1980 75hp hesitation on throttle up from idle

[CBINMN]

1980 Johnson stinger 75hp J75trlcsa

I rebuilt motor ( top piston was melted motor had a lot of coking) with 3 new .020 wiseco pistons, all new bearings, rebuilt carbs (twice now) all new hoses and tank with vent open, new water pump, thermostat, poppet valves, spark plugs QL77JC4 gapped .030 currently nice tan color, 3 new coils and wires, new starter, new rectifier, did link n sync set at 750-800 rpm in gear in water 19 deg timing wot (5600 rpm) idles great, powers up well if I slowly accellerate past the hesitation point. Choking doesn't seem to have any effect on the hesitation. I am going to go back over link n sync again tomorrow to make triple sure I didn't miss something. Also I am still running 24:1 mixture ( about 4 hrs on rebuild). Any suggestions for something else I can check would be greatly appreciated.
The motor is on a 1980 16' aluminum crestliner open bow. It is currently mounted all the way down (cav plate just below bottom of boat) 13 1/4x17 prop
Chris

 

[tashasdaddy]

Re: 1980 75hp hesitation on throttle up from idle

did you remove and clean the high speed jets in the carb? it is behind the bowl drain plug.

 

[CBINMN]

Re: 1980 75hp hesitation on throttle up from idle

Thanks for the reply Tashasdaddy,

I did not remove them, but I did run wire through all of the jets. I used strand wire and added a strand until it would not go through anymore before and after soaking.
I think I have read every thread that has anything to do with hesitation or bogging on this forum. Going out to recheck link n sync again this morning.

Chris

 

[tashasdaddy]

Re: 1980 75hp hesitation on throttle up from idle

just running the wire thru. push the crud into the passages. this is a guideline, but was written for a 2cylinder motor. but the principle applies.
http://forums.iboats.com/showthread.php?t=244013

 

[CBINMN]

Re: 1980 75hp hesitation on throttle up from idle

I will attempt to make one of those today and remove jets as you say.

Thanks
Chris

 

[CBINMN]

Re: 1980 75hp hesitation on throttle up from idle

Ok carb jets removed and cleaned, sprayed carb cleaner through again to make sure all passages to throat were clear, went through link n sync again.
Took boat out today and I still have hesitation from idle to about 1800 rpm. I can't just gun it from idle and go or it will stall. Pushing choke just kills it.I can slowly throttle to 1800 and push to wot no problem. I am going to bring timing light and a friend tomorrow to see if it loses spark in that range for some odd reason. Also will take pulse tube off fuel pump to see if maybe small leak or something. I pulled the kids on the tube for 3hrs today just had to be slow taking off.

Chris