25HP Johnson No Start


Old 03-13-05, 07:15 AM
Visiting Guest
Posts: n/a
25HP Johnson No Start


Have a 25hp Johnson no start. Was running before storage 1 yr ago.

I've got spark, nice pretty and strong.

Fuel is flowing and the carb looks clean. I tanked it and blew all the passages, everything seems to be flowing.

Fuel is fresh, good 50:1 mix.

Great bulb etc. from tank.

Compression? Sounds ok, haven't checked it or ever thought of checking a 2stroke for comp. b4. Anything special here?

Timing? Not sure if it is ok or not. It was running b4 storage so I ASSUME (OOPS!) that it hasn't moved.

I'd GREATLY appreciate any suggestions...

Sponsored Links
Old 04-02-05, 12:16 PM
Join Date: Nov 2004
Posts: 74
No start 25hp Johnson

Probably compression a factor since this is a 1969 model year engine.
I have the manual for this engine - the variance should not exceed 5 psi between cylinders on 1 - 40 hp Johnson outboard. I can not find the oem compression as new.

Timing may be out.. set points (after replacement or filing) at .020 gap.
But synchronization is not easily described. Best to get a Seloc manual
http://www.marineengine.com before proceeding. Timing is set by adjusting the critical time when the throttle shaft (in the carb) actually begins to move AND when the cam follower hits the designated position (between the marks on this engine). I cannot describe this to you, but the manual ($25) covers 1.5 to 40 hp Johnson very well with pictures of these locations.

Darn thing has reed valves - this probability is of course covered in the manual.



Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Thread Tools
Search this Thread
Display Modes