Originally Posted by Michigan Mike
If the fuel filter has some age on it I'd still replace it just to be sure ... shouldn't cost much. Seems like it might be possible for a partially clogged filter not to let enough fuel through to run both motors at high speed.
But, as someone else said, it's starting to sound like the carb may need cleaning. Here's a way to check ... when the back engine starts to falter, try choking it a little bit. If it picks up speed with this richer mixture it may indicate that the carb jets need cleaning and/or the air mixture needs adjusting. This would at least confirm that it's probably a gas problem.
Hope that helps ...
Mike, the carbs on these engine have no mixture/high speed/low speed adjustments, just idle. I raised the fast speed and that cured the problem of the rear engine dying out when idling.
Engine stumbling problem has been resolved, I believe.
I picked a a Walbro WYK-58 carb. Throttle fits, carb bolts on but ports don't match. Need to find the right manifold.
Does anyone know where I can find the matching manifold?