Bf40 performance

"i have this model on a zodiak

"i have this model on a zodiak purchased from florida 2 years ago. have been having upper rpm range difficulties. runs great at idle up to about 2500 rpm. when between 3800 and 5500, running for not that long a time, it will loose cylinder #1. i will come back to idle, shut engine and restart. most of the time this resolves till the next occurrence. sometimes i have to restart multiple times. honda certified service rebuilt carbs, flushed fuel tank, tuned, swapped coils to no avail. he is now thinking it may be a bent valve that is intermittently sticking which is a lot of time and $ to repair. any other thoughts from anyone?"

Or a dodgy plug lead or a crac

Or a dodgy plug lead or a cracked sparkplug covery thingo. Those things seem to go and work intermittantly

"thanks for your response. plu

"thanks for your response. plugs were rotated. also when we swapped coil 1 with 2, the plug wire goes with it. again, still loosing cylinder 1. any other thoughts?"

"If a valve is bent the compre

"If a valve is bent the compression will be down on that cylinder all the time.
Since you've eliminated the ignition, that leaves a fuel problem. Either a top carb fault or top carb fuel starvation. Why not kill the engine when the fault is there & undo the top carb drain screw & see what comes out? maybe no fuel or a drop of water, etc,} then chase the fault.
Spraying "engine start" into the top carb intake while the problem is there will also confirm a carb or fuel fault."

"great ideas. thank you. i wil

"great ideas. thank you. i will post after i try them. compression is equal in all cylinders. also, the honda mechanic thinks a slightly bent valve can stick intermittently like this when engine running hot and under load. when i come back to idle and it cools for a moment with no load and/or restart, it frees up."