piston pin (gudgeon or wrist pin)

please replace this part if you measure wear on it compared to the unworn shoulders (17.00mm) should be a difference <0.05mm (.002"), or the bearing surface is stained black (salt corrosion) or pitted or ridged. if you run your fingernail over the surface in the centre and its anything but smooth, replace it

This affects the highest stressed and hottest component in the entire engine that also has salt air (bearing around it) so should be perfect.

reason this corrodes is always the same : NOT oiling/winterising like the manual directs  when not in use for winter months, particularly in salt-air environment, then the bearing needles rust and slowly dissolve 'lines' into the adjacent pin surface. 

This part sometimes corrode due to saltwater flooding and forgetting to winterise as instructed in the manual. if the rollers or cage is corroded, particularly pitted, then it is important to refit new also.

engine numbers >22000 (will have steel connecting rod 52284/1 and a roller bearing around this pin top to allow 2% oil, earlier engines and all vire 6 engines had an alloy rod with bronze bush around this same pin, instead requiring 3% oil)

please also inspect for wear:

• 52284/1 roller bearing or bronze bush on earlier engines <22000
• 52008 crank pin. 52293/6 rod bearing (check play, noise and edges visible if not dissassembling)
• 52073 main ball bearing, should be smooth turned by hand no vibration.

Note. I do offer a specialist crankshaft rebuild service if you want to make sure your crank pin and bottom bearing 52293/6 are ok, please email me your concerns for a quotation.

also i offer rebuilt engine on exchange; short engine without piston or cylinder, full engine, also with gearbox and pump, also with silencer, also with carburettor and dynastart. if you cannot find these items in stock on the site, email me for a quotation.