Copperhead ECU for 700 King Quad

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By: Tim Criddle, Calgary, Alberta

Review of Copperhead Engine Control Unit (ECU) for Suzuki King Quad 700 from Velocity Devices Inc of Calgary, Alberta, Canada.

As an owner of a 2006 Suzuki King Quad 700 with a K & N air filter, Carlisle ACT X/LR 6 ply radial all conditions tires, quad boxes front and rear, front winch, and rear Highlifter springs, there are certain features of my quad that I think are second to none.

That’s pride of ownership coming through I’m sure. Having said that, there are certain things about the quad that I would like to see changed, or at least things that I would like to have the ability to change or modify (mods, a word synonymous with owning quads and other power sport ‘toys’).

Although the engine, single cylinder 695 cc fuel injected unit is quite powerful, and the top end speed of this quad is simple too darn fast for sane people to want to ride at on 4 or 5 psi tires, there is an annoying “lag” from a standstill, a low end “detune” engineered by Suzuki intentionally.

This is one of the safety features that has been engineered into this quad to essentially harness and control the huge amount of power potential that the engine has. Why would they do this? To keep the front end down, to prevent the front end from coming up and over when hill climbing, presumably, if someone, especially an inexperienced rider, were to use too much throttle in that situation.

I don’t blame Suzuki for engineering safety features into their products, but in this case, they seem to have gone to quite an extreme in limiting the power of the engine that they chose to utilize in their big bore machine.

So much so that there are other annoying safety features that, again, may benefit a novice rider, but are not completely necessary with experienced riders. These other safety features include an engine rev limiter while operating in reverse. There is a manual override button the operator must depress to have access to more engine power when in reverse, but only for a short bit of time before the rev limiter takes over.

When operating in reverse, it is a pathetic and sorry state of a machine with the rev limiter, as it barks and sputters like a sick mule. The same thing occurs when operating with the front differential lock engaged; there is once again an engine rev limiter that must be manually overrode to have access to greater engine power.

When you are in a situation that requires the front diff lock to be engaged, quite often that would mean you are in a technically challenging spot and should focus more on maneuvering the quad without having to think about depressing the override button.

Another annoying side effect of the engine detune is the apparent retarded firing, which causes the engine to fire with the piston somewhere midway down the cylinder. This causes a lack of power, intentionally, as you won’t get full stroke on the piston.

As I understand it, you also have all of that heat from the combustion being shot right into the cylinder walls, causing serious engine heating. With my stock ECU, my engine gives off a lot of heat and the fan cuts on frequently.

The Copperhead to the rescue

In 2006, I started reading about the development of an aftermarket ECU to replace the stock Suzuki one. Lyle at Velocity Devices Inc ( owns an Artic Cat 700 with the same Suzuki 700 engine, and the same detuned ECU. Since he has taken on the challenge of developing, successfully, replacement Coppperhead ECU modules for the Kawasaki Brute Force and the Yamaha Grizzly, he threw his R and D efforts at a replacement for the King Quad and AC 700s.

Lyle’s approach to this project has been to engage owners of the King Quads in the discussions and on-going development of the Copperhead, which is a very unique approach. Most R and D projects take place in very secretive and controlled environments. King Quad owners lived and breathed every one of Lyle’s hiccups and set backs and discoveries and victories in a very public on-line forum. Faithfully, Lyle would update his legions of followers on the status of the development.

Since I own a King Quad, live in Calgary where Lyle is located, and am extremely interested and curious in the development of this major performance enhancer, I contacted Lyle and offered the use of my King Quad to him for testing. He took me up on it, and had it to his shop three times for tuning, testing, and horse power verification on his dyno.

I became one of his Beta Testers as well, putting the Copperhead to the test on the trails in real world environments. For approximately two months, I, amongst others, worked with Lyle in the final stages of the development of the Copperhead for the King Quad and AC700.

The Copperhead has now been released to the masses, with a huge waitlist gobbling up the first 250 units in mere days. Try and tell me people did not notice the annoying low end lag, eh?

From my experience on the seat of my King Quad, here are the most memorable and key points:

No Low End Lag. It’s gone. I never knew how responsive the engine could be until the lag was eliminated. As I understand it, the Copperhead has added roughly 21% more horsepower to the King Quad’s power across all throttle ranges, and up to 40% in the mid ranges. In fact, if you are so inclined, put the quad in low range 2 wheel drive, and punch the throttle. You had better be careful, and be wearing a helmet and suitable riding gear, because the front end comes up and the unit will wheelie like a champ (wheelies, for some crazy reason, are a significant test requirement and measurement of the Copperhead’s performance, a badge of honor, if you will.).

Now I don’t mean standing on the back rack and pulling up on the handlebars with ape arms either…pure torque to the ground will pick up the front end. I have a front box on mine, full of tools too. In high range, you can wheelie the unit with a gentle tug back on the handlebars.

The other anecdotal measurement of the Copperhead performance is off-the-line drag race speed. I am not into drag racing my quad nor am I overly interested in it’s top end speed, but I can assure the masses who do care, the off-the-line response is simply outstanding. I’ll let others find out what the new and improved top end speed is. However, while wheelies and drag racing are not important to me or my riding style, having crisp and immediate throttle response is important.

Why would you want the low end lag gone? Let me put it to you this way. To climb over an obstacle such as a log or up out of a rut for instance, with the low end lag, you end up using more throttle than you should have to in order to reach the power to get over the log.

Once clear of the log, your quad is now revved up with too much power and you have to back off right away. To use a knife analogy, it’s safer to cut with a sharp knife than a dull one. Why? Because it takes less effort and force to cut with a sharp knife, whereas it takes more effort and force to cut with a dull knife, potentially causing someone to lose control and cause injury to them or others.

If you had the required amount of power and throttle response, you could clear the log without actually using too much throttle, and not be in a situation of having too much power once the engine caught up.

The rev limiters are gone both when operating in reverse, and when operating with the front differential engaged. You now have full engine power to back up out of a mud hole, or to power straight through tough, rugged, muddy, technical situations. It’s that simple.

The engine runs cooler. One day while still beta testing, I ran the King Quad in the morning with the Copperhead installed in lots of stop, start, and low speed operations, when typically the engine heats the most. In the afternoon, I put the stock ECU back in. It was not until mid afternoon that I realized that my fan had barely turned on all morning in the direct sunlight and heat of the day, while in the overcast and cooler air of the afternoon (the weather changed and it got cooler) it was running almost constantly and the heat emanating from the engine compartment of my quad was simply radiating. As I understand it, the Copperhead advances the timing, giving the engine more power, and causing less heat being disbursed out through the cylinder walls.

What about inexperienced or novice riders? No problem. The Copperhead comes with two changeable settings with a small toggle switch. One setting is for pure performance with full engine power and rev limiters eliminated. Another setting can be for stock settings, with safety features enabled. However, the Copperhead can be ordered for pure performance with one setting for 87 octane fuel and a the second setting for 91 octane fuel.

What about firmware changes or programming/fine tuning? As an option, customers can purchase the USB interface cable and USB Memory Interface as well. This enables you to download firmware or fine tune the firmware settings and download them into the Copperhead from a laptop computer. VDI have a very good reputation for after sale support, and also have a good support section on their website complete with a good Copperhead whitepaper, well worth the read.

What about tuning for aftermarket pipes? Lyle has indicated that in short order, he will have maps for use with aftermarket higher flow exhaust pipes. Watch the support section on VDI’s website for updates.

How does the Copperhead compare to already available PC fuel controllers? Read the comparison white paper here.

What is the price? At the time of writing, VDI are selling the Copperhead ECU for the King Quad for $500.00 Canadian plus taxes and shipping. The USB cable is $10.00 and the USB Memory Interface for programming is $50.00, Canadian prices plus shipping and taxes. They are available on their e-commerce web site, and in short order will be available from select retailers. Contact VDI to find a dealer near you.

Is it worth it? Above all else, that is the most important question. It really boils down to what type of rider are you? What type of conditions do you ride? What demands do you place on your ATV? If you are experienced and can handle the big bore quads, ride in situations where low end lags and rev limiters will simply frustrate you because your quad will not be performing at it’s peak, then for sure, the investment in the Copperhead is for you. Isn’t that the name of the game with power sport toys to begin with? I mean, what fun would these things be if we didn’t have mods to add to them to enhance performance, appearance, functionality, and the overall FUN factor?

For me, my riding style and performance demands of my quad, it’s worth it.

For more information, please visit Velocity Devices Inc at

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