1997 phazer burning hole in piston

srxtim26076

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Joined
Jan 24, 2005
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Age
66
My son has a 1997 phazer that overheated and burned a hole in the piston on the clutch side. We replaced the piston, cleaned up the cylinder, head gaskets,disconnected the oil pump and ran premix. put in all new fuel lines, went through the carbs.

We took it out again this weekend and the same cylinder overheated and made some backfiring, and choking sounds. WE dissasambled the entire engine and have purchased new main crankshaft seals. (the old seals dont look bad). I have noticed that the two center bearings have some shaffing marks on the outer diameter. Is this a problem?

SHould I use Yamabond on the outside of the bearings?
 

Hmmm....Interesting. I would do as Redsnake3 said, and check the fan belt. I would also make sure all the seals are good and make sure that you dont have any kind of pinholes in any fuel or oil lines. Ive seen 2-stroke watercraft engines get pinholes in an oil line and they will sieze over and over untill because air gets in through the oil.
I would also check once again and make sure that you dont have any kind of blockage in the carbs. Check the jets and while you are at it make sure it has the right jets in it.
Now, I just happened to glace at my PZ480 service manual and it states that the main jet is a #148.8. This seems somewhat strange to me, I always thought that the clutch side got a fatter jet because it runs hotter than the mag side does. However, I have limited experience with Yamahas, so Im not the best source for this. Well, if your Phazer is a PZ480, it is supposed to get #143.8 jets. It might not have the right jets in it. I would also check and make sure that there isnt anything blocking the airflow under the engine shroud. Perhaps there is some kind of a nest in there that is limiting the airflow.
Hebi
 


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