discussion: Oldskool carbs or Motorbikes Keihin?

[firehawk]

Before I bought the AE86, I had a KP62 Starlet with a 4K engine and I put on it a set of four Mikuni BDS37 CV-carbs off a Yamaha FZR1000 Genesis. I had a simple steel intake manifold and the carbs attached to it using four small pieces of heavy duty rubber hose and clamps. Compared to getting a pair of Dellorto DRLA36 downdrafts and a manifold for them, the bike carbs were about half the price. Couldn't find any suitable velocity stacks for them, though - the outer diameter was just too weird. I ended up just putting the filters directly onto the carbs with re-useable zip-ties.

Getting the correct jets and needles can be quite expensive and a tedious job, so one needs to be prepared for trying out different settings and testing the car in different conditions. In my case, the jetting was already quite good for a 1300cc engine revving up to 7500rpm, so I only needed to change the needle clip positions a bit, tweak the air screws to get a good stable idle and sync the throttles. Once these were done, the car ran quite nicely and no longer pushed out huge clouds of black smoke out of the exhaust. They did spray back some fuel mist on overrun but I believe this is due to the cam overlap I had (304 deg rally camshaft). Had some 30cm long flames shooting out of the carbs when I was adjusting the ignition timing and retarded it a bit too far.

Here's a few photos of the carbs and manifold;
http://paranoia.tuug.fi/gallery2/v/jh/album51/album66/

...test fitting them on the car;
http://paranoia.tuug.fi/gallery2/v/jh/album51/album68/

And the final result;
http://paranoia.tuug.fi/gallery2/v/jh/al...6.jpg.html
http://paranoia.tuug.fi/gallery2/v/jh/al...G.jpg.html