One of the things that was lacking on my rescued SV turned track bike was gauges. I had a set of OEM SV650S gauges, but they wouldn't work with the GPTech Fairing Stay and Sharkskinz bodywork; at least not in their stock form. I’d read on the SVRider forum that several folks had cut the tach out of the SV650 Naked gauges with decent results. However, as soon as I took the S gauges apart, it was apparent that this would not be possible as there is one huge circuit board that controlled the entire bank of meters.
So an aftermarket tach would be required. There are scads of aftermarket clocks available for motorcycles. Most of them quite dapper looking with all sorts of really cool features, however they come with a heavy price tag that far exceeded my miniscule budget – and I didn't feel that I really needed all those extra bells or whistles.
A quick trip to any autoparts big-box store will reveal a locked case filled with all sorts of tach alternatives for much more reasonable prices – but will they work on motorcycles with engine configurations outside of automotive 4, 6 or 8 cylinder’s. I needed one that would work on a two-cylinder vehicle.
The Harley Davidson catalogs have scads of tachometers that will work on two-cylinder vehicles, but the problem was that none that I could find would read up into the stratospheric (by HD standards) 10,000 rpm ranges.
Then a crafty racer on SVRider.com found one that looked very promising. The Sunpro series of tachometers come in a range or sizes, two backing plate color choices (black or white) with a programmable shift light; for a price that ranges in the realm of 50-bucks. Well within my shoestring budget. I got lucky and found one on ebay for a few dollars cheaper.
I chose the 3 1/2 inch Sunpro CP2012 (the CP2010 has the black face) and was delighted when it arrived in just one week and got my grubby hands on the directions. Not only does the Sunpro work on every cylinder configuration thinkable (including 3-cylinder triples) but it’s a mere four wires to hook it up: A red for positive, a black for ground, a white for running light and a green for “negative coil lead”. The unfortunate thing was the Suzuki SV650 wiring diagram didn’t think to mention a coil or a tach anywhere. Bugger me! I was going to have to figure this out on my own.
Knowing that the wiring harness at the front of the bike would surely hold the wire I needed, I started tracing all the colors to eliminate any that could not possibly be the right wire. My analysis revealed that only one wire could be the tach wire, I carefully did a dry hook-up realizing that if I was wrong it very easily could destroy my new piece of hardware. Fortunately I was correct and the tach sprang to life!
The tach wire and the ground wire were actually the easiest to hook up; the green wire from the Sunpro goes to the bike wire that is black with a yellow stripe and the black wire with the white line was a ground also going directly to the battery – so the black wire from the Sunpro went to that one; done deal. The rest were open for a bit of interpretation. The bikes red wire with the white line was positive, but was live even with the key off because it goes directly to the battery. The bikes brown wire is the running light, so it’s live when the key is on, and not when the key is off. The bikes yellow wire and white wire are the high beam and low beam respectively.
Originally, I plugged the Sunpro’s red wire into the bikes red wire, and the Sunpro’s white wire (the tach light) into the brown wire but then the tach was awake all the time even though the Sunpro’s running light would turn on and off with the key. I wanted to plug the Sunpro red wire into the bike brown wire (the running light), but that left the tach’s running light eliminated all together which is quite fine for a track bike, but I finally just plugged the tach running light into the high beam wire – so the tach would illuminate (if I ever needed it to) when I switched the high-beam on. Confused? How ‘bout this:
| Tachometer | Bike |
Red (positive) |
Brown (running light) or Red/White (continuous live) |
Black (ground) |
Black/White Stripe (ground) |
Green (negative coil) |
Black/Yellow Stripe (tachometer lead) |
White (running light) |
Brown (running light) or Yellow or White (high/low beam) |
Then it was only a matter of properly mounting the new meter and tucking everything away. The GP Tech Faring Stay came with a cute 3 ½ round bracket for just such a purpose. Wanting to eliminate as much vibration as I could, I purchased some vacuum line and split it down the edge and used it as a barrier between the bracket and the tach. Then I mounted the included tach mounting hardware to the fairing stay using two machine screws and some nylon spacers (to further dampen vibration) and it was properly fastened up firmly.
The tach needle is smooth and follows the engine speed accurately, but does appear to read about 10% optimistic as the bike hits the 10,000 rpm rev limiter after the tach needle has gone past the 10,000 mark on the face. That’s okay with me, as Yamaha has “optimistic” tachometers themselves. Setting the shift light is a total breeze, I set mine to about 9,000rpm (closer to 8,000rpm actual) because according to the dyno, the SV is done making good power by 9000 rpm – so by the time I see the light, I can shift and stay in the power.
The only real weak aspect of the tachometer is weather worthiness. Buttons going through the glass face and wires coming out the back do not instill much confidence in its ability to live in a wet environment. For me, the bike spends 90% of its life inside and the other 10% that its outside is 90% dry. If this item were to be retrofit to a street-going vessel I’d have some concerns. For my needs, this tach fit the bill perfectly and for the price, even if it only lasts a couple of seasons, I won’t loose any sleep over buying the same unit twice.
While the Sunpro looked really nice on the bike, by the end of the first lap the needle had bounced out of place and vibrated uselessly between the shift-light and the black set buttons. A fast run up to near red-line would bounce the needle back out to where it belonged, but the vibration of the bike was too much for the tach. The shift light did illuminate at about the place I wanted it to, but it is not near bright enough to be noticed while outside during daylight hours. I thought about pulling the tach off or at least unplugging it, but never got around to it. Instead, the tach had pretty much stopped functioning all together by the end of the first day of use.
In other words, do not bother with this mod. It is a waste of time. The gauge now works only to look really nice on the bike and serves no other purpose than to be a constant reminder of its failings. Instead check out what we found about the Trail Tech Vapor Motorcycle Gauge.