there where some old mikunis the other week on ebay that i went to look at in the car. they werent tuned real well, but made a noticeable topend increase in power. they were on a stock 1200. there are some keihin fcr pumper carbs on ebay at the moment. they are the most awesome carb ever!! so many adjustments, nust need to spend the time getting them right. helps if you know a motorcycle tuner.
http://www.ebay.com.au/itm/datsun-120 ... ories&hash=item23190b6887

Dave I do think the Keihin FCR carbs make more power based on a couple of things:

When both SCCA D-Sports Racers and GT-5 / Lites used A-series motors , the DSR A-series made more power. The major difference being the FCR carbs. Additionally SCCA has banned motorcycle carbs for GT-cars.

The claimed power outputs of Sunny race cars........anecdotal of course.

Most importantly the Keihin carbs flow more.


The webers do have an advantage in that there are loads of tuners who know them well and can get the most out of them. As a motorcycle racer first I was familiar with how they worked (my new Beta 520 Enduro uses the same carb). If you're familiar with SU's you'll understand the concept of needles, all the rest is pretty much the same. The biggest thing I'd recommend if you tune them yourself is an air fuel ratio meter..................attempting to differentiate between lean stutter and rich flutter by ear is a bit dodgey if you palyry with carbs much.

The Factory Pro site helped a lot, my biggest issue was with GX cam the pilot jet and needle needed to be a kinda fat, I ended up with 3 sets of needle getting it right. Then as soon as I went to the cam with 280 duration and .460 lift that same set up made the pilot jet 6 steps to rich but the main only went up three steps. I also leaned out the low speed air correction jet but the high speed air correction stayed the same....................know different the webers. The myth about the flat slides, that you can't just whack them open is really a case of tuning. You can know do that on my motor.................it's now goes rrrrrrrRRRRRRRRRWAAAAAAAA, instead of falling on it's face. The camshaft on the other hand is now happy if you try to pin it below 4K.

http://www.factorypro.com/tech/tech_t ... ocedures/tuning_FCR_Burns,Pat.html


Finally I'm working on the A15 and the 39mm carbs are much better suited to the bigger displacement then the A12.

Tom