocross rear tires. The technology in the 110/80-19 & 120/80-19 creates a larger footprint for enhance traction and bump absorption. In the late 1990’s, Dunlop introduced a wider 90/100-21 front tire to compliment the rears. In each case, these wider, low-profile tires fit on existing standard-size rim widths, eliminating the need to replace rims.
  

One of the most frequently asked technical questions we get at VP involves the difference between Motor, Research and R+M/2 Octane Numbers. The next most frequently asked question is why some fuel companies represent their fuels with Motor Octane Numbers, while other companies use Research or R+M/2 Octane Numbers.

Realize first that octane is a measurement of a fuel’s ability to resist detonation—nothing more.  The two types of machines used for testing octane—a Motor Octane machine and a Research Octane machine—were designed in the 1930s.  They were designed to test for octane numbers from the 0-100 range, therefore, any number above 100 is an extrapolation.

Both of these machines are dinosaurs and are not adequate for today’s high tech fuels or engines, but they’re the only means available for testing fuels. These machines are one-cylinder engines with an adjustable head that can move up or down to increase or lower the compression ratio while the engine is running. The Motor and Research machines are the same in this respect, but they differ in several other characteristics.

The following is a comparison of the two machines used for testing octane numbers:

Motor

RPM

INTAKE TEMP

TIMING

Octane Machine

 900

300 DEGREES F

VARIABLE BASIC

 Research Octane Machine

600

120 DEGREES F

FIXED AT 13

DEGREES
(DOES NOT CHANGE)
SETTING 26 DEGREES

As you can see, the Motor Octane machine runs at a higher RPM, higher temperature and more timing. This machine puts more stress on the fuel than a Research machine and more accurately simulates a racing engine. VP Racing Fuels always includes Motor Octane Numbers when promoting its fuels because our fuels are used exclusively for racing applications.

The Research Octane machine will always produce a higher number for the obvious reason that it does not put the same amount of stress on the fuel. This number is used by some fuel companies to trick the racer into thinking the fuel is rated higher, i.e., higher quality, than it really is. The “R+M/2” Octane Number is the average of the Research and Motor Octane numbers for a fuel and is the number displayed with yellow labels on retail level gas pumps.

When comparing fuels for racing purposes make sure to compare Motor Octane Numbers because these are the ones that count in your racing application. Focusing on the MON of each fuel will help ensure you’re comparing apples to apples with regard to octane.

But bear in mind, a fuel’s ability to prevent detonation is a function of more than just octane.  For example, VP’s fuels—oxygenated or nonoxygenated—vaporize much better than competitive fuels with comparable octane ratings.  This means VP fuels cool the intake charge, burn faster and yield more efficient combustion. As a result, the “effective” octane rating of VP’s fuels is even higher than the rating generated by the octane test.  As a result, VP fuels will prevent detonation more effectively than competitive fuels with comparable MONs.

Too often, racers focus only on octane when evaluating the quality of a fuel.  Octane is certainly important, but it’s just one of several key fuel properties that should be considered when evaluating and selecting a fuel.  It’s entirely possible to generate more horsepower with a lower octane fuel if it’s designed properly with respect to its other key properties.  It’s also possible for two fuels to have the same octane rating, but perform very differently due to their other key properties.

1.    OCTANE: Octane is simply a rating of a fuel’s ability to resist detonation and/or preignition. It is not so much an indication of a fuel’s ability to make power, but rather a fuel’s ability to make power safely, i.e., without blowing your engine.  Octane is rated in Research Octane Numbers (RON), Motor Octane Numbers (MON) and Pump Octane Numbers (R+M/2).  A Pump Octane Number is the number you see on the yellow decal at gas stations, representing the average of the fuel’s RON and MON. (See below for a more detailed explanation of how octane numbers are derived and what they represent.)

VP relies on MON numbers because the MON test more accurately simulates racing conditions.  Don’t be fooled by high RON or R+M/2 numbers. Many companies use these simply because they look higher and are easier to come by because of the test methods.  Also bear in mind that the ability of fuel to resist detonation is more than just a function of octane.

2.    BURNING SPEED: This is the speed at which fuel releases its energy and is partially  a function of a fuel’s vaporization qualities. At high RPMs, there is very little time (real time – not crank rotation) for the fuel to release its energy. Peak cylinder pressure should occur around 20˚ ATDC. If the fuel is still burning after this, it’s not contributing to peak cylinder pressure, which is what the rear wheels see. Because VP’s fuels are designed with a particular focus on vaporization characteristics, most of VP’s fuels—oxygenated or nonoxygenated—vaporize much better than comparable competitive fuels.  This means it cools the intake charge, burns faster and yields more efficient combustion. As a result, the “effective” octane rating of VP’s fuels is even higher than the octane test indicates, and they will prevent detonation better than competitive fuels with similar MONs.

3.     ENERGY VALUE: Energy value is an expression of the potential energy in fuel. The energy value is measured in BTUs per pound, not per gallon. The difference is important as the air/fuel ratio is in weight, not volume.  Generally speaking, VP’s fuels measure high in BTUs per pound and thus, have a higher energy value. This higher energy value will have a positive impact on horsepower at any compression ratio or engine speed.

4.    COOLING EFFECT: The cooling effect of fuel is related to the heat of vaporization. The higher a fuel’s heat of vaporization, the better its ability to cool the intake mixture. The superior vaporization characteristics of VP’s fuels make cooling effect one of their key advantages. A better cooling effect can generate some horsepower gains in 4-stroke engines and even bigger gains in 2-stroke engines.  VP’s superior cooling effect can also ensure circle track racers maintain power in the longest races and harshest conditions.  In virtually any application, the cooling effect of VP’s fuels will help extend engine life.

Understanding these key properties of fuel will better equip you to evaluate fuels for your application.  By clicking on your application to the right,
you’ll find a list of VP fuels designed with you in mind, along with the fuels’ relevant characteristics.

Before making a final fuel selection, we encourage you to consult with your VP regional distribution center or VP’s Technical Support Staff.
Be prepared to answer the following questions:

•    Is your engine naturally aspirated, turbocharged, blown or using nitrous oxide?
•    What is the compression ratio (CR) of your engine?
•    Does your engine have O2 sensors or CATS?
•    In what series or sanctioning body will you be racing?
•    What are their fuel rules, e.g,. are any fuels illegal or do they allow oxygenated fuels?
•    In which class will you be racing?

You can be confident that once we understand your application, we’ll find the fuel that will make the most power for your engine!

Yes you can over octane an engine.  Generally you will get sluggish throttle response.  Also you may get fouled plugs and deposits in the exhaust ports and headers.  When an engine is trying to burn a fuel that has too much octane, the burn rate is incorrect and all of the fuel won’t be used up.  This excess usually gets left as a deposit or gets pushed out the exhaust.  It is important to match your engine’s needs with the correct fuel.

1. Soak the filter Put three liters of tap water, as hot as possible in the special purpose designed cleaning tub. Add 100ml of Bio Dirt Remover to the water (One filter needs 100ml of Bio Dirt Remover)Fully immerse the dirty filter (wear protective or disposable gloves and be careful not to burn your hands), and let it soak for ten to fifteen minutes.
2. Squeeze the filter Squeeze the filter several times (do not wring!), repeat this procedure until all the dirt has disapeared.
3. Wash the filter Wash the filter with clean, cold tap water until all the soap residue has been removed. Leave the filter out to dry, under a piece of cloth. Once the filter is dry, it is ready to be pre-oiled again. TIP: Oiling the filter without allowing it to dry sufficiently will trap some of the moisture.
4. Oil the filter Soak filter in BIO Liquid Power Filter Oil, making sure to saturate the entire filter, coating the filter uniformly. Be sure to apply oil to the inside and outside of the filter. TIP: Don't oil your air filter right before riding. Preoil the filter at least 24 hrs before riding to allow the oil to evenly penetrate the pores and allow the thinning agent to evaporate. A recently oiled filter will cause rich conditions.
5. Squeeze excess Squeeze excess oil out of the filter so that a light coat of oil remains. Continue to massage until the filter is evenly coated. 
6. Dry the filter Leave the filter out to dry in a well-ventilated area, preferably outside in the open air under a piece of cloth. After approximately 2 hours, the filter is ready to be used. Store pre-oiled filters in the resealable Twin Air bag (or an airtight plastic bag) and in a dark spot.
7. Install the filter Install the cage into the filter and install filter into airbox. Before installing check carburetor boot for dirt.