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Cobra Friction Drive Tech Video

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TechUpdateThere is no question that Cobra’s patented CFD (or ‘slipper’ as most call it) plays are large role in driveline durability. For years prior to its introduction, the sights broken transmission gears or a snapped chains were relatively commonplace at the race track. The device’s operating principal is relatively simple: The CFD adds some ‘give’ to the driveline system. Unlike other types of motorcycle transmissions, when a centrifugal clutch (used on all 50cc motocrossers) is locked up, the entire powertrain…everything from the rear wheel to the piston…is also locked. Now imagine landing off a big jump with the throttle pinned. The engine is spinning at close to 15,000rpm, and then SLAM, the rear wheel comes to almost a dead stop as it hits the ground. With very little give in the system, this results in brutal wear and tear on many components such as the crankshaft, clutch basket, clutch shoes, transmission gears, transmission bearings, chain, sprockets, and rear wheel.

So how does the CFD work? It’s very simple, actually. The primary gear, instead of being one solid part, has been replaced by a clutch that is set to disengage at a pre-determined torque level. This break-away torque is several times the maximum engine torque (so it doesn’t slip when the engine is driving it), however, when it receives a high load in the other direction it spins providing a cushioning effect on many expensive engine and driveline components.

So what does this mean on and off the racetrack?

  • More time riding and less time doing maintenance!
  • Durability improvements in all driveline components.
  • Longer clutch shoe life.
  • Reduced weight and friction in the engine’s final drive and more power to the ground.
  • The freedom to aggressively throttle away from heavy landings without having to worry about things breaking.
  • Overall reduced cost of ownership!
  • and Last but not Least…Improved rear suspension performance because the driveline can now absorb some of the impacts from hitting square edged obstacles rather than kicking the rear wheel.

So, all that’s left is to make sure that owners can properly maintain their CFD, and that’s why we created this video. Pay particular attention to this practice when you have a new bike or install a refresh kit as it takes a few rides for the system to take a set.

Race Gas…Is it worth the money?

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Yes and No…How’s that answer for ya?

We first of all need to separate out the discussion on race gas between 50cc auto engines and 65cc multi-speed engines. Both behave very differently with respect to fuel variations, and since the 50cc auto engine is the more finicky of the two, most of this conversation will focus on it.

Here is the issue: The vast majority of the time, putting race gas in your 50cc engine will harm rather than help your situation when using it instead of a good 93 octane pump gas. Note the emphasis on the word good…Many pump gasses are anything but good. Nearly all contain components other than gasoline, and much of the time this is due to federal and local laws mandating ‘clean’ fuels for various times of the year (i.e. summer gas vs. winter gas). So…Filling up in June vs. filling up in November – even from the same gas station – can result in a very different product in your gas can. As a result, this can lead to variations in performance, jetting requirements, and tolerance to engine damaging detonation.

Furthermore, there have been several investigative journalism pieces lately on the quality of pump gas, and the results were downright scary. Dateline NBC, for example, found pump gas as low as 75 octane! The show tested 85 different samples of ‘name brand’ premium gasoline purchased in California, and out of that group there were 11 that tested below the octane posted on the pump.

Car and Driver magazine followed up by reporting that in Michigan, the Bureau of Weights and Measures failed 217 of 2816 samples of ‘high test’ pump gas because of low octane. It also has been reported that 15% of the gasoline in New York State is substandard.

Bottom line: what you get from the pump varies widely in quality and in chemistry. You are rolling the dice when purchasing race fuel from a corner gas station.

What to do?

Maybe a better question is what not to do…

1) Don’t purchase fuel on the road if you can help it. Chances are the local laws (i.e. how much ethanol must be mixed with gasoline) are different that what you are used to, and as shown above, the quality of fuel can be a crapshoot.

2) Don’t bother with ‘octane enhancers’. None of our testing has ever shown these additives to do anything.

3) Don’t blindly purchase race fuel and think your bike will run better…Many times (especially a 50cc auto), it won’t.

4) Don’t be too aggressive in running advanced spark timing (>0.040” on a Cobra 50cc auto). This will only make your engine more sensitive to detonation, and the combination of advanced spark timing and poor quality gasoline can melt down an engine quickly. For more information on how to set spark timing, see your manual.

Some tips:

1) For 65cc and larger bikes, purchase race fuel and use at least a 50:50 blend with high test pump gas from a local, trusted fuel retailer. VP U4-2 is a good example of a fuel that keeps engines free of detonation and improves overall power output.

2) For 50cc bikes, we still recommend 93 octane gasoline without any ethanol added. This is not easy to find these days, however, there are some tools to help you navigate which retailers to use and which ones to stay away from. First of all, it needs to be noted that not all states mandate Ethanol labeling at the pump. For a comprehensive list of states check here. Secondly, if you really want to know you are getting pure gasoline, then you need to purchase a tester. They are not expensive (about $30), and they can come in handy if you are on the road and need to find fuel. Here’s an example of a fuel tester you can purchase online.

3) Be prepared to chase jetting with race fuel. The vast majority of race fuels are more sensitive to changes in atmospheric conditions than pump gas. This means that the jetting that worked in morning practice may be way off by the time your afternoon moto rolls around.

4) Don’t believe the hype. Unless you see hard data that a fuel or additive works, don’t trust it. Moreover, NEVER try a fuel at a big race for the first time (yea, I know…You need every advantage you can get). Unless you have tested, raced, and tested some more, stick with what you know.

Lessons for the day: 1) be careful…Variations in fuel quality and chemistry are big. 2) Know what you are putting in your tank, 3) Don’t jump at magic bullet solutions for race gas or additives…The vast majority of the time you will go backward and in the worst case do a lot of expensive damage to your engine.

See you at the races…

Sean @ Cobra

Handy Dandy Chart

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Cobra_Gear_ChartWe put this gearing chart together for the 2005 service manuals, however, it’s so handy we thought we’d post it right away. Print it out and stick it in your tool box or on the wall of your trailer!

(note: you must click on the image to open a full size version)

Five Tips to a Better Race Season

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After spending some time at the races this spring, we saw a few common mistakes in the pits that reminded us that there are a lot of new folks in the sport, and passing some advise on to our customers will hopefully help you avoid some frustration and possibly even lessen your out-of-pocket racing costs…So here it goes: Five tips for this week:

1) Careful with those brakes! Be very careful how you adjust the rear brake on the 2004 King. Whenever you change the pedal height, you must also adjust the master cylinder plunger height. We’ve seen a lot of folks lower the pedal height and not change the plunger depth. This results in a dragging rear brake which will definitely reduce pad life and possibly reduce clutch life as well. Make sure that the rear brake also has some free play just in case your little racer has his or her foot on the brake pedal while riding.

2) No Stomping Allowed. It’s okay to ‘clean out’ and warm up the engine at the starting line, however, it’s not a good idea to rev the engine to 14,000 RPM and then stomp on the rear brake. Believe it or not, this creates a lot of stress on the internal engine, transmission, and clutch components. Stop the rear wheel slowly, and your engine (and pocket book) will be a lot better off…

3) The blippers are back! Believe it or not, blipping the throttle on and off through the pits is actually harder on the bike than running it hard on the race track. Blipping never allows the clutch to fully hook up…it just sits there slipping and creating heat. That extra heat is not good for your engine seals, bearings, or electronics. Keep blipping to a minimum, and your engine will last a lot longer.

4) Leave the race gas for the family dragster. The vast majority of race gas blends actually reduce the performance of a 50cc race engine. High octane, by design, slows down the burn rate of the fuel. This is important in slow turning large bore engines where the end gasses have a lot of ‘bake time’ and detonation occurs easily. In a small bore 50cc engine that makes peak power around 12,000 RPM, a slower burning mixture is neither needed nor does it increase power. Save a few bucks and go with 93 Octane pump gas (Mixed with Cobra Venom 50cc blend, of course).

5) And, speaking of oil….There is absolutely no reason not to run a 32:1 mixture. There is no discernable performance or jetting advantage by going cheap on oil. In fact having a little extra oil on metal surfaces can actually increase performance by reducing friction. With as hard as these little high-revvers work, the added oil is good insurance against catastrophic engine failure as well.

See you at the races!