Old style auto engine analyzer...need answer fast

I have an old style engine analyzer that has a positive and negative cables for power from the battery, and an alligator clip that attaches to the coil for RPM measurement. I would like to use this on a motorcycle, should I select 4, 6 or 8 cylinder for the most accurate measurement?

How many cylinders does the motorcycle engine have?

What measurement are you interested in?

V twin harley sportster. Trying to set rpm at idle.

V twin harley sportster. Trying to set rpm at idle.

Select 4 and double the reading.

Thanks!

yeah , based on car engine knowledge, that would make sense… but doesn’t the motorbike fire off the sparks twice as often as needed, because they can’t be bothered having a half speed cog ?

Select 4 and see what the reading says.

Its either accurate or in need of doubling.

it depends how old it is, Harleys used to have “wasted spark” ignition but I don’t think they’ve done that ever since moving to fuel injection.

Forgive the question/comment, not really a motorcycle guy but still, every single motorcycle I’ve ever seen in my entire life had a built-in, factory tachometer on its ‘dash’…

Mine doesn’t, so there’s your counterexample. (note, not a picture of my actual bike, just a picture of the same model I found on the internet.)

This sporty I’m working on has no tach, and neither does my honda shadow.

Back to the OP, my buddy did not bring the bike over yesterday as planned. When I get to check the RPM at idle, I will update you guys.

Oh that’s right*!* The big chrome retro gauge on the gas tank is a speedometer not a tach. I assume this must have something to do with Harleys not being nearly as ‘revy’ as Japanese bikes?

Harley’s are a bit different. The two pistons are not opposed at 90 degrees or whatever with a heavy counterweight, each piston instead is connected to one pin on the crank, fires fairly close in sequence right after each other with a long pause in between. This gives them a lot of low end torque and their unique exhaust note.

Potatopotatopotato…

Whenever I see a Harley idling, I’m temped to tell the rider “I can tune that thing up for you so it runs good.”

trust me, they’ve heard it a million times. you’re not being witty or original.

Neither are bikers that run straight pipes. I’ve heard that a million times, too. You run a bike that sounds like that, you can stand to hear my “witty” remark again. It’s less annoying than hearing straight pipes night and day.