Nissan 25hp? on cylinder scoring found.

[Charlesjoker]

I made a previous post, but didn't see it. Please disregard if this is repeat. I pulled head yesterday on my 25c3 for possible blown head gasket and found this cylinder scoring on top cylinder. It was going down to the hole which I believe connected to exhaust port. Never seen that before in 2 stroke. The carbon spot in head went to the scoring area in the cylinder. Is this a ring grabbing? Compression was 140 top and around 150 bottom. Thanks

 

[pvanv]

Re: Nissan 25hp? on cylinder scoring found.

I am thinking that you somehow ingested some debris. Maybe a small piece of aluminum. The cylinder marking extends up above the ring contact area of the cylinder. Odd color, too. Can you try to clean it up with some crocus cloth and solvent, then see if there is any real measurable scoring?

 

[Sea Rider]

Re: Nissan 25hp? on cylinder scoring found.

You can file using metal sand paper, one number after the thinnest grain you can get. Just sand smoothly and evenly. Check with fingertip if wall surface has smooth out.

Happy Boating

 

[Charlesjoker]

Re: Nissan 25hp? on cylinder scoring found.

Just got home from work. I was able to take advantage of the 70+ temp today and I did just what both said before you suggested it. Lightly sanded in 45 degree angle across it real lightly. With just min or so both directions it was gone. I deduced it ingested something but soft. The plug was new, but who knows when this took place. Cleaned it, puts some lubriplate on cylinder walls and put the head on with new gasket/thermostat..I could never feel a ledge with finger nail-so just going to keep the Amsoil in it and run it..Thanks for the help both pvana and Sea Rider. Now to hope some ducks actually migrate down -with this temp, probably flew back north...Randy Haughton, La