Yz85 Rebuild

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Blink-182

Member

Feb 2, 2008

127

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• May 31, 2008

• #1

So im rebuilding my yz85 right now and i was wondering how to tell if it was a weicso piston in it? i know its not the stocker because it doesnt say the size with the A or anything and on the top of this one the last number is an A so does this mean i should go ahead and get an A sized im guessing STD sized piston? also i noticed its missing the dowl pins so im going to go ahead and get those from bike bandit and i just bought some brown & sharpe digital calipers so im wondering how to use all of this thanks also what would happen from not running with dowl pins? this is my first top end rebuild

 

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Blink-182

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Feb 2, 2008

127

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• Jun 1, 2008

• Thread starter
• #2

ok i looked into my cylinder and i dont think this is good is thing going to need a hone or replate or something? my camera isnt obviously great quailty but you can see sort of the silver marks is this bad?

 

C

CRazy250

Member

May 28, 2006

334

1

• Jun 1, 2008

• #3

if you can feel any scratches with your fingernail you should hone or re plate.

 

V

VISaki

Member

May 25, 2008

45

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• Jun 1, 2008

• #4

Naw thats normal you'll always see a f;ow of lines from where the piston was traveling..main thing is when you install it back in there make sure that you run at least a rich mix for the first tank full just to lubricate the new piston and so its seats better in the cylinder..usually with two ring pistons you won't have as many scratch's. change your coolant aswell when you do a rebuild so you have fresh new coolant for that fresh new piston aswell as tranny oil. Make it a habit of doing this and your bike will last a long time.

 

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Blink-182

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Feb 2, 2008

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• Jun 1, 2008

• Thread starter
• #5

oh alright but what i was worryed about is this normal or is this scuffing left on the cylinder left from the piston?, in this picture i try'd to make it best as possible with this camera but on top do you see the discoloration? where it goes a copper looking color to silver? is this from the piston and does it matter or is this plating comeing off?

 

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Blink-182

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Feb 2, 2008

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• Jun 1, 2008

• Thread starter
• #6

VISaki said:

Naw thats normal you'll always see a f;ow of lines from where the piston was traveling..main thing is when you install it back in there make sure that you run at least a rich mix for the first tank full just to lubricate the new piston and so its seats better in the cylinder..usually with two ring pistons you won't have as many scratch's. change your coolant aswell when you do a rebuild so you have fresh new coolant for that fresh new piston aswell as tranny oil. Make it a habit of doing this and your bike will last a long time.

Click to expand...

ive heard about that adding more oil but id rather not because that actually makes it leaner

 

Patman

Pantless Wonder

LIFETIME SPONSOR

Dec 26, 1999

19,765

1

• Jun 2, 2008

• #7

Adjust your jetting properly and you can easily run 24:1 or even 16:1 with no problem, minimal if any smoke and longer life.

 

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Blink-182

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Feb 2, 2008

127

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• Jun 2, 2008

• Thread starter
• #8

thanks guys i serously thought i needed a replate but should i get the same piston size? on the top if it it says 2975A im pretty sure its a weisco but should i get the same A size? and is that what a std standerd size piston is?

 

J

_JOE_

~SPONSOR~

May 10, 2007

4,697

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• Jun 2, 2008

• #9

As far as I know if you go with Wiseco you only have one std bore size. That discoloration at the top of the cylinder is above the portion in which the piston travels. That is actually part of the combustion chamber. Use a scotch brite pad to scrub it up a bit and you should be fine.

 

B

Blink-182

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Feb 2, 2008

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• Jun 3, 2008

• Thread starter
• #10

so i should order a A piston? oh and if the dowl pins fell into the crank would you feel them in there when u moved the rod? im pretty sure they wherent even on there in the first place but i was so excited taking it off that i dont remember if they could have ?

 

H

helio lucas

~SPONSOR~

Jun 20, 2007

1,020

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• Jun 3, 2008

• #11

try with a magnet...