newbie performance help

[willyoungphoto]

I'm hoping someone can point me in the right direction. I am building a 1963 BMW 700CS (I realize this is not a motorcycle and hopefully not blasphemy on this forum). These came with a variation of the engine used in the R67's if i'm not mistaken. Instead of the 28hp, the 700CS increased bore to 78mm and compression to 9.0:1 as well as using a twin carb design to bring it up to 40hp. While cleaning out a garage I came across what would be equivalent of about four of these boxer engines (two twin-carb, two single-carb) and have decided I would like to try to get some more power out of this engine since I have parts to pick from. Has anyone done any performance modifications to their air cooled boxers? What i'm looking at/considering/wondering about is: best carb setup for the twin carb design, headwork (are there larger valves and better springs available?), has anyone bored out the cylinders and if so where might I be able to find larger/upgraded pistons? Any information to do with any of this, even a point in the right direction, would be very helpful. I have had quite a bit of experience with this engine, as well as BMW's 297cc one cylinder, however only in stock forms. I live about 6,000 feet above sea level so any extra power I can get would be great.

[Duane Ausherman]

If you increase the hp of those engines you nearly always lose reliability. They were not reliable in the first place, as in daily use, they didn't last very long at all.

These are collector items, not daily drivers. They are too expensive for most of us to drive daily.

You might be able to find performance increases in hobby magazines of the day from Germany. The Germans hopped up everything.

[willyoungphoto]

Thanks, I'll see if I can dig any old publications up. I definitely won't be using this 700 as a daily driver, it is just going to be a Sunday/car show driver.

[Deleted User 62]

There is a German language book called "1000 Tricks fur Schnelle BMWs" that might have some information. Copies show up on German eBay occasionally. ISBN 3-87943-226-0