Vintage Dirt Bike Q & A

Hey guys, got another question. I'm putting my cylinder on and have a new 2 over Wisco Piston for it. In the instructions that came with the piston it says to drill 2 lubrication holes in the piston for the exhaust bridge. So before I drill into my new shinny expensive piston I wanted to know what all you others using Wisco Pistons do. I believe the stock piston never had any holes for this purpose, so are they necessary?

Thanks,
Matt

If the method for the 1978-1979 CR250R applies, you only need do this if your exhaust port is bridged. Wiseco sells the same piston for both these engines, but you do not need holes for the 1978 (single port) but do need them for the 1979 (two exhaust ports). You need make sure the lubrication holes line up with the bridge and their purpose is to get more pre-mix to what will be the hottest part of the cylinder.

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Michael Stiles
1979 Honda CR250R Elsinore | 2006 Husqvarna SM510R | 2007 Service Honda CR500R-AF

Hey Matt,

I work on these bikes all day, YES you need to drill the oiling holes. The reason there's no holes in the stocker are that it is casted and the Wiseco’s are forged. If you need any help give me a call and I can walk you through it. It's really not that hard to do.

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Don Brooks
Vintage Elsinores
Ventura, CA.
http://www.elsinores.com