Originally Posted by
coffeeguy
Water pressue was 13psi, it has open carbs, cowling has venting on the side and top rear to allow air in and out but not a direct path to the carbs ,stock 2 piece adaptor plate.. I have run the same set up off and on over the years but usually in the summer when corrected air is more in the 2000+ft range(based on alky motor experiences) The air was cold and crisp and I would guess in the 800 ft range. I now see this was an incident that was probably going to happen due to my inexperiece in tuning and had been posboned by dumb luck. The motor was strong. I will replace the piston an start high with the jetting . Thx to all the replies.