How many engine rotations per signal??

I just got an aftermarket tach put into my XJ900. I had almost no experience riding it before the new tach, and therefore do not know where normal revs SHOULD be.

the mechanics installed it; so I do not know exactly how it is installed, but it does have a setting called "Engine Rotations per Signal". the only settings I can input are: 0.5, 1.0 2.0 3.0.

Essentially if 1.0 is the correct setting, and you input 0.5, your RPMs will always read 1/2 of what they are suppose to be.

I tried a few of them, and reasoned that 1.0 sounded about right. However I have rode the bike to 13,000 RPM. Last time I was on the highway, I had it running around 110km, and it was revving at 9000RPM.

I'm thinking I should be using 0.5 engine rotations per signal, which would essentially half all my RPMS.

Can anyone with an early XJ900 post some approximate key speeds, vs. RPMs, and list the gear.

Ex.
5000RPM @ 100km/h in 5th.
or
6000RPM @ 80km/h in 4th.

 

Hi,

My 1985 XJ900 spins at around 4000rpm at 100kmh so maybe the 0.5 setting could be right for you considering that yours showed 9000rpm(!!??) at 110kmh.

Divide that by 2 and you get around 4500rpm at 110kmh.

Good luck.

 

These engines use wasted spark and dual ignition circuits. The result is one spark "event" per engine rev (as opposed to a non-DIS car engine, where you would get one spark per two revs at the plug and # cylinders / 2 spark events per rev at the coil).

So, for your setup, if I understand the documentation correctly, it should be 1.0.

Cheers,
Paul

 

I figured it out once and for all.

I had it set to 1.0, and took her on the highway. at 115km/h she was reading 11,000 RPM!

So I switched to 0.5, and tried again. 5,500. Much better. Thanks guys.