Pinging (spark knock) at 2500 - 3500 RPM

[51Duck]

Hi All,

I'm getting an odd pre-ignition ping at between 2500 and 3500 RPM. It's most pronounced when slowly moving through that range. If I go to full throttle it seems to quit. I have proven it is spark knock by adding octane booster, it goes away entirely. 91 Octane doesn't clear it so I am going to try to correct it. I am at 4700 feet and do not have the high altitude jet kit, but I believe that its purpose it to lean the mixture so I don't think that is it. Carbs were gone through completely about a year and a half ago. Idle is perfect, carbs feel and sound synched, full throttle is no problem, gas mileage is good. I am thinking maybe a carb diaphragm could have a small hole? Anyone else have and fix this before? Any advice would be very appreciated, first step tomorrow is to re-check carb sync. Have already done a visual and found no vacuum leaks....

[Mr Jensee]

If it turns out not to be a mechanical problem go to 93 Octane. The purpose of the higher octane is to retard spark. I hope you can track down the source. You might consult with Carl Leo before you attack the carbs.

[cranky]

... + 1 ... NOT a wrench, but from what I've read, something has the
timing mucked up, advanced too far..... Hope Ya find the culprit!!!!

[Barry]

Is yours a California model? Mine would sometimes behave as you describe. I had Carl Leo rebuild the carbs. He does way more than just change jetting. He also changes the needles and polishes the slides. He does even more to ensure you get a trouble free product from him. You would not believe the performance improvement from his secret changes. Warning: Your fuel mileage will go down, but smiling even more with each ride.