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IS 64.80 Acceptable bore for a set of 64.75 pistons?


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I just put a new set of Wisecos in my bike and was looking at the instruction sheet thats included with the piston kit and I read the same damn "drill two holes" line. I was like... "fuck that shit, I ain't drillin my shiny new pistons".

 

What is this about? Any body have a clue?

 

Yah, Ragun, sorry bout that, gotta get used to the new forum.

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What is this about? Any body have a clue?

 

 

 

"Lubrication holes (2-cycle engines)

If the cylinder has an exhaust bridge, the piston should contain lubrication holes on the skirt

where it contacts the exhaust bridge. If the piston does not have the lubrication holes on the

skirt, follow these steps to drill the lubrication holes.

1. Install the piston and wrist pin on the connecting rod using one circlip.

2. Slide the cylinder over the piston and align it to its normal position on the crankcase.

3. Slowly turn the engine over until the bottom ring groove is at the top of the exhaust

bridge.

4. Reach through the exhaust port with a pencil, and mark a

vertical line on the piston on both sides of the exhaust skirt.

5. Remove the cylinder and piston, and drill 2 holes (.060 - .090

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"Lubrication holes (2-cycle engines)

If the cylinder has an exhaust bridge, the piston should contain lubrication holes on the skirt

where it contacts the exhaust bridge. If the piston does not have the lubrication holes on the

skirt, follow these steps to drill the lubrication holes.

1. Install the piston and wrist pin on the connecting rod using one circlip.

2. Slide the cylinder over the piston and align it to its normal position on the crankcase.

3. Slowly turn the engine over until the bottom ring groove is at the top of the exhaust

bridge.

4. Reach through the exhaust port with a pencil, and mark a

vertical line on the piston on both sides of the exhaust skirt.

5. Remove the cylinder and piston, and drill 2 holes (.060 - .090

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Yes, i saw that, im the one who posted the link. What is an exhaust bridge? Do banshees need this or not? It the first time ive heard of this.

 

There's no exhaust bridge in a Banshee cylinder, so the piston drillin is not necessary.

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I went thru the same thing, wondering about drilling the holes on the exhaust side of the piston, when I rebuilt the 1985 250r motor I had.

Come to find out that the earlier 250r 3 wheeler motors "85" - "86" didn't have the exhaust bridge, I think they started that in 1987.

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