Custom/Hybrid Fouling plugs

[Brian_216]

I have a jetmaniac 718 motor Everything came set up, at sea level that is. I am however at 1030 feet. I left everything set the way it came, 1 turn on the lows, 1.5 on the highs. I did some tuning on the low speed screws, it was loading up pretty bad at first. I ended up going to just under a half turn out on the lows and its happy, anything less and it goes lean and shuts off when pinning the throttle after idling for a short time. So Im confident the lows are where they need to be.

However after a weekend of riding, Im left with 2 fouled plugs, one cylinder would not even run. I dont have a tach right now, and I havent touched the highs for fear of burning it down. Now considering I had to go to half of the setting that works at sea level to get it right on the lows, would the same apply on the highs? I dont run this thing WFO, its just a quick brap to jump a wake. Looking for some advice. Once I upgrade to a mag pump, I will be borrowing a tach to see what Im turning the prop at to get that dialed in and help find me the right prop.

 

[Waternut]

If you're under a 1/2 turn on the low, I'd be tempted to say you should rejet the low. I fought a similar issue for a while this summer. I found a perfect happy place in my tuning that gave awesome power off idle and on up to the top but if I let it idle or run below 1/4 throttle for more than 30 seconds, it would foul the plugs. I had to go down a half jet on the front carb and a full jet on the rear carb plus I had to raise the pop off.