New pistons?

kart74

kart74

New member
Joined
Jul 18, 2006
Messages
130
Age
42
Location
New Berlin, WI
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?
 
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
 
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.
 
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.
 
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.
 
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.
 
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.
 
piston.PNG 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.
 
thank you! As long as the cylinder looks good after cleaning it up i think ill be set. Thanks again for all the help!
 
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?
 
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