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SBT FUJI 780 motor
Premix fuel
Carbs rebuilt with new kits
Carbs set to factory specs
I finally got my new SBT motor set in, connected and running a couple of weeks ago. I had a scare during the break-in period because it seemed to miss out horribly. I checked the timing and it was OK and finally the engine leveled out and idles well since I went to the 40:1 mixture. It seems the problem was just a combination of the low throttle speeds (20% and 50% max on initial break-in) and the rich (32:1) mixture.
So here's my problem. I'm getting heavy smoke at idle. To start the engine I have to hold the throttle wide open. Then to accelerate I have hold it wide open until the carbs clear out. All three plugs have a very nice even, brown color so I know they are burning just right on the high speed jets. However, at idle this thing is loading up bad.
I have closed the idle jets down to one full turn, which has helped a little, but still if I idle for long I have to hold it full throttle until it clears out and takes off. So, can I close the idle jets down further or is there something else I need to check? As far as top end this thing is running great, but I'd like to get this bottom end/loading problem figured out. IF it's just a side effect of pre-mix I can live with that instead of worrying about the oil system.
KJ
SBT FUJI 780 motor
Premix fuel
Carbs rebuilt with new kits
Carbs set to factory specs
I finally got my new SBT motor set in, connected and running a couple of weeks ago. I had a scare during the break-in period because it seemed to miss out horribly. I checked the timing and it was OK and finally the engine leveled out and idles well since I went to the 40:1 mixture. It seems the problem was just a combination of the low throttle speeds (20% and 50% max on initial break-in) and the rich (32:1) mixture.
So here's my problem. I'm getting heavy smoke at idle. To start the engine I have to hold the throttle wide open. Then to accelerate I have hold it wide open until the carbs clear out. All three plugs have a very nice even, brown color so I know they are burning just right on the high speed jets. However, at idle this thing is loading up bad.
I have closed the idle jets down to one full turn, which has helped a little, but still if I idle for long I have to hold it full throttle until it clears out and takes off. So, can I close the idle jets down further or is there something else I need to check? As far as top end this thing is running great, but I'd like to get this bottom end/loading problem figured out. IF it's just a side effect of pre-mix I can live with that instead of worrying about the oil system.
KJ
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