Top Gun DR650 Tachometer

Well, as I look back at the article index I can see that I haven’t been keeping up with Elden.
But, we’ve had a lot going on here, several products being put out or in the works,
purchasing and studying the new 2008 KLR, etc. I hope everyone is enjoying the riding
season, now in full swing. Here are a few questions we’ve either been asked, or have seen
posted on the Internet:

Q. Why would I buy a Top Gun DR650 tachometer when I can get a full-featured
Trail Tech computer for just a little more?

A. Honestly, if you can get the Trail Tech computer for “just a little more” and you want the
extra features, I say “buy it.” In my house, the extra $40 or so needed to buy a basic Trail
Tech doesn’t necessarily qualify as “just a little more,” but that’s another story! Here’s a
little background on how we developed our particular tachometer.

I initially wanted to find a tachometer for evaluating gearing changes and frankly, because I
was curious to see how that little DR motor ran. My search eventually led me to Trail Tech,
and I was seriously considering buying one of their computers. However, the model I was
looking at was over $100 and although it had some cool features, I wasn’t sure that I
needed them. About this same time, Elden and I ran our KLR vs. DR temperature
comparison. That test made me realize that I didn’t need to worry about the DR’s ability to

stay cool. I also realized that I didn’t need a computer to tell me the outside temperature – I
generally check the weather before I leave the garage. And although I like the capability to
change the computer’s speedo settings to account for different size tires, I didn’t like the
idea enough to want to replace my stock speedometer or play around with setting up the
magnetic pick-up. That left me right where I started: trying to find a plain old tachometer.
Long story short, I found one that is simple, rugged, reliable, and self-powered. Elden
initially looked at it with some skepticism, but eventually grew to like it so much that we
decided to make a proper bracket for it, and we had our Tach Kit.

We never intended this tachometer to compete with a full-feature computer. I think the Trail
Tech computers are very nice and would certainly consider one under other circumstances.
We wanted to have a nice little tach that came complete with everything you needed for
installation. If you’ve been looking for a way to evaluate your gearing selections or miss
having a tachometer to see how your engine is performing, we think you’ll be happy with
ours.

Here’s an interesting picture sent to us from Dave from “Down Under.” Dave purchased two
of our tachs, installing one on his DR650 an the other on his Yamaha TW200. Never
underestimate the resourcefulness of an Aussie!

World's Only TW200 equipped with  a Top Gun tachometer!

World’s Only TW200 equipped with
a Top Gun tachometer!

Q. What gearing do you recommend for freeway/higher speed driving? 

 

A. One thing we see frequently is people over-
gearing their motorcycle in a quest for more
highway speed. The KLR650 comes stock with
15/43 gearing; the DR650 with 15/42. Although
I’m sure there are smaller riders who could get
away with higher gearing, I would say as a rule of thumb, DON’T use a 16T counter sprocket on either of these motorcycles. Even with
stock gearing, these bikes could easily be over-geared for a larger rider, or an average
rider with a lot of gear. I’m 6’2”, 185lbs, with a tall sitting height. I find that 15/45 gearing (I
actually use the equivalent gearing of 14/42) is great for me around the SoCal mountains,
and even for the occasional higher speed freeway run.

I conducted a little experiment with this question in mind. Until just recently, my daily
commute was 20 miles one-way. I normally cruised around 4500-4700 RPM, which gave me
a speed of about 68-70 mph. I averaged 50.0 mpg over 2,946 miles over four months. I
switched gearing back to stock and ran the same RPM range, which gave me speeds
between 72-75 mph. My mileage over 753 miles during the next several weeks dropped to
an average of 45.6 mpg. And remember, this was over the same route, same bike, with the
same rider and gear as before. The only variable was speed.

Each increase in speed has a correspondingly larger effect on drag. Using some
representative numbers for frontal area and coefficient of drag (a unit-less measure of how
“slippery” your bike is), it would take 11.2 hp just to overcome the aerodynamic drag force at
65 mph. An increase of just 10 mph to 75 requires 17.2 hp. That’s a 45% increase in
horsepower just to give you that extra 10 mph! Increase your speed to 85 mph, and you’d
need 25 hp to overcome drag. Get the idea? On a single-cylinder motorcycle, you don’t
have a lot of extra horsepower to give away, and at today’s gas prices, you may not have
money to give away either. More importantly, your engine is now working harder than at the
same RPM with lower gearing.

Bottom line: gear your bike appropriately for your size, load, and your riding environment.
And be honest with yourself. If you really have to ride on the freeway at 80+ mph, you
probably should find the proper tool for the job and buy a different motorcycle.

Q. Mike called us wondering: “What bike would you recommend for a ride from
California to Argentina?”

A. Elden Carl has helped several well-known long distance riders prep their bikes, including
world travelers Mariola Cichon, Richard Kickbush (consultant only – no hands on), and Greg
Frazier (all three on KLR’s); Avi Fishali and his 3 ex-Israeli Army buddies who traveled from
San Diego to the tip of Argentina (all on KLR’s); Bruce Redding, who has made numerous
trips across North, Central, and South America (KLR); Dave Waters, Iron Butt KLR rider and
soon to be preparing for a “Three Flags Run”; and Wes Mudge, currently on a Mexico to
Canada tour on as much dirt as possible (DR650). Elden had a long and enjoyable talk with
Mike about some of the various alternatives: KLR650 (2008 and previous models), DR650,
DL650, BMW F650 etc. Although the DL is a fine motorcycle, maybe the best street
motorcycle/dollar on the market, Suzuki did not design this bike to be used for anything
besides sticky pavement and the occasional well-groomed dirt road. Likewise with the F650,
though the Dakar version is probably more at home in the dirt than the Vstrom. However, it
may be tough to find high octane fuel to feed the higher compression Beemer as you get
further away from civilization. The DR650 is one of our favorite bikes, but its compact size
makes it tough to find enough places to put your gear for a long trip. Which leaves us with
the venerable KLR650. We wouldn’t dare head south on our 2008, but we still believe that a
properly set-up and maintained (pre-2008) KLR650 can take you anywhere you want to go;
and do so more reliably and with better off-road performance and fuel economy than any of
the 1000cc “adventure bikes.” We hope to talk more with Mike in the future and look forward
to hearing about his ride.