[SEL] Briggs & Stratton NP help needed

[Tony & Jackie]

Jerry,
Most of the N, W and 5 series engines used the same piston I believe.

Best source of parts for small engines is John Smith at www.smithservice.org

C-ya...
Tony Kimmell


At 12:15 PM 8/1/2007, you wrote:
>   Hi All,
>          I'm rebuilding a 1946 Briggs & Stratton NP powered Pioneer
>Gen-E-Motor 12 volt genset (battery charger or whatever).
>
>          It's running but the bore is shot, the piston is shot, the gudgeon
>pin is shot and the rings are shot !!!
>
>          Actually the previous butcher who worked on this engine must have
>broken the oil ring - the oil ring gap was filled with "ring spacers"  and
>the other rings had gaps of about 3 to 4 millimetres !!. The generator
>still works and puts out the right voltage (15 volts I think).
>
>          The piston is aluminium and flat topped.
>
>          Can anyone point me in the right direction for spares. I've
>written to Briggs but their answer was unhelpful to say the least!
>
>          My choices are:
>
>          First prize)  Find a good (preferably new) oversized piston with
>conrod and gudgeon pin and rebore the block. (I can have rings made locally).
>
>          Second prize) Find a new standard piston et al and 
> resleeve the block.
>
>          Third prize) Find a piston from another make of engine with
>similar dimensions and either rebore or resleeve to make it work.
>
>          Fourth prize) Resleeve the block and machine the existing piston
>and have bigger rings made to fit (again, I can have rings made locally)
>but this would be a last resort as the existing piston's ring lans have
>worn unevenly on the diameter and I do not know if there is enough "meat"
>left for this kind of treatment.
>
>          Fifth prize) Find a "piston blank" that fits the measurements and
>machine that. Hepolite used to make these but I cannot find them locally
>any more.
>
>          I do not have the knowledge or expertise to have a new piston cast.
>
>          The engine is a 2" Bore X 2" Stroke and the dimensions of the
>existing piston are as follows: Apologies for the metric measurements.
>
>          Diameter: 50.6mm
>          Height:  53.89mm
>          Gudgeon Pin diameter : 12.4mm ( I would have thought 1/2" or
>12.7mm but thats what my Mitutoyo digital vernier says).
>          Height from centre of gudgeon pin to top of piston = 32mm
>
>          For what it's worth the engine specs are as follows:
>          Model: NP
>          Type No.: 306534
>          Serial No.: 695366
>          Manufactured August 1947
>
>          If anyone from this great storehouse of information can help I
>will be eternally in your debt.
>
>Keep the revs up (or down)
>Jerry Evans
>Near Johannesburg in Sunny South Africa.
>Tel. (016) 365-5787
>Intntl.: +2716 365-5787
>Cell: 083 293 7191
>Visit our website for old engines in South Africa.
>www.oldengine.org/members/evans