85 Johnson 40 Bad Trouble

S

starrider

Recruit
Joined
Mar 18, 2009
Messages
4
Alright folks, I joined this forum last night to ID a motor and ya'll came through for me. Went out tonight and checked the compression. Bad News. The top cylinder read about 127-129 the bottom cylinder read 50-55. I'm good enough with cars to know I've got a problem. So If I could get some opinions and ideas on where to go now I'd be in you debt.
Main problem is no start. However I still think the fuel delivery is messed up. The boats delivery is OK. But When it gets to the carbs something is out of whack. I'm thinking the floats are gummed up or never been adjusted or for that matter even checked. So it's Flooding to beat the band.Checking that's next.
Johnson 40 1985. Any ANY! Help would be greatly appreciated.
Thanks All
 
T

tx1961whaler

Vice Admiral
Joined
May 31, 2008
Messages
5,197
Re: 85 Johnson 40 Bad Trouble

Tackle the compression issue first.
I'd take the head and exhaust covers off and inspect the cylinders and piston. If they're OK, then change the head gasket and recheck the compression.

If that works, then you can look at the carb. issue.

If the cylinder is really messed up, you may be looking at a new powerhead....
 
F

F_R

Supreme Mariner
Joined
Jul 7, 2006
Messages
28,226
Re: 85 Johnson 40 Bad Trouble

You are totally wasting your time worrying about the carburetors till you find out what is wrong with that cylinder. A brand new carburetor won't make that cylinder fire.

However, a dirty or gummed up carburetor can wreck the cylinder (no fuel = no oil) and could be what caused all this grief in the first place.
 
S

starrider

Recruit
Joined
Mar 18, 2009
Messages
4
Re: 85 Johnson 40 Bad Trouble

Thanks Guys! I Know I shouldn't be bothering with the carbs just yet, but I figure it's got to be done anyway, and if it turns out to be the powerhead I'm going to have to save up for it anyway so why not look at what I can in the meantime? Anyway your advice is invaluable to me and I've got my better half going to pick up a head gasket. Found some parts local so I'll give that a shot. Thanks tashasdaddy for saying it's a great motor. Right now I can use all the encouragement I can get! Look forward to talking with ya'll again
 
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