Author Topic: 650 tach drive on a 550 tach?  (Read 364 times)

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Offline 88BuckMeister

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650 tach drive on a 550 tach?
« on: January 22, 2024, 06:29:52 PM »
Ok, so hear me out before you stone me...

 As many of you know at this point because of the sheer amount of obnoxious questions I ask incessantly about the project I'm in the middle of, with the 650 cam I'm putting in my 550, I know it will not work with a 550 tach, so I did order the new tach drive. I know the tach drive fits in the stock housing. I also know that the tachometer does not fit inside of the receptacle for the 550 if I were to get a 650 tach…

What if I hook the 650 tach drive/cable up to the 550 tach? I understand the calibration will be different. I think I've seen the calibrated operational ratios on the forum before, I don't remember exactly what they were but I know that they will not sync up properly. it will however have something functioning in the meantime and prevent me from having inop things capped off all over the place...

I also know that I can ride a bike and listen to what it wants, what it likes, when it's winding too high, etc. What will be the end result if I hook the 650 cam tach drive cable up to the 550 tach? Rather than capping it off and having a loose cable hanging? Aside from an inaccurate tach reading, will it destroy the tach? Or is inaccuracy in calibration all we're looking at?  That's basically my question, will it just give an inaccurate reading, or will it actually destroy the tach?  To my knowledge the only difference is the gear ratio on the drive...

Offline grcamna2

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Re: 650 tach drive on a 550 tach?
« Reply #1 on: January 22, 2024, 08:33:37 PM »
I believe hooking up the 650 tach drive ratio/cable to your 550 tachometer will only result in an inaccurate rpm reading:nothing else.
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Offline bryanj

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Re: 650 tach drive on a 550 tach?
« Reply #2 on: January 23, 2024, 12:39:19 AM »
It will only destroy the gauge if its reading way too high so ends up pegged against the stop all the time and i dont think the ratio is different enough to do that
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Offline Tracksnblades1

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Re: 650 tach drive on a 550 tach?
« Reply #3 on: January 23, 2024, 07:20:08 AM »
http://forums.sohc4.net/index.php/topic,148490.msg1692538.html#msg1692538

Perhaps one of a few….? Reinventing the wheel….?

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