Digital tach hour meter from OZ-USA - Honda Rebel Forum
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post #1 of 20 Old 07-17-2019, 10:53 AM Thread Starter
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Digital tach hour meter from OZ-USA

I have a tachometer i want to hook up to my 2003 Rebel250.
My problem is that the directions ask for "sparks per rotation"
Since the motor is twin cylinder and makes a wasted spark..what mode should i mode set the tach? 1 spark per revolution or 2 spark per revolution?
Im measuring RPM.
The wire to the tach wraps around one of the spark plug wires.
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post #2 of 20 Old 07-17-2019, 12:06 PM
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I would think two sparks per revolution since if there wasn't a wasted spark, there would only be half the sparks. But what do I know?

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post #3 of 20 Old 07-17-2019, 01:09 PM
 
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That's what I would think too.


Well if it revs up to 17,000 rpm, I think it'll be obvious it's on the wrong setting, .

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post #4 of 20 Old 07-17-2019, 06:16 PM
 
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The Rebel fires the spark plug on every revolution, even though it's a 4 stroke engine.

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post #5 of 20 Old 07-20-2019, 10:14 AM Thread Starter
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Im only concerned with the left cylinder. ..i have a tach to measure rpm...my question is how many times does the spark plug fire on the left cylinder per rotation.
Thanks.
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post #6 of 20 Old 07-20-2019, 10:42 AM
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Once per rotation, twice for all four strokes. It fires on compression and exhaust.

Keepin' all the left over parts. Gonna use 'em to build another bike!

'01 & '09 Rebel 250, '06 Ninja 250, '89 VN 750
Putting your bike year and model in your signature helps others help you!
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post #7 of 20 Old 07-21-2019, 11:17 AM Thread Starter
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Filtercontrol...ok then..what setting should I set the tach..1spark per rotation...2sparks per rotation?
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post #8 of 20 Old 07-21-2019, 12:13 PM
 
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Quote:
Originally Posted by Guba View Post
The Rebel fires the spark plug on every revolution, even though it's a 4 stroke engine.
Sorry I chimed in...

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Black '00 250
Red '07 250
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post #9 of 20 Old 07-21-2019, 12:46 PM
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As Guba first posted, each piston sparks once per rotation of the crankshaft, which is similar to a two stroke engine, even though it's a four stroke engine. If the tach reads one spark plug, I assume you would set it to two sparks since most engines fire each cylinder once per four stroke cycle (two rotations of crankshaft per cycle), and the Rebel does twice that.

Hope that doesn't confuse you.

Keepin' all the left over parts. Gonna use 'em to build another bike!

'01 & '09 Rebel 250, '06 Ninja 250, '89 VN 750
Putting your bike year and model in your signature helps others help you!
Here's how: https://www.hondarebelforum.com/f19/...re-121087.html
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post #10 of 20 Old 11-25-2019, 04:43 PM
 
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Quote:
Originally Posted by Guba View Post
The Rebel fires the spark plug on every revolution, even though it's a 4 stroke engine.
So should one set the tach at one spark per revolution?
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