jw-17 low compression??

[nwcove]

a friend of mine came across his fathers jw-17 that was sold at a yard sale 10 years ago or so. he wants to get it running like new, but his mechanic tells him that the 60psi compression in both holes is to low for the motor to be a reliable runner. 60 is on the low side, but that little motor should start ok, idle ok etc at 60psi???

 

[Crosbyman]

Re: jw-17 low compression??

a friend of mine came across his fathers jw-17 that was sold at a yard sale 10 years ago or so. he wants to get it running like new, but his mechanic tells him that the 60psi compression in both holes is to low for the motor to be a reliable runner. 60 is on the low side, but that little motor should start ok, idle ok etc at 60psi???

just clean the carb, change impeller, clean the cap vents (2) if any on the JW (look real closely 2 small holes under the washer)
replace oil the the gears and run it.

Forget opinions for now you have nothing to loose anyway. great little motors but it may need new coils points condensers
certainly coils if running on originals .. probably all cracked up .

looks at site for a great article on fixing JW,s

http://www.outboard-boat-motor-repa...Johnson 3 HP 1952-1967 Carburetor Tune-UP.htm

p.s. tank screen may be clogged...clean for good fuel flow to carb

 

[HighTrim]

Re: jw-17 low compression??

At 60 psi, she is getting tired, even for a little JW. Ive tuned a few for guys that were in the 75 to 80 psi range. I have never tried one that low before myself.

Depends on the gauge of course, but Im sure the mechanic would have a quality gauge.

Throwing the money at it for a full tune up may be beating a dead horse as they say.

Now did he pull the head and determine the reason for the low compression? If it is simply an original head gasket, or even partially stuck rings, I would proceed. If the bore is worn to the point that the ring end gap is to big, and it needs to go oversize, might be easier to find a donor powerhead.

 

[nwcove]

Re: jw-17 low compression??

not sure what was done to the little motor, but the mech told the owner that 60psi was to low to bother spending money on it. my concern is...would it start,run, and be reliable at 60psi? jmo, but at 60psi, it may not start as well as it it could, but it should run ok. (i did offer up a free power head, 80 psi in both holes!)

 

[JB]

Re: jw-17 low compression??

60psi, taken with a correctly done test (see the Top Secret file), is fine for a rope start engine that hasn't been run in forever.

Quit sweating psi, respect the match, and get on with what might really need fixing.

 

[1946Zephyr]

Re: jw-17 low compression??

believe it or not, I have and had several good running J dubbs with 60 in each hole. Sure, they'll run better with more, but this is a 50+ year old motor and that isn't half bad

 

[lindy46]

Re: jw-17 low compression??

Soak the cylinders in some Seafoam for 24+ hours and I'll bet the compression will come up. Then once you get her running, do a decarb on her. She'll probably be fine.