660 Build update

[Painlessjoe]

Ok, thanks for the replies on my earlier post ,so I put new factory cyl piston kit in place of the am that failed which was refunded by the vendor I got it from .good business. And comparing the two you guys were spot on the am port openings where flat across top and bottom so I can see why the ring could ,would,did catch and break still going to try and get pics on here . Maybe I could have radiused them but I was wondering about changing the already changed timing. And the plating was bad also. Quick question. I have a 74 main jet in and the saw run very good but I’m only open 1/3 on the H side and still running rich .12000 . Go back to a smaller jet??

 

[DND 9000]

I answered your post already on Arboristside:

"I would try the smaller jet (.62mm) from the WJ-69 carb and tune it for start on the rich side, see what happens. The .74mm jet is from the WJ-76B used on the MS 660 Magnum in Brazil."