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What to Know When Choosing a Fork Oil

Fork Oil – Which do I use?

We sell a good amount of fork oil in Sioux Falls thanks to some great motorcycle shops who know how to maintain the various units out there. But if you have a shop manual, the right tools and some patience give it a try!  Some units are very simple, quick and easy.

A fork oil’s number-one task is to deliver consistency. Consistent dampening despite temperature changes. Consistent rebounds despite different terrain. Consistent performance so you can ride or drive confidently.

Consistency.

What fluid would provide the best shock consistency?

Water.

Yes, water. But you don’t want to use it in your shocks for reasons you can probably guess, but we’ll get to that in a bit.

What shocks do

The shocks on your dirt bike, race car, ATV or other vehicle absorb abnormalities in the terrain and help stabilize the ride. They also absorb impact when landing a jump, taking some of the beating off the vehicle and your body. And they “load up” with energy when approaching a jump, helping you fly over whatever’s in your way.

The shock uses fluid to control dampening and rebound.

Say you’re riding your dirt bike and land a jump. The force depresses a piston inside the shock that pushes fork oil through calibrated valves. The fluid’s rate of flow through the valves influences the amount of dampening and rebound.

A thin fluid flows faster and results in quicker, springier shock feel. In contrast, a thick fluid flows more slowly and results in slower rebound and stiffer shock feel.

Fork oil viscosity matters

The fluid’s viscosity (often thought of as its thickness) influences how fast or slow the oil flows through the shock valves. If you prefer quick rebounds, use a lighter fluid. If you like slower rebounds, use a heavier fluid.

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Easy, right?

Sure, if the viscosity of the shock oil never changes.

However, cold ambient temperatures increase the oil’s viscosity, resulting in slower rebounds. Then, after you’ve made a few laps and the vehicle’s heated up, the fork oil thins as it warms. That’s because fluids become thinner when they warm up. Think of molasses or honey. The warmer oil flows faster through the shock valves, leading to inconsistent shock feel.

H2O, no

That’s why water theoretically would provide the most consistent shock feel. Its viscosity doesn’t change between 33ºF (0ºC) and 211ºF (100ºC).

On a cold morning, after a long ride or on a blazing-hot day, water maintains the same viscosity provided it doesn’t freeze or boil. When was the last time you had a thin or thick glass of water? Hence, it would flow at the same rate through the shock valves, resulting in consistent feel.

Much more than flow, though

But the fork oil must do more than influence rebound and ride feel. It also must protect against wear and corrosion, two tasks at which water is notoriously bad.

The shock oil has to protect the shock tubes, seals and valves from wear as they constantly rub together. Minus good wear protection, the shock would tear itself apart in short order. Plus, the oil must form a layer on parts to prevent formation of corrosion. If corrosion starts, it won’t stop, spreading and depositing flakes of contaminant in the oil that act like sandpaper and scour metal parts until they’re worn out.

Look for a high-VI fork oil

Instead, look for a fork oil with a high viscosity index (VI). A higher VI indicates better resistance to viscosity changes throughout broad temperature swings. That translates into consistent shock performance and feel despite the ambient and operating conditions. And a consistent ride equals a more effective rider.

Points to consider when looking for fork oil

1) No standard viscosity

Your engine manufacturer recommends a specific viscosity of motor oil for best protection and performance. In the world of shocks, there are no universal viscosity requirements or recommendations. Each shock oil manufacturer is free to formulate its oils to whatever viscosity it deems appropriate. That means one brand’s “light” fluid could behave like another brand’s “medium” fluid, and so on.

2) Once you find a shock oil you like, stick with it

For the reasons listed above, avoid switching between fluids if you can. Once you have the proper suspension set-up for your body weight and riding style, stick with it. The shock oil is one of the biggest variables in your suspension tune, and messing with it can throw off suspension feel and your riding confidence.

3) Look at viscosity at 40ºC

If you decide to switch shock oil, compare the viscosity of the fluid you’re currently using at 40ºC to the same data for the new fluid. The closer the results, the more similar the oils will perform. Reputable manufacturers publish product data bulletins for their shock oils and post them online. If you can’t find a data sheet for the oil you’re considering, think twice before using it.

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AMSOIL-Sponsored Chase Sexton Takes Supercross Crown

AMSOIL-Sponsored Chase Sexton Takes Supercross Crown

As I plopped down on the sofa with my second cup of coffee Sunday morning, I tuned the DVR to watch the Supercross finals from Vegas (#centraltimezoneprobs). I knew two things from watching heats and LCQs the night before:

1. Those whoops were pretty gnarly.

2. With temperatures steadily approaching triple digits during the day, the track was drying pretty fast, making it super slick.

But, I also knew that GEICO/AMSOIL/Honda’s Chase Sexton just had to finish in sixth place or better to secure his first 250 Supercross championship.

Championship within reach

Even if Justin Cooper (who sat 10 points behind Sexton) were to win the East/West Shootout, Sexton would secure his first championship by finishing at least sixth in the main event. Mimicking the patient, controlled riding style he’d displayed all season, the GEICO/AMSOIL/Honda rider sailed through in the top five, ultimately crossing the finish line in fourth place and securing a 250SX East Championship.

Initially slated to run in the East Coast series, Sexton switched to the West a week before the start of the season after an injury to Christian Craig. After breaking his collarbone while riding his mountain bike, the 2018 Rookie of the Year switched again back to the East. Cameron McAdoo stepped in, filling his vacant spot on the West.

Patience pays off

Consistently riding in control throughout the season, Sexton landed his first career win in East Rutherford, N.J. After an injury took front-runner Austin Forkner out of the title running in that same round, Sexton moved into first place with just the finale left to go.

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Qualifying second Sexton headed to the final in Vegas knowing what he had to do. In addition to Sexton’s championship, GEICO/AMSOIL/Honda riders RJ Hampshire and Cameron McAdoo capped the team’s night with second- and third-place finishes, respectively.

“It feels super good; it hasn’t really sunk in yet, being 19 years old and winning my first championship is unbelievable.”

Chase Sexton

“It was the longest 15 minutes plus one [lap] I’ve ever done; track was gnarly. Yeah, it was a super-sketchy track, and the whoops were gnarly. [I] had some moments with my teammate, and there were some hay bales knocked out on the track. It was really hard to decide if it was a good move or bad move, but it couldn’t have worked out better.”

Riding high from the championship fumes, the attention now turns to the outdoors with the opening round of Pro Motocross from Hangtown in Sacramento, Calif., just more than a week away.

As always, be sure to tune into our FacebookInstagram and Twitter to see how #TeamAMSOIL is doing and where we are off to next.

We’ll see you at the races!

Take a Ride Around the Milestone MX Track

Take a Ride Around the Milestone MX Track

Hunter and Jett Lawrence have had quite the journey to American motocross.

After following the path of other successful Aussie riders like Chad Reed and Andrew McFarlane, they traveled to Europe to transition their careers to a larger scale, eventually landing on the AMSOIL/Honda and GEICO/Honda teams for the 2019 season. With his Supercross season delayed by a broken collarbone, Hunter Lawrence decided to get some laps in at the AMSOIL West Coast Open Swap Moto Race Series. With little brother Jett tagging along, the two went bar-to-bar this past Sunday on the main track. Meanwhile, over on the amateur track, the Pee Wees were ripping it up, with an all-out battle to the finish line.

Swap Moto Race Series

AMSOIL is the presenting sponsor of the Swap Moto Race Series. Formerly knowns as Transworld Motocross Race Series, the Swap Moto Race Series runs a unique two-track format, which shortens the race day for riders in its 60-plus classes. The series also boasts free transponders and low entry fees. Consisting of three separate “mini series” (West Coast Open, Terra Firma, Fall Classic), the entire series runs from January through December. Racers travel to some of the most notable tracks in Southern California. Check out a series schedule here.

Check out last weekend’s track setup at Milestone MX Park below.

This past weekend we took a trip out to California to check out the third round of the AMSOIL West Coast Open at Milestone MX. We caught up with the Lawrence brothers, checked out some racing on both tracks and learned a little more about what the series has to offer. Head on over to our Instagram to check out our highlights from our visit.

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As a part of our sponsorship with the series, AMSOIL will be offering contingency at the end of each of the three mini series. Gift certificates will be awarded for eligible classes for first through fifth place in the following amounts:

1st $200.00 and a Preferred Racer Membership
2nd $150.00 and a Preferred Racer Membership
3rd $75.00 and a Preferred Racer Membership
4th $50.00 and a Preferred Racer Membership
5th $50.00 and a Preferred Racer Membership

At the end of the day after about 40 classes had finished their motos, the Lawrence brothers went one/two (Hunter, Jett) in the 250F class. The brothers had some competition in the Pro Open (125-450) class, with Hunter finishing in second and Jett in third.

Be sure to tune into our FacebookInstagram and Twitter to see where we’re off to next.

We’ll see you at the races!