JS Motorsport
JS Motorsport
4480 North Academy Avenue
Sanger, CA 93657
Phone/Fax: 559 875 0659
Email: jim@jsmotorsport.com
JS Motorsport Technical
Keihin carbs

Good looks and high quality make Keihin CRS smoothbores the best choice for your Norton. They're called "smooth bores" because at wide open throttle the inside of the carb becomes a smooth round tube and thats the most efficient shape for making power. Legal for AHMRA Bears and F750 classic racing. At JS motorsport we make custom mounting hardware to adapt these great carbs to Nortons. Both carbs are mechanically linked together so they come pre-sychronsized with only one throttle cable. Tuning is a snap. Special custom length manifolds give necessary frame clearance (see manifolds below). Single easy access choke lever operates both carbs. (see Keihin carb demo).

Top view showing exclusive JS custom throttle wheel and cable mounting backet.

Mark Gunnings Commando above. William Zeri's Commando below.

Nicks 850

Special short intake manifolds are custom made to provide a proper fit.

The balance tube is ideally located between the carburetor bodies.

A short arm replaces the left side cover Dzus D ring to give clearance on some models.

Plug color with the jetting I've worked out for Nortons.

CRS smoothbore carbs fitted into a Featherbed frame

CRS 33mm smoothbore carbs fitted into a Seeley frame

Dave's Rickman sporting JS Keihin 33mm CRS smoothbore carbs