JS Motorsport
 
 
motorcycle
HIGH-PERFORMANCE
PARTS AND SERVICE
FOR NORTON TWINS
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. Smoothing out the vibes and reducing stress on the motor is the best thing you can do for your Norton. 750cc = 185 grams. 850cc = 207 grams, 920cc = 238 grams and 1007cc = 240 grams. 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:

Compression:

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 750cc long strokes and 750 shortstrokes (more info). 73mm = 185 grams. 77mm = 210 grams. 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. 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 more efficient 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). Small end = 106 grams. Big end = 326 grams. 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. Small end = 95 grams. Big end = 349 grams. 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. Ultralightweight flat top pistons available on special order. 73mm = approx 170 grams. 77mm = approx 185 grams. 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 (longer kickstart lever available from RGM).

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. 750cc pin = 51 grams, 850cc pin = 58 grams

Price: $150 set

Four wire wrist pin clips for our lightweight pistons.

Price: $6 set

Hi performance Keihin 35mm FCR flat slide Twin Carb Kit. Jetted and tuned for Nortons. Complete with twist grip, cables, special porous-free curved manifolds, idle balance tube, thick walled heavy duty rubber boots and clamps, pre-syncronized (carbs are linked). (see installed photo). Plumbing kit recomended (below). Choose aircleaner below.

Price: $1095 set

Support for PWK Flatslide carbs will continue for existing customers.

Plumbing and filter kit. High quality Tygon thick walled tubing to prevent kinks. Pingle filter can be cleaned & lasts indefinitely. A time saving clean & simple layout that's easy to install. Use your original petcock barbs.

Price: $55

Hi flow pancake K&N airfilter for dual Keihin carbs on Commandos. K&N part # RC 2370

Price: $55

Complete Radius Cam Kit - including our custom Radius cam, set of lightweight lifters (38 grams compared to stock 75 gram lifters), bronze lifter blocks, set of stronger, 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. Same weight as stock.

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 of dual springs 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:  

High compression .003" thin head gasket rings. Thin copper wire for eliminating oil leaks at pushrod tunnels and oil return hole makes this a reliable and trouble free setup. This is the easiest way to raise compression approximately one point (10%) (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). Frames and rolling chassis are available on special order.

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.