ok so i bought this boat earlier in the summer. needed some work but overall had good structure and it ran. ive gotten most everything finished with no problems until now. the boat has a 1985 Johnson 20hp J20ELCOS on it. it ran ok but could tell it definitely needed a carb rebuild. it ran but acted restricted, the primer bulb wouldnt get stiff and i could tell the float was out of adjustment, and really didn't idle all that great. while doing some research for parts i stumbled on some info about how to convert the motor to a little more hp and many people said it helped the motor to run better all together and idle better, which is what i needed. so when i removed the carb i found the intake was restricted as well as the inlet port to for the electric primer was broken. so i pulled the intake and had it machined to match the opening of the carb and also had the port repaired for hose from the primer. i rebuilt the carb after soaking it overnight in carb cleaner and blowing it out with a compressor. i found that the float was way out of wack and that also the slow speed needle had nothing to seal to like the piece that came in the new rebuild kit. after reassembling the carb and getting the intake back i reassembled everything with new gaskets. i now found that my primer bulb pumps up tight i have no fuel leaks and i was good to go. so i set the slow speed needle to 1 1/2 turns out from gently seated and put the hose on it in the driveway and started it up. this is where the problems begin. it would run but only if i gave it throttle and it was acting like a backfire and would not idle. i tried adjusting the slow speed needle as it says and couldnt get it to change. still having the "popping" effect and no idle. so i experimented and opened the slow speed needle way up and it seemed to get better but wouldnt idle. the only time i could get it to smooth out is if i put my fingers over the carb an choked some of the air off. so i figured i needed a bigger main jet to be able to adjust and compensate for the extra air i was giving the motor from opening up the intake to match the carb. so i came here and researched the part numbers between the 20hp and 30 hp. i found that they are all the same part number except the main jet orifice in the carb. even the leaf plates are the same and leaf stops which i assume is just like the reeds in a dirt bike. idk maybe im wrong. so i ordered the new orifice and replaced it and tried again. the results i got where that it will idle for a short time and seems a little better but still not right. so here i am. can anyone help? not sure what to do from here. any help would be greatly appreciated im at my wits end.
