50 HP Bogging

timbo65h

Cadet
Joined
Aug 5, 2007
Messages
7
I have a 1975 50 hp johnson. It idles fine and takes throttle out of water hooked up to the muffs but when I put it in the water it just bogs when I give it throttle.(when in gear). It has 120 psi on both cylinders and I built the carbs, fuel pump, replaced spark plugs, primer bulb, gas lines(all gas line from tank all the way to the carbs, I used 3 different gas tanks. The only things I know left are the stator and the reeds. Can anyone help please the boat is just sitting.
 

david_r

Lieutenant Junior Grade
Joined
Aug 11, 2008
Messages
1,118
Re: 50 HP Bogging

welcome to marineengine!

was this an existing problem you were trying to fix with the carb and fuel pump rebuild?

did you do a link and sync?

when you rebuilt the carbs did you adjust where the cam meets the roller?

if you get the roller too close to the throttle cam it will add gas befor it advances the timing.
 

timbo65h

Cadet
Joined
Aug 5, 2007
Messages
7
Re: 50 HP Bogging

Yes it was an existing problem. I always run the gas out of my carbs before I take to boat out of the water due to the lack of use with this particular boat.(to keep gas from gumming up int the carbs) I left it running at the ramp went to get in the truck and when I come back it was running out of gas. When I put it in the water the next time this started. I move none of the linkage, allI did was disconnect it. I did not mess with the timing. I was thinking the stator was bad but I was going to check with someone who may know as these parts arent cheap.
 

david_r

Lieutenant Junior Grade
Joined
Aug 11, 2008
Messages
1,118
Re: 50 HP Bogging

are you getting good spark? does it jump a 3/8-7/16 gap with a good blue spark?

do you have a timing light?

if so you can hook it to each plug wire in turn to see if you are still getting spark when your motor bogs.
 

timbo65h

Cadet
Joined
Aug 5, 2007
Messages
7
Re: 50 HP Bogging

Yes I have a timing light and the engine never skips it is always hitting on both cylinders. It just runs like you are trrying to plane out a 1/4 throttle.
 

timbo65h

Cadet
Joined
Aug 5, 2007
Messages
7
Re: 50 HP Bogging

Yes exactly like that. That looked similar to the sheet that came with the kits. I have replaced every fuel component so far. If I havent then please name it. I only know of the reeds being the only thing fuel related I havent replaced and the symtoms have not changed. Had a friend with a 70 3 cylinder it would run good and then start doing the same thing mine is, then it would run good for a while and then do it again. He replaced the stator and it fixed it. It acts to me like the spark advance is not working. I refuse to take it to a shop because there are only so many things that can be wrong with a carbed 2 stroke of that year model.
 

timbo65h

Cadet
Joined
Aug 5, 2007
Messages
7
Re: 50 HP Bogging

I have let this boat sit for a while now cause i got tired of fooling with it but it still has the same ol problems. Runs great on muffs I havent put it in a drum of water yet but when in the lake it just boggs a wide open throttle. When it warms up I am going to take it to the water and get someone to drive while i fool with it. i will say these engines are the most agrivating thing to work on if you dont live on the water.
 
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