250R greenhorn needs help with a build

[wannaride]

Hello,
I'm new to the forum and I must say that it seems very cool. I have been living and breathing powersports for 25+ years. Recently I decided to build a 250R trike. I do not have any experience building these machines. My goal is to build a scary fast bike for trail riding. I was looking into aftermarket cylinders and noticed they only go back to 1986. Looking at the used bikes in my area....there are tons of 85s..and the 86s seem rare.
Do I need to start with an 86 motor for something like an ESR cylinder?
Can the case on a 85 motor be machined to work with the aftermarket cylinders?
Basically...whats the main difference between the 85 and 86?
thanks for any help!!

[falloutboy]

Don't hold me to this, but, as far as the cylinder goes, I THINK the two years were just ported differently.

[bkm]

You can use the ESR cylinder on the '85 lower end as long as the piston is set up for the short rod of the 85/86. 85's and 86's are essentially the same engines. There are differences but nothing to really get into.