Sendec Tach/hourmeter with twins

[swood 0]

I got my tach in the mail this week, and from the instructions (which are limited to the back of the blister pack) it works with most twins. I take this to mean twins that only fire each cylinder every other cycle. There is no switch on the device to interpret the signal, so it's best to test your engine first. One other note, the device uses a lithium battery for long life. It better be long because it's potted inside the device. When the battery runs out, you throw out the tack, I guess. Greg

[JP 0]

Greg, What is the model number of the unit you have? What kind of engine do you have it on? Is it reading correctly? What was required to install (2 holes for mounting bolts or holes plus a dashboard cutout)? Does it have the service reminder alerts? Interesting note. The unit Norther Hydraulics sells says the battery lasts 3 years. SenDec says their battery lasts 8 or 9 years. Thanks, Roy

[Guest]

"SenDec says their battery lasts 8 or 9 years." So what you're saying is, these things don't really last very long compared to the Simplicity tractor it's on? :)

[Kent 435]

Roy, I'm pretty sure the model number is 806-100. I don't have it with me right now, but that's the number that makes sense, looking at Sendec's web page. It's a surface mount with 2 screws (does not require a dash cutout), and has both the change oil and lube alerts at 25 hours. I actually plan to install it with velcro so I don't have to drill holes in the dash. I haven't used it yet, but it's for a 12 horse single cylinder, so I won't be able to test it for you on a twin. But thinking the design through, it has no way of knowing whether it's mounted to a twin or a single cylinder, and it works by picking up an inductive pulse from the spark plug wire its inductor is wrapped around. (can only wrap one plug wire if used on a twin--well, I guess if you really wanted to, you could wrap both, but it wouldn't make any sense to, unless you want 2X or 4X speed readings, depending on how the plugs fire) So, if the twin it's used on fires both plugs every revolution, this tach will display twice the actual speed. If each plug fires every other revolution like most 4-cycles (even if both plugs fire at or near the same time), it will read the correct speed. As far as the battery goes, I understand why it's potted, it's so vibration doesn't shake the electronics around and cause open circuits. This is a good idea for reliability, but it renders it a disposable item when the battery runs out. It really seemed like a good thing to buy, and I'm glad I have it, but to be honest I can't believe I spent close to $40 for an electronic gizmo that couldn't cost $3 to make. It is really way over priced. I could make this myself if I wanted to put the time into it, but time is precious right now... Greg