1971 50 Johnson... trubble plaining out.

[ponyPWR01]

I'l try to explain the best i can. I have a 1971 Johnson 50 horse. The lower unit was broken when i got the boat. I put in a rebuild one myself, im 21 years old and learning on my own... Lower unit works good. but i can't plain out the boat! i don't understand why? I have a 16foot Trihall. small boat, The 50 horse should plain out fine... The boat Idols awesome. i can put rpms all the way up to 5000 fine in Neutral. but when i go full throddle it idols down and wont let me get above 3000. why??? so i thought it was the carberators? i took both apart and cleaned out. now on the top carb the hmm little thing at the bottom of the float. pin/needle/seed? was sticking a bit. so i cleaned that out really good and it didnt seem to be sticking anymore. i used a air hose also when cleaning out the carbs. put all back together and still same thing. cant get above 3000 when under a load! but at nutral it runs awesome....? I went to a prop shop and got a differnt prop too. a 15 i think. so its one used to get out of the hole quick. im outa of things too try. can anyone help me? i need it for a trip on thursday and any help would be great. im new to this site, and new too my boat. Thanks a bunch.

 

[larky]

Re: 1971 50 Johnson... trubble plaining out.

ok, to start, do a compression test. you can buy a compression gauge from a sears store. they go for about $25-30. let us know what you find. next is a link and synk per an omc manual. now that I think of it the first thing and the least expensive is to check your boat and see if it is water logged. check the flotation foam for saturation.

 

[jedimaster]

Re: 1971 50 Johnson... trubble plaining out.

Could just be too much prop, what pitch prop is on it right now? May be too much weight in the back(water logged transom) etc...

 

[ponyPWR01]

Re: 1971 50 Johnson... trubble plaining out.

hmmm i don't think its water logged. i mean it's been in the garage for about a year now. How do i know what compression it should be at? i'v been told it could just be spark plugs? is this true? i mean i checked them when i put a thermastate in it and they seemed fine. i have a new gas tank, new gas line from tank to fuel pump, new gas lines from carbs, and new gas. could it be my fuel pump? i mean it runs good at idol and in nutral. its just under load. I talked to a the guy that sold be the prop, and he sold me one that is suppost to be on a 115 hrs Johnson. he said it would work and gave me a spacer for it too work, he also said it was a prop for getting outa the hole. i don't know, do you think thats my problem? i don't want to spend 150 dollars on a new one. what do you think
?

 

[larky]

Re: 1971 50 Johnson... trubble plaining out.

check compression, some meters differ, but as long as they(each cylinder) are within 10% of each other, it should be fine. from your descripition of what has been done, a compression test should be next.

 

[steelespike]

Re: 1971 50 Johnson... trubble plaining out.

Run the motor and feel base of the plugs if one isn't firing it will be cooler
and slower to heat.