Topic: RE: Interesting Observation on timming

[chewbacca5000]

Did a couple tune up lately point bikes, cb400f and a cb550 and what I found was quite interesting.

On both bikes I could not get them to time up properly and my timing light would not flash correctly.  It would only flash intermittently.

What I found was that the fuel level was too high fouling the plugs.  Corrected the fuel height and all is well.  Timing light flashes properly and was able to get right on the F mark.

The ignition system is not always to blame.

[Deltarider]

Strange. Did you observe polarity when you connected the induction clamp?

[chewbacca5000]

Strange. Did you observe polarity when you connected the induction clamp?

I had the clamps on right positive and negative.  I never observed this before as I am able to get my carbs near perfect first time to have the correct fuel level.

The only thing I can deduce is that too much fuel = misfire / plug foul and it keeps it from sparking.  You can actually see it on the timing light.  Pretty cool.

[Scott S]

 Just witnessed this yesterday. CalJ gave me phone support and figured it out. I would have SWORN there was something wrong with the 2/3 side of the ignition system.

[mrbreeze]

Yes......it is pretty cool when it does that. I've used a timing light for many years to find which cylinder had a miss. Back in the day they used to pull plug wires one at a time. If you pulled a wire and the revs didn't drop.....you just found a cylinder that isn't contributing. Old engine analyzers had the cylinder cancel function that did the same thing or you could watch the spark lines on the oscilloscope. Nowadays you get a code that tells you what cylinder has a miss (OBD2).

[chewbacca5000]

Yes......it is pretty cool when it does that. I've used a timing light for many years to find which cylinder had a miss. Back in the day they used to pull plug wires one at a time. If you pulled a wire and the revs didn't drop.....you just found a cylinder that isn't contributing. Old engine analyzers had the cylinder cancel function that did the same thing or you could watch the spark lines on the oscilloscope. Nowadays you get a code that tells you what cylinder has a miss (OBD2).

Thanks for posting.  Nice to learn something new.