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

JS Motorsport Products

Norton lightweight pistons weigh 1/3 less than stock items, Kit includes rings, clips and .708" DLC coated pins for 750, 850, 920 and 1007cc motors. Smoothing out the vibes and reducing stress on the motor is the best thing you can do for your Norton. Street bikes are more pleasant to ride and racers have a new advantage. A drop in kit with no modifications except that Hi C.R. motors with bores greater than 78.5mm will need larger diameter combustion chambers. These must be combined with our longer rods. (more info).

Price: $435 set

Select Bore:


Norton Ultra Hi compression domed piston kit for racing fuel only. These slightly domed pistons to give you approx 11.3:1 C.R. for 750 long strokes and 750 shortstrokes (more info). A drop in kit with no modifications except that bores greater than 78.5mm will need larger diameter combustion chambers. Includes rings & .708" DLC pins. Same light weight as our flat top pistons. These must be combined with our longer rods. Not recommended for 850s and up unless using alcohol (approx 12.5 to 13:1 C.R.). Will work for 850s with combustion chambers larger than 51cc (approx 12:1 C.R.).

Price: $535 set

Select Bore:

Top quality 6.4" Carrillo Norton rods. There is nothing stronger available for our Nortons. Special lightweight, low vibration design has longer length and bushless wristpin while retaining standard 89mm stroke. Because of their longer length, they must be paired with our lightweight pistons, and must use .708" DLC coated pins in the bushless small ends (the complete kit drops right in and uses regular shell bearings). Choose special short stroke 6.57" length rods for 80.4mm stroke racing cranks (more info).

Price: $690 set

Select stroke:

Special order ultralightweight 6.4" Carrillo rods (saves 10 grams on each small end). For Atlas and solid framed 750s up to 80 HP and 500 to 650cc Dominators. Adds $100 to regular price. Special order lightweight pistons available for 500 to 650 Dominator twins. Contact us for details.

Totalseal type gapless 2nd overlapping rings for perfect compression and sealing. This upgrade will convert your regular rings to gapless when you order pistons. Or you can add this upgrade to the ring set item below to convert them to gapless. Expect a little more kickstart pressure. (see demo video).

Price: $50 per set

Replacement regular style piston ring sets for JS lightweight pistons. If you want them to be gapless then add the upgrade item above.

Price: $50 set

Select size:

High strength .708" DLC pins (diamond like coating) - the same as come with our lightweight pistons. Will not fit stock pistons or rods

Price: $150 set

Four wire wrist pin clips for our lightweight pistons.

Price: $6 set

Unbeatable deal for 32mm or 34mm Flat slide Twin PWK Carb Kit. Jetted and tuned for Nortons with special JS needles designed "in house". Comes with lower cables, curved manifolds, heavy duty rubber boots and clamps, special T handle mix screw. Many special JS upgrades not available elsewhere, No modifications necessary (more info). Choose aircleaner below. Customers with 30mm port heads or those buying 34mm carbs see sleeved/tapered manifolds below. 34mm carbs need the twist grip, cable & junction box below because the original parts do not have enough travel. See twist grip and plumbing kit below.

Price: $435 set

Select carb

Cam being used:

Hi flow pancake K&N airfilter for dual flatslide carbs on Commandos (flow rate 193 CFM per carb). Fits within the original airbox backing plate. One filter fits two carbs. (installed photo).

Price: $60

Modify curved intake manifolds to fit heads with 30mm ports (also acceptable for 28.5mm ports). A short machined/tapered/conical 30mm I.D. sleeve is pressed into the head side of the manifold - the carb side remains at 32mm. 34mm manifolds are tapered down to 32mm, This is only an addition to the above carb kit and must accompany a carb kit order because the manifolds are not sold separately.

Price: $65
must also order carb kit

Select size:

Improved action twistgrip, upper cable & junction box for 32 or 34mm PWK/Keihin carbs as above. No switches. Necessary for 34mm carbs because the original parts do not have enough travel. Cable for 34mm carbs with MK3 twist grip available (contact us for info).

Price: $45


Select carb

Plumbing and filter kit for twin or single carb kits. High quality Tygon thick walled tubing to prevent kinks. Filter can be cleaned & lasts indefinitely. A time saving clean & simple layout that's easy to install. Single carb plumbing kit is similar but not shown in photo. Petcock barbs not included (use your originals) (installed photo).

Price: $55


Select carb

Two main jets , two idle jets or two needle jets for twin carbs as above. Choose size. See tuning instructions. (carb tuning).

Price: $10 for two jets


Select size:

Two custom needles designed in house specifically for Nortons with 32 or 34mm PWK/Keihin design carbs.

Price: $10 set

Two extra bowl gaskets for flatlside carbs. So you don't have to wait for them to shrink back down (when re-installing) if your gaskets temporarily swell up from alcohol in today’s gas.

Price: $10 set

Heavy duty thick wall rubber boots for flatside carbs. Clips included.

Price: $45

32mm intake manifolds with balance tubes. Fits JS flatslides, Amal Mk2 and any carb with a 40mm spigot. Fits rubber boots above.

Price: $50

Complete Radius Cam Kit - including our custom Radius cam, set of lightweight lifters, bronze lifter blocks, set of stronger, lighter, shorter pushrods to eliminate flexing (more info). For stage 3 cams the lifters are specially ground to 7/8" radius. Contact us to special order Atlas cams or cams for 90 degree cranks.

Price: $895 set

Choose cam:

Choose cylinder head for correct pushrods:

Norton radius cam for use with our lightweight radiused lifters and blocks. Will not work with stock lifters. Four cam grinds available (more info). Contact us to special order Atlas cams.

Price: $395

Choose cam:

JS Motorsport Bronze lifter blocks for lightweight radiused lifters - a huge improvement over heavy stock lifters. Use with our long lasting, custom-grind radiused camshaft.

Price: $160

Norton pushrods to be used with our lightweight radiused lifters and radiused cam only. Will not fit stock lifters. Made of high strength aircraft alloy. Virtually eliminates flexing.

Price: $150 set

Select head for correct pushrod length:

Stock size valve & beehive spring kit for street or racing. Out-performs all others because the springs are approx 1/2 the weight and that raises your RPM limit and takes stress & heat off your motor. Cam flex is reduced and saved HP goes to the rear wheel. The conical shape eliminates the need for an inner spring and allows for a smaller lighter retainer - a smarter design than dual springs. This is a complete drop in kit - everything fits. Custom black diamond valves (eliminates stem wear) with hard stellite tips, beehive springs, titanium spring retainers, spring seats and spring balancing shims. Contact us to special order big valves (more info).

Price: $375 set

Select street or racing for correct spring seat

Beehive valve springs without the valves. You must modify your valve tips to fit (see diagram). Titanium retainers, spring seats and balancing shims included.

Price: $200

Select street or racing for correct spring seat

Black diamond stock size valve set with stem tips specially machined for Beehive valve springs only. Contact us to special order big valves.

Price: $175 set

Special short lash caps to fit valve tips for Beehive springs. For those who modify their own valves. Also fits stock valves (not necessary for our Black diamond valves).

Price: $12 set

Our custom Copper Head Gasket for Norton twins. In various thicknesses to alter compression. 3/32" and 1/8" gaskets available on special order (double the cost) (more info).

Price: $35
Select gasket:  

Our custom Copper Base gasket for Norton Twins. .021" thick (more info).

Price: $30
Select motor:  

Slippery Turcite fork bushings for Norton forks. Reduce friction, sticktion, fork tube wear and get a smoother ride with this excellent long lasting material. Expansion slit ensures a precise fit. Includes uppers & lowers. A drop in kit. See alum sleeves below.

Price: $165 set

Get rid of the annoying metallic "clunking" in your forks with these aluminum sleeves. They give you a hydraulic bump stop at the top and bottom limits of fork travel as they should have been designed in the first place. Special slit in the upper collar insures a perfect tight fit. Special 1/8" oil hole plugs make these work when others don't (more info).

Price: $55 set

Norton Monoshock Racing Chassis plans (twin shock option included).
Build your own Battle Of The Twins class winning chassis.
Complete details on tubing, geometry, and implementation (more info).

Price: $10.00

One piece aluminum rocker spindle covers, including button head allen screws and aluminum washers.

Price: $45 set

A must for every Norton racer - Novice or expert. This manual contains priceless info gleaned from some of the greatest tuners of our time including notes from Peter Williams, Ron Wood, C.R. Axtell, Leo Goff and many others. Subject material includes crankshaft lightening, reshaping and balancing (how to balance your own crank). Strengthening of crank PTO shaft (very important). Detailed porting specs for three stages of tune. Exhaust pipe and megaphone specs. Making and fitting your own big valves (1mm oversize). Racing cam specs for Norton factory cams, Axtell cams and other high performance cams. Piston and pin lightening. Handling/suspension improvements for Norton forks. Photos of rear monoshock layouts (racing frame) and much more. Order now and make your bike a winner.

Price: $25

Unbeatable price for Joe Hunt magneto with high powered rare earth magnets for easy one kick starting. Hotter spark and more reliable than electronic ignition systems. Miles ahead of the troublesome Lucas mags. For mounting behind cylinders (Atlas style). JS improvements include upgraded fasteners, re-usable silicone mounting gasket, detailed installation instructions with photos, Most importantly the cam is provide with an allen hex that enables easy timing, making this a better value than from other suppliers (demo video).
(more info & photos).

Price: $695

Unbeatable price for Joe Hunt magneto with high powered rare earth magnets for easy one kick starting. Hotter spark, easier starting and more reliable than electronic ignition systems. Same as above but for mounting on timing cover (Commando style). Special adapter plate included. JS improvements include upgraded fasteners, detailed installation instructions & timing tool (demo video).
(installed photo).
(how to mount magneto behind Commando cylinders).

Price: $795

Quick action Amal style twist grip.

Price: $15

TERMS: 30 day exchange limit upon pre-approval; 15% restocking fee. Returned parts must be in original condition. Items are non-returnable once they have been installed.