Rev Counter/Engine Misfire

I have an 83 Kz550 Spectre Shaftie.

I was setting off from work, the bike started fine (choke fully out) - about 10 seconds later, the Rev counter stopped working, the engine became noisey and not a lot of power. I coud also smell fuel. It doesn't tick over nicely. (Though normally does) The bike is as though running on only a couple of cylinders. I was also low on fuel, though suspect that this has nothing to do with it.

Is this due to the REV counter? How can I test it?

This is the 2nd time I've had this. The last time, I left the bike overnight and the fault rectified itself.

Any ideas?

Thanks

screwfox

Post edited by: screwfox, at: 2008/02/12 12:20

screwfox wrote:

I have an 83 Kz550 Spectre Shaftie.

I was setting off from work, the bike started fine (choke fully out) - about 10 seconds later, the Rev counter stopped working, the engine became noisey and not a lot of power. I coud also smell fuel. It doesn't tick over nicely. (Though normally does) The bike is as though running on only a couple of cylinders. I was also low on fuel, though suspect that this has nothing to do with it.

Is this due to the REV counter? How can I test it?

This is the 2nd time I've had this. The last time, I left the bike overnight and the fault rectified itself.

Any ideas?

Thanks

screwfox<br><br>Post edited by: screwfox, at: 2008/02/12 12:20

Shooting from the hip:

Is the tach electronic drive (as opposed to cable drive?)

This sounds like maybe an electrical problem where you could have lost a coil output and the two cylinders if fires. That would send a lot of raw gas out the pipe and run really badly.

I agree with bountyhunter. It makes perfect sense if your rev counter is electronic, because it will use the same signal that triggers your coils to indicate RPM's.

(I am assuming your rev counter uses the ignition trigger to the coil, and not the spark plug wire after it.)

No signal to the coil equals you loose one coil (no spark on two cylinders) and the rev counter at the same time, and yes, it will be loud, and have no power.

I'd be surprised to see the rev counter itself be the problem.

Start it again and see which of the four headers remain cold. Usually cylinder 1+4 will be paired, and 2+3. That will tell you which coil is not getting triggered.

Or follow the trigger wire from your tach to the coil in question.

Thanks, I'll take a look. Is it likely to be a connection issue or a dodgey coil itself?

screwfox wrote:

Thanks, I'll take a look. Is it likely to be a connection issue or a dodgey coil itself?

No way to tell from here, but flaky coils do get worse when they get hot and "heal" when they get cold. I just had to replace my coil because it misfired after about ten minutes of running.

screwfox wrote:

Thanks, I'll take a look. Is it likely to be a connection issue or a dodgey coil itself?

Like bounty said hard to tell from here. Gut feeling sez internittent short. I am guessing it's the trigger connection to the coil rather than the coil but there is only one way to find out. I would first check and make sure the connectors to the coil are good (not broken/disconnected/corroded) that may be it right there.

Your 1,4 coil has a black wire to it. That splits off to the igniter and the tach. Disconnect the branch to the tach. If the bike then runs normal, the tach is shorted, or the wiring to the tach is shorted.

If the bike still runs on two cylinders, try to connect that tach wire to the green wire going to the 2,3 coil. If the tach works then, you know the tach is definitely not the issue.

Luckily, with swapping parts and flipping the pickup rotor, you can troubleshoot the problem without having to buy anything. The first step is to disconnect that tach wire to eliminate it as a possibility.

Thanks for the replies. I'll give it a go when I can get the bike in the garage this weekend.

Cheers