Cylinder Bore Size ? Johnson 3hp '52-'54 JW-10

[1_Pull_Wonda]

Have a line on some oversized piston rings (part #203398 superseded to part #378414) for my JW-10. I have decided to go a head and rebuild the power head.

According to my parts list, the over sized piston rings are ?.020 O.S.?. I am assuming this means that they are .020 larger than the standard size. But, that still doesn?t tell me what size the cylinders need to be bored to. I believe, but am not positive, that the original bore size is 1 9/16. Can anyone confirm this ? If so, do I need to have the cylinder bored to 1 9/16 ? plus .020 ? Do the cylinders really need to be bored or is .020 such a small increase that honing the cylinders would work ?

Also, can anyone confirm that I don?t need oversized pistons ? Or that oversized pistons to replace the standard sized pistons were not manufactured ?

Alcan ? F_R ? Anyone else ?


P.S. I have 2 JW-10s. The one with the god compression is not being rebuilt.

 

[JB]

Re: Cylinder Bore Size ? Johnson 3hp '52-'54 JW-10

Yes. Original bore was 1-9/16".

I have seen a lot of JWs "rebuilt", but I have never seen one with worn out rings, much less pistons.

I have seen a few that were sufficiently abused to have scored cylinders and ruined pistons, but that seemed to have nothing to do with age or hours.

 

[1_Pull_Wonda]

Re: Cylinder Bore Size ? Johnson 3hp '52-'54 JW-10

The engine is definitely shot. If I remember correctly, the compression readings were around 50 or 60 psi.... pretty bad. Adding 2 cycle oil in combustion chambers did very little to increase these readings so, I am guessing that the cylinder walls are scored and/or the rings are worn out.

I believe the oversized rings that I will purchase are from OMC not a 3rd party manufacturer.

I'll disassemble and reassemble the power head but, a shop will do the boring. As long as I can tell the shop what the specs are on the oversized piston rings, you would think the shop has all the information, knows the information or knows where to get the information to complete the job. I don't think it is really my place to tell the shop how to do their jobs but, I have to at least give the specs on the new rings.

I understand how the cylinder walls could be scored. I think that a ring could go bad under too much heat or debris getting caught between the cylinder wall and ring but, how does a piston go bad ? Maybe breaking an edge when trying to remove the old ring ?

This will be the first time I'll have put new rings on anything so, It is definitely a learning a experience.

I found some interesting info when searching the forums but nothing for my specific for my application.

 

[R.Johnson]

Re: Cylinder Bore Size ? Johnson 3hp '52-'54 JW-10

First find the oversize pistons, have you looked for those yet?

 

[JB]

Re: Cylinder Bore Size ? Johnson 3hp '52-'54 JW-10

50-60psi readings are not unusual in healthy JW Johnnys, Wonda. Remember, you are using a recoil starter and the engine is cold.

 

[steelespike]

Re: Cylinder Bore Size ? Johnson 3hp '52-'54 JW-10

60 psi on these little motors is considered fairly good and a decarb treatment may raise it a little without a teardown.Buy some Sea Foam and follow the directions.

 

[steelespike]

Re: Cylinder Bore Size ? Johnson 3hp '52-'54 JW-10

60psi is considered fairly good on these little motors.A decarb treatment may improve it some.Just get some Sea Foam and follow the instructions.
oops,You would think I could get it right after 7,000 posts.

 

[1_Pull_Wonda]

Re: Cylinder Bore Size ? Johnson 3hp '52-'54 JW-10

R.Johnson gave me great advice by telling me to follow the piston.

Talked to a couple of different service and parts guys. They all said you definitely need .020 oversized pistons to go with my .020 oversized piston rings.

The earliest they could find a 3hp with a .020 oversized piston was 1962 part #277283. Part #277283 works with the following models JW23A, JW23M, JWF23A, JWF23M, JWFL23A, JWFL23M, JWL23A, JWL23M and probably more models than this. Not sure what year is of each respective model.

Part #277283 supersedes to #0383240 = .020 Piston Assembly w/o piston rings. They could not tell me what is in the assembly. Maybe it consist of the oversized piston and rod.....not sure.

Also found out.....

Standard Bore = 1.56 from 1952 (possibly earlier) thru 1984 (and possibly later)
Stroke = 1.38 1952 (possibly earlier) thru 1969
Stroke = 1.37 1970 thru unknown ?
The displacement also change but I not sure when. It is possible that displacement changed at a different time than the stroke change.

Part number #277283 should definitely work and therefore part #0383240 should work. It would be great if some could provide the original oversized piston part number and see and that superseded to #277283


Also, in case anyone wants this info?..

Piston Ring Standard Size (quantity 1) Part #203152 supersede to part #378412 (quantity 2).
Piston Ring Set .020 O.S. (quantity 1) 203398 supersede to part #378414(quantity 2).
Piston, Piston Ring, Rod Assembly (assuming quantity 1) 277165 Superseded part number unknown.
Standard Piston (quantity 1) Part #277166 supersede to part #432739 which comes with standard rings already installed.

 

[1_Pull_Wonda]

Re: Cylinder Bore Size ? Johnson 3hp '52-'54 JW-10

Edited my previous post.

 

[steelespike]

Re: Cylinder Bore Size ? Johnson 3hp '52-'54 JW-10

3hp production began in 52 My aftermarket service manuals cover 55-89
as near as I can tell bore and stroke and displacement remained unchanged
through the production run. these include 2.5 3,4 and 4.5.Surely design changes were made; Mix ratio was 16:1 through 58,24:1 59-63 and 50:1 64 on.It appears to me that piston clearances are the same to 68 or 69.
Piston pin diameter/clearance at least through through 72.
There must be rings or pistons and rings that will work in your motor.
Of course all this info is from after market manuals and they have been known to be wrong.
Is it fact that you need to bore?If you do bore use a shop that routinely
does outboards.

 

[1_Pull_Wonda]

Re: Cylinder Bore Size ? Johnson 3hp '52-'54 JW-10

steelespike?..thanks for the info and advice !!!

Made a couple of mistakes in my previous post.

1.) The earliest the parts and service guys could find a 3hp with a .020 oversized piston listed was 1964.

2.) I was told the following information was from an aftermarket source. This source may have been published in 1984 and that is why the specs end at that time. And as you said, ?they have been known to be wrong.?

Standard Bore = 1.56 from 1952 thru 1984
Stroke = 1.38 from 1952 thru 1969
Stroke = 1.37 from 1970 thru 1984
Displacement = 5.28 from 1952 thru 1984

Did you mean to say that the piston wrist pin diameter/clearance is the same from 1952 thru 1972 ?

I understand bore, stroke and displacement. What are piston clearances ?

Had an idea??..

If the original part number of a 1964 JW-19 standard size piston is the same number as a 1952 thru ?54 JW-10, then I conclude that the 1964 JW-19 oversized piston would work.

So, the question is?what is the original (not supersede) part number of 1964 JW-19 ?

My original part number is 277166.

 

[steelespike]

Re: Cylinder Bore Size ? Johnson 3hp '52-'54 JW-10

Piston skirt clearance 0.0013-0.0025 55-68 ring end gap 0005-0.015,55-68
side clearance 0.001-0.0035 55-69 Probably same 52-55 but I don't have that info.Piston pin specs are 55-72 I don't have before 55 or after 72 specs.
Again I wouldn't be surprised to find 52-54 the same.
You might pose some of these Qs/thoughts over at the antique outboard motor club www.aomci.org.

 

[OLDIRON]

Re: Cylinder Bore Size ? Johnson 3hp '52-'54 JW-10

I'm with JB on this.I just brought back to life a 1958 JW-14,basicly the same motor as yours.The best I could get was about 55 psi out out of her,but she runs sweet,and starts right up every time.Maybe you don't need to tear it apart,and rebore it.

 

[1_Pull_Wonda]

Re: Cylinder Bore Size ? Johnson 3hp '52-'54 JW-10

I FOUND THE SMOKING GUN !!!

The following website has a parts catalog for 1952-54 3hp Evinrude Lightwin ? Ducktwin. It lists a .020 oversize piston as part #277283. Also, the standard size piston part number is the same ?part #277166.

http://www.outboard-boat-motor-repair.com/Evinrude 3 HP Lightwin Outboard Boat Motor/Evinrude Johnson 3 HP 1952-1954 Owners Manual.htm

Someone wrote ?1952? on my parts list catalog. Printed in the lower right corner is ?2M?4-53-NSP-3293?. I think this may have been a parts catalog that came out in early 1953. They did not list the over sized piston in it. Maybe in later parts catalogs for the 1952-54 JW-10, the over sized piston is listed.

I wanted to upload the parts list for both engines but, my files are too big or the wrong type. Maybe I'll try again later.

 

[steelespike]

Re: Cylinder Bore Size ? Johnson 3hp '52-'54 JW-10

Have you confirmed it actually needs a rebuild?

 

[hello6894]

Re: Cylinder Bore Size ? Johnson 3hp '52-'54 JW-10

First time on here does anyone know where to get a piston, rings, and rod kit for a jw11 .20 over? Thanks

 

[JB]

Re: Cylinder Bore Size ? Johnson 3hp '52-'54 JW-10

Hello, hello.

Welcome to iboats.

"Hijacking" a thread is redirecting it to your question and away from the original poster. It is bad internet manners.

Please start a new thread.