Vintage Dirt Bike Q & A

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 Post subject: 'YZ465G bore wear.
PostPosted: Thu Oct 20, 2005 8:35 pm 
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Joined: Thu Oct 20, 2005 8:14 pm
Posts: 66
Hi,
I am racing two '80 model YZ465G's and both are suffering severe bore wear at bottom of cylinder on intake side.

The wear mark corresponds to the cut out in the piston.
I was wondering if this was caused by a lack of skirt support due to the intake cut away.

Both pistons are Wisecos.........fuel oil mix is 32:1 Yama R

Thanks


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 Post subject: YZ465 bore wear
PostPosted: Fri Dec 09, 2005 10:28 am 
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Joined: Wed May 18, 2005 10:55 am
Posts: 50
Location: College Park, MD
The type of bore wear you describe is not uncommon in those big bore Yamahas. Most wear is caused by DIRT coming thru the air filter. The Yamalube at 32:1 should have provided enough lubrication to prevent piston contact with the cylinder except when they ping under load. Using 100oct. fuel mix helps there to reduce pinging.

Also, early Wiseco pistons were notorious for wearing out fast, and also creating bore wear in the process. Their new stuff is much better, but I still prefer to use oem or oem style if it's available in the size I need.

OriginalDirt

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