New pistons?

[kart74]

Just pulled the jugs off the viper. PTO and center have minor scuffs on the piston, but mag looks pretty scuffed. So do I put new pistons in all or just the mag? If I do all of them I was thinking the spi just cause of the cost. Thoughts?

 

[kart74]

 

[kart74]

I just looked and one oem piston is 110. I can get the spi 3 piston kit for 170... so I guess the question is... do I need a new mag piston? If so I guess spi it is

 

[captnviper]

Cant see pics, I know you cane get the skirts recoated. I cant reacall what it is though. here it is http://swaintech.com/race-coatings/race-coating-descriptions/piston-skirts/ get a hold of them.

 

[kart74]

The pics dont show up if you click on them?

 

[Vincent]

Nope!!!

 

[kart74]

Ok i think i fix the pictures above! let me know. I keep going back and forth, but i think i may just get the one new OEM and be done with it. I dont think it is good to run it as is.

 

[MURDER YAMAHA]

I would replace them all with OEM for sure, not a big fan of non OEM in a Yamaha, as they can suffer from metals, expanding at different rates, causing the same problem you are seeing now.

 

[kart74]

the pto and center barely have a mark on them. Is there a reason to replace all of them?

 

[RXMax]

Just put the mag in and run it. Those scuffs are ok!

 

[MURDER YAMAHA]

Boy, I don't know about that, looks like there are more than "barley have a mark" to me.
If you can feel anything with your fingernail, I personally, wouldn't reuse them.
Same goes for the cylinders.

 

[roudyroy1]

you need new pistons. are those marks only on the intake side? looks like snow ingestion

 

[kart74]

the mag piston has marks you can feel. That one is getting replaced... i ordered a OEM piston. The other 2 have small marks, but are just polished looking. no scratching at all. Same thing with the cylinders. The mag side has aluminum build up that i am going to try to clean up. The other 2 look perfect. All marks are on the intake side. I did run this thing on the asphalt at one point, and know it got hot more than once.

 

[captnviper]

Muriatic acid, brush a little on and wait, keep adding till it gets brittle. If it is near a port use clay. Google or duck duck go, if you havent yet.

 

[roudyroy1]

From a yamaha manual for lightly scored pistons. (for a red head, but should work).

if it got hot i would think that you would see 4 corner scuffing, if its only on the intake side that typically happens due a lack of lubrication from water washing the oil film off.... but i could be wrong so don't quote me on it LOL.

 

[kart74]

thank you! As long as the cylinder looks good after cleaning it up i think ill be set. Thanks again for all the help!

 

[kart74]

The cylinders cleaned up pretty good! Now i am just waiting for the piston and head gasket to show up. While i wait is there anything else i can be doing? Is it worth polishing the exhaust port or anything like that?