1972 johnson 25 hp seahorse shift problems

[Tahiti warrior 502]

Hello I just bought this little 14 foot fishing boat with a 72 Johnson 25 hp, it runs great fires right up and goes right into reverse. It also acts like it goes into forward but if its under any load at all it pops into neutral.... I dont know much about these little motors but I tore the bottom end apart and the gears all look good. No major rounding or anything. Is there some way to adjust the shift linkage? Do I need to rebuild the bottom end?? Thanks for any insight!

 

[Crosbyman]

check shift link to make certain both ends of the 2 part shift rods are well inserted in the link holding them together l see access port lower exhaust section ...check shifter on top

 

[racerone]

Perhaps try another prop.---Hub in the prop might be slipping.-------The notches on the shift rods MUST line up before bolts are put in.----And shift action can be adjusted at the shift lever.

 

[F_R]

Hello I just bought this little 14 foot fishing boat with a 72 Johnson 25 hp, it runs great fires right up and goes right into reverse. It also acts like it goes into forward but if its under any load at all it pops into neutral.... I dont know much about these little motors but I tore the bottom end apart and the gears all look good. No major rounding or anything. Is there some way to adjust the shift linkage? Do I need to rebuild the bottom end?? Thanks for any insight!

Does "pops into neutral" mean the shifter actually pops back to neutral position? If it does, your clutch dog likely is badly worn out,

 

[Tahiti warrior 502]

Does "pops into neutral" mean the shifter actually pops back to neutral position? If it does, your clutch dog likely is badly worn out,

It mostly feels like it doesnt fully engage

Perhaps try another prop.---Hub in the prop might be slipping.-------The notches on the shift rods MUST line up before bolts are put in.----And shift action can be adjusted at the shift lever.

I will check the linkage and make sure its correct

 

[oldboat1]

Can help to slightly open number 58 (Crosbyman's diagram) with a bladed screwdriver.

 

[Tahiti warrior 502]

Thanks guys I adjusted the shift linkage and got it to work. Problem is the boat won't go past half throttle under load. It revs up fine out of water but won't even get on plane under load. Starts quick and idles nice... maybe a jet plugged up in carb? Thanks yall

 

[racerone]

I would say it is running on just 1 cylinder.----Trouble shooting will find the issue.

 

[F_R]

I would say it is running on just 1 cylinder.----Trouble shooting will find the issue.

Yep, agreed.

 

[racerone]

Not saying that it is running on just 1 cylinder.-----But these motors have a dual ignition system.----Very common to lose spark on one side.----And to a novice they sound wonderful running on 1 cylinder.----A wonderful motor that 72 model 25 HP.-----It be 50 years old and with common sense care it could last another 50 years.

 

[Tahiti warrior 502]

I appreciate the insight! I'll check the coils and sparkplugs! I just got new gear oil and water pump installed and got the shift linkage properly adjusted so a couple more tweaks and it will be good as gold.

 

[Crosbyman]

old style coils what is the resistance boot to ground values on both plugs wires.

 

[Tahiti warrior 502]

Could this crack in the coil be the reason I'm not getting spark

 

[racerone]

On more than one occasion have I seen the bottom of those coils burn through.----Spark takes path of least resistance and jumps to ground.----Does not want to jump gap in plug as it takes more effort to do so !