[chapu]

Subject: Evinrude Outboard 1993 175 Hp Serial No.175EXETG We have the above engine and want to buy Standard new Ring sets (part No. 433096) however 5 of the piston heads have one thick ring and one thin ring (one flat I think and one, the thin one, concave) these pistons are original - is this true or are they both flat? 1 piston head which was changed and has 2 thick rings (should they both be flat, one flat and the other concave?) and I dont know their number part... I would like to know if it is ok to have this apparently different piston head working with the other five, it looks the same size and weight etc., I really dont know where the changed piston came from? Did Evinrude change the ring configuration along the way and if so is it ok to use the two thick rings piston with the other five?

[Dhadley]

By "piston head" we think you mean piston. Clean the top of the pistons carefully until you can see if there are any numbers on them. Also look inside the piston and see if there is anything on the wrist pin boss area.It does indeed sound as if you have 5 OE and 1 aftermarket piston. No problem at all, we just need the numbers to get you the right part numbers for rings.Let us know!

[chapu]

Thanks for your help.The pistons are numbered as follows:434503 (3 pistons)434504 (2 pistons)436243 (1 piston)These are the first six numbers in a series.Can I mix the 436243 with the others?

[Dhadley]

The 434503 and 434504 pistons and their rings (433096) were used from 1991 to 93. In 94 they went to a different ring package (436353) which was used on the piston 436243. They both do the same thing. Yes you can use that piston if the cylinder is in spec. I strongly suspect that once your machine shop measures it you will find its not and you will be boring it anyway.Good luck!