1984 Johnson 90 hp

[khoward]

I have the above motor and I'll be honest, it's really been neglected. I took it to the lake this afternoon, backed it in, and got it started and let it idle for a good 20 minutes. Aside from all of the smoke, it ran ok. As far as I know, it's never been de-carbed. Can I hurt the motor by doing this now if it's never been done? I'm planning on replacing the lower unit grease and then I'll replace the spark plugs after decarbing. Anyone have a suggestion on plugs? I don't have the owners manual and need to know the gasil mix as well. I've already learned a lot from reading this forum. Thanks everyone.

 

[rickdb1boat]

Re: 1984 Johnson 90 hp

It would not hurt to do a decarb. It would also not be a bad idea if this motor has sat for any length of time to remove and rebuild the carbs. If one carb is clogged at all, it can lead to a lean condition in that cylinder and burn it up quick. The fuel/oil mix is 50:1 or about 1 pint of TCW-3 oil per 6 gallons of fuel. Can you give us some more backround on the motor? Champion QL77JC4 on the plugs, gapped at .040 works best....

BTW- If you have not read this already, it is recommended...

http://forums.iboats.com/bbBoard.cgi?a=viewthread;fid=36;gtid=1035575 ] Click Here [/url]

 

[emdsapmgr]

Re: 1984 Johnson 90 hp

As a a preventative measure, I would also put a new impeller in the lower unit.

 

[khoward]

Re: 1984 Johnson 90 hp

Thanks for the quick replies. I don't have a whole lot of background on the motor. It's on a 1984 Tidecraft and suprisingly runs ok. I'll be honest, I'm not very mechanically inclined. But that being said, I'm a very quick learner and enjoy "tinkering" with this sort of thing. Can you give me more info on rebuilding the carbs? Is this tough to do or should I take it to a mechanic. Any idea on cost for do it yourself? I'm not wanting to sink a whole lot into this boat due to its age and I'm planning on buying new in the next couple of years. Any info is appreciated.

PS. The link you provided on awakening an outboard was a great read.

 

[Silvertip]

Re: 1984 Johnson 90 hp

If you plan to do any work on this engine yourself you are advised to obtain a service manual specific to your engine. It saves time, frustration, and can possibly save you a bunch of money by reducing the possibility of messing something up. If you don't want to buy one, check your local library as they often have them. Carb disassembly is not difficult. Disassemble them entirely. Soak in carb cleaner, ensure every passage is squeaky clean, blow out with air and assemble with new kits.