1991 KDX200 exh bridge

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liverup
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1991 KDX200 exh bridge

Post by liverup »

I’m putting a Wiseco piston in my 91 KX 200. The Wiseco instructions are telling me if it has an exhaust bridge to make some marks below the bottom ring where that exhaust bridge is supposed to be. Mine does not have a bridge in the main exhaust port. Everything I’m seeing says it should have an exhaust bridge. Any thoughts?
SpruceItUp
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Re: 1991 KDX200 exh bridge

Post by SpruceItUp »

I'm not entirely sure what you mean by making marks below the bottom ring. Do you mean drill holes for lubrication?
These bikes have 2 exhaust bridges, which are between the main exhaust outlet and where the subvalves are. The last Wiseco piston I got for my 92 200 already had 2 holes drilled for both of the bridges, likely because it'd be a pain in the butt to measure out where they need to go exactly because the bridges are offset unlike a lot of 2 stroke cylinders (at least 90's+ MX cylinders) where the exhaust bridge splits the main exhaust outlet straight down the middle, likely because there are no subvalves, unlike the KDX.
(Or I'm just slow and it would just pain for me to figure out where the holes go, but we all have our downfalls :) )

Does your piston already have 2 holes on each side of the arrow on the piston? Those holes should line up with the exhaust bridges in the cylinder. I'm sure you already know but that arrow points towards the exhaust side of the cylinder. Make sure it goes that way when you put it together, or bad things await.
liverup
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Re: 1991 KDX200 exh bridge

Post by liverup »

Ok that makes sense. I was expecting a bridge dividing the center exhaust port. Yes my new Wiseco piston does have the lubrication holes. The instructions showed drawing a pencil line on each side of the bridge and then removing the piston and drilling holes in between the pencil lines below the bottom ring.
I should be good to go. Thank you for clarifying that for me.
SpruceItUp
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Re: 1991 KDX200 exh bridge

Post by SpruceItUp »

Glad you got it figured out. Have fun riding!
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