75' Johnson 25hp first run

[Kajun37]

this is my first complete rebuild...and this is the first time i started it up..its knocking real bad...i'm guessing that the timing is way off? what would cause this knock?

also it seems to be running hot, i couldnt hold my hand on the powerhead for long, but it seems to be pumping water good? it had water coming out the exhaust hole and 2 holes in the bottom frony on the leg..... it has the old impeller on it though...i have a new impeller to put on it and will do so before i start it up again.

when i bought it($100), it was completely frozen..had to take it apart to get it unstuck.....i had the cyl's honed and put new rings on it, rebuilt carbs, put new condenser and points and 2 new coils on it, new fuel lines, new spark plugs...so far i got approx. $400 into it.

here is the video of the first time i start it up ...any ideas on the knock?

http://www.youtube.com/watch?v=FwFQ...s.iboats.com/newthread.php?do=postthread&f=24




before and after pics....

 

[tashasdaddy]

Re: 75' Johnson 25hp first run

sound like it is running on one cylinder. have you check compression and spark, after rebuild. did you throughly clean the carb, and rebuild?

 

[Kajun37]

Re: 75' Johnson 25hp first run

yup i got good compression and a strong 7/16 spark on both...carb was taken completely apart and cleaned good and carb rebuild kit put on it..

 

[R.Johnson]

Re: 75' Johnson 25hp first run

From the look's of all that rust, and the bottom piston, what did the rod, and crank bearing's look like?

 

[Kajun37]

Re: 75' Johnson 25hp first run

there was no rust behind that piston...rod and bearings looked great..

 

[R.Johnson]

Re: 75' Johnson 25hp first run

See if that knock is the flywheel hitting the coil heel's, does the stator plate seem to jump in time with the knock? You did torque down the flywheel?

 

[R.Johnson]

Re: 75' Johnson 25hp first run

Is that bottom piston damaged, or is that just rust I'm looking at? You said you had the cylinders honed, was there any damage to the wall's, or were the cylinder's measured? With all that rust you would not see the stamp on top of the piston, you don't have a standard piston in a over size bore?

 

[Kajun37]

Re: 75' Johnson 25hp first run

i will check the stator/coil next time i run it..the bottom cyl looks much worst that what it actually was...the cyl walls and piston was fine after honing and cleaning, they are the std original pistons....heres a pic...

 

[jaxbchangler]

hey did you ever find out what the problem was my is doing the same thing its a 1974 evinrude 25hp

 

[GA_Boater]

Jax - He's not going to tell you. The OP hasn't been back since 2008. Please do not reply to threads inactive for 3 or more months. Thanks.