Has this motor been rebuilt?

[Robert Harris]

I am getting ready to rebuild powerhead on a Johnson 115 V4 (1980).Is there a way to easily tell if it has been worked on before such as boring or new pistons.I am new to outboards mostly auto experience.I just don't want to tear it all down to find out it has already been bored to max.<br />One more thing , why did they put such a large nut on the flywheel? What is that, a 1 5/16 inch or something? Those are usually 3/4 inh drive, right? I guess I'll have to borrow one somewhere.<br /><br />Thanks for the time.

 

[ob]

Re: Has this motor been rebuilt?

RH,Close inspection of fasteners should reveal whether motor has been into before.Check to see if paint on head covers and case looks virgin or simply remove one of the head covers and mich the bore.

 

[93bronco]

Re: Has this motor been rebuilt?

yea i would pull both heads, they have to come off any way. is there a specific reason for the rebuild?

 

[Walker]

Re: Has this motor been rebuilt?

If it's been bore the pistons should be marked .010, .020, or .030.

 

[Robert Harris]

Re: Has this motor been rebuilt?

Thanks for the response. The reason for the rebuild is piston meltdown causing damage to cylinder and head.<br /><br />I bought this boat and motor for a winter project.It just seems for a 23 year old motor that the nuts and bolts are coming off pretty easy.It appeared that the head bolts were missing some paint.<br /><br />I didn't know if I could take a measurement on the cylinder to know for sure.I have not been able to get it apart yet and check the crank, which if that is bad the motor is junk anyways.Trying to find a buddy with a 3/4 inch drive set to get that flywheel off.

 

[ICEMAN]

Re: Has this motor been rebuilt?

The socket you are looking for is available in a 1/2 inch drive. Just try to get a standard type socket, not an impact socket. Impact sockets are usually thicker walled and may not fit in the hole around the nut, if the nut is recessed. Some replacement oversize pistons do not have a marking on the top of the piston with the oversize. You can measure the cylinder bore to check also.

 

[Robert Harris]

Re: Has this motor been rebuilt?

Where can I find stock cylider bore size for that 1980 Johnson 115 V4. Do I need a special tool to measure or will a tape measure give me close enough to tell.<br /><br />Thanks

 

[wilde1j]

Re: Has this motor been rebuilt?

You need an inside (bore) micrometer to measure the bore. You need a shop manual for the std bore diameter. You need something to measure to +/- 0.001", so you can forget the tape.

 

[ob]

Re: Has this motor been rebuilt?

RH, According to my sources the standard bore for a 115 johnson is 3.500.As mentioned above you'll need a precision tool to determine from measurement.Inside michs are calibrated with outside michs which are calibrated with standards.There are a number of tools to transfer reading from bore to outside michrometer.The simplest being a telescoping guage.If any oversizing is necessary the machinist can make the determination of actual bore size to which oversize piston.