new guy needs old school help

[catfishmando]

hi everyone, im working on a 70' Johnson 20horse, starts fine, but idles like crap and will die and or run like crap when in gear, the rich/lean knob is missing and not sure where to start tuning
i should probably get a factory manual but the internet is just so much easier!!
thanks for any input

 

[CATransplant]

Re: new guy needs old school help

So, what have you done to it so far? How long have you had this outboard?

The symptoms you describe could be a carburetor problem or an engine running on one cylinder or an engine with low compression on one cylinder.

Check compression, then if that's OK (within 10% on the two cylinders), check the spark. If both are OK, it's probably time for a thorough carb cleaning.

The more information you can supply, the better the good folks here will be able to help you.

 

[catfishmando]

Re: new guy needs old school help

well i inherited it from my grandfather, and he owned it since brand new, and i just fired it up last week after sitting at our lake place for 15 years! lol
so it fired right up and then we noticed it wasnt spitting water, so i ordered the impeller for the pump, installed it tonight and it seems to idle fine as long as you have your hand on the handle, but as soon as you put it to shift mode and or put it in gear it will die out suddenly, and since im very very new to outboards im lost on how to tune a carb lol

 

[tashasdaddy]

Re: new guy needs old school help

you really need a service manual. with that motor, to make it reliable, you need to clean and rebuild the carb. inspect/replace the coils, condensor, points and plug wires. you have done the impeller. you can do this for around $150-200. it is worth it to get it reliable.

read these:
http://forums.iboats.com/showthread.php?t=158086

http://forums.iboats.com/showthread.php?t=294072

http://forums.iboats.com/showthread.php?t=244013

http://forums.iboats.com/showthread.php?t=167352

now ask any question you have. there are no dumb question, on iboats.

 

[wbeaton]

Re: new guy needs old school help

i just fired it up last week after sitting at our lake place for 15 years!

Sounds like you need to rebuild the carb. Send me your email address and I'll send you the carb pages from the 1970 Johnson 20 hp factory Service Manual.

You also need to check the coils. If they are cracked, sweaty or discoloured they are bad. Attached is a photo of some bad coils on a 1972 Johnson. You should also clean and set the points. Point gap is .020".

 

[catfishmando]

Re: new guy needs old school help

awesome, thanks for the tips guys
im going to get to work later today and see if i cant make some progress!