BrotherJohn
New member
I have an '86 Evinrude 70 (Model BE70TLCDC) with almost the same story as @OldBoatOldNewbie in another thread. Don't know the full history of my engine but I've had it now for three years and it has been really reliable and has given a good ride with at least somehow decent mpg. Considering the age of it I was already more or less expecting that something may happen. And something really happened.
Running WOT the middle piston was maybe running lean and overheated which resulted a broken piston and some damage to the cylinder surface. Visually the head, pistons and cylinders look exactly as the pictures on the original post, a piece missing from the middle cylinder and there are scratches on that cylinder surface. Other cylinders and pistons are quite ok but I still consider getting all the cylinders bored to oversize (.030 o/s seems to be the usual way but I'll let the machine shop tell then what they think).
I dismantled the engine and I'm doing a quite complete overhaul of the engine in belief that it will serve me for many many years to come.
First a question related to oversizing: When the engine is bored to .030 oversize, will it result in need to change something to the engine? Larger jets to the carburetors, new carburetors, anything?
Many of the well equipped marine parts shops are located in the U.S. and they don't seem to ship to Finland where I happen to live. At least not in a budget friendly way. This gives me only a few options for getting new .030 pistons and that's where I'm now a bit stucked.
The original piston is number 394461
I was offered a "piston kit Johnson/Evinrude 50-70 hp 0.030 oversize" which looks right in the picture and the product details are as follows:
RecMar REC 5006702 Johnson/Evinrude 70 hp - 1986-94
Size: 3.1875" = 80.9625mm
+ 0.030" oversize (add-on is 0.762mm)
Height: 66,14mm
Replaces following manufacturer's part nr
- Johnson/Evinrude/OMC: 0398483, 0435351, 0437410, 0437412, 0778352, 5006702
- Sierra: SIE18-4064
- Mallory Marine: MAL9-53434
- GLM: GLM23790
The biggest question: Are these be the correct ones since my original piston nr is not referenced there?
Best regards and thanks in advance
-Jouni
Running WOT the middle piston was maybe running lean and overheated which resulted a broken piston and some damage to the cylinder surface. Visually the head, pistons and cylinders look exactly as the pictures on the original post, a piece missing from the middle cylinder and there are scratches on that cylinder surface. Other cylinders and pistons are quite ok but I still consider getting all the cylinders bored to oversize (.030 o/s seems to be the usual way but I'll let the machine shop tell then what they think).
I dismantled the engine and I'm doing a quite complete overhaul of the engine in belief that it will serve me for many many years to come.
First a question related to oversizing: When the engine is bored to .030 oversize, will it result in need to change something to the engine? Larger jets to the carburetors, new carburetors, anything?
Many of the well equipped marine parts shops are located in the U.S. and they don't seem to ship to Finland where I happen to live. At least not in a budget friendly way. This gives me only a few options for getting new .030 pistons and that's where I'm now a bit stucked.
The original piston is number 394461
I was offered a "piston kit Johnson/Evinrude 50-70 hp 0.030 oversize" which looks right in the picture and the product details are as follows:
RecMar REC 5006702 Johnson/Evinrude 70 hp - 1986-94
Size: 3.1875" = 80.9625mm
+ 0.030" oversize (add-on is 0.762mm)
Height: 66,14mm
Replaces following manufacturer's part nr
- Johnson/Evinrude/OMC: 0398483, 0435351, 0437410, 0437412, 0778352, 5006702
- Sierra: SIE18-4064
- Mallory Marine: MAL9-53434
- GLM: GLM23790
The biggest question: Are these be the correct ones since my original piston nr is not referenced there?
Best regards and thanks in advance
-Jouni
