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 for 750cc, 850cc and 920cc motors (contact us for 1007cc 83mm pistons). 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. Drop in with no machining necessary 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 12:1 C.R. depending on displacemont (more info). A drop in kit without any machining except that bores greater than 78.5mm will need larger diameter combustion chambers. Ideal for 750 short strokes. Includes rings & .708" DLC pins. Same light weight as our flat top pistons. These must be combined with our longer rods. Not recommended for 920s & up unless using alcohol

Price: $555 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:

ULTRALIGHTWEIGHT RODS FOR ATLAS AND SOLID FRAMED 750s AVAILABLE ON SPECIAL ORDER - requires crank rebalancing - also for 500 to 650 dominators - contact us for details. Ultralight pistons also available.

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).

$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

32mm or 34mm flat slide Twin Carb Kit. Orginally designed by Keihin, now remanufactured, customized, jetted and tuned for Nortons with special JS needles designed "in house". Complete with lower cables, airfilters, curved manifolds. rubber mounts and clamps, Many special JS upgrades not available from others including drilled fuel passages and custom JS float needles. No modifications necessary (more info). Customers with 30mm port heads or those buying 34mm carbs will need sleeved/tapered manifolds - next item below. 34mm carbs will need the twist grip, cable & junction box below because the original parts do not have enough travel. See alternative aircleaners and plumbing kits below.

Price: $495 set

Select carb

Cam being used:

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.

Price: $65

 


Select carb

Plumbing and filter kit for our flatslide 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: $69

 


Select carb

34mm single flatlside carb for those who like simplicity, economy & easy maintenance. Design by Keihin. Complete with cable, twist grip, airfilter, 2 into 1 manifold, rubber mount and clamps, Customized, jetted & tuned for Nortons with special needles and highly modified "in house" to meet thirsty single carb fuel demands at WOT. No modifications necessary other than removing airbox. See plumbing kit above. See alternative aircleaner below. (installed photo).

Price: $395

 


Select motor

Two main jets , two idle jets or two needle jets for twin carbs as above. Choose size. (.100" is our standard needle jet). See tuning instructions. (carb tuning).

$12 for two jets

 


Select size:

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

Price: $12 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: $8 set

Standard airfilter for flatside carbs (flow rate 180 CFM). Need two for dual carbs. Shortened custom length and narrow clamp for Commandos to fit within original airbox backing plate. Reinforced with alcohol resistant glue.

Price: $10
for one

Hi flow airfilter for flatslide carbs (flow rate 195 CFM). For Commandos (need two for dual carbs). Must remove original airbox backing plate for these to fit. Order these filters with a carb kit and you will be upgraded to the higher flow aircleaners.

Price: $25
for one

Hi flow K&N airfilter for dual flatslide carbs on Commandos (flow rate 193 CFM per carb). Fits within the original airbox backing plate. Order this filter separate or with a carb kit and you will be upgraded to the higher flow aircleaner.

Price: $50
for one

Two heavy duty thick wall rubber boots for flatside carbs. Clips included.

Price: $40
pair

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 must be ground to 7/8" radius. We provide this service (see below). Contact us to special order Atlas cams or cams for 90 degree cranks.

Price: $895 set

Choose cam:

Choose cylinder head for correct pushrods:

Labor charge to radius lifters to 7/8" - for stage 3 cams only. You must buy a JS 3 cam kit for this service.

Price: $85
labor only

Norton radius cam for use with our "tested" 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: $125 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. Black diamond valves (eliminates stem wear) with hard stellite tips, beehive springs, titanium spring retainers, spring cups and spring spacers. For complete big valve kit see next item below (more info).

Price: $445 set

Select street or racing for correct washers:

Big valve beehive spring kit for street or racing. Requires re-angled valve guides. 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. All oversize valves are stainless steel without black coating. Induction hardened stem tips, beehive springs, titanium spring retainers, spring cups and spring spacers (more info).

Price: $625 set

Select street or racing for correct washers:

Choose size:

Beehive valve springs without the valves. You must modify your valve tips to fit (see diagram). Titanium retainers and steel cups included.

Price: $225

Select street or racing for correct bottom washer thickness

Black diamond stock size valve set with stem tips specially machined for Beehive valve springs only.

Price: $220 set

Stainless steel big valves with stem tips specially machined for Beehive valve springs only. Same as in our complete big valve & spring kit above. Oversize valves come without black coating. Tips are induction hardened. Requires re-angled valve guides.

Price: $400 set

Choose sizes:

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 (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 wonderful longer lasting material. Expansion slit allows a more precise fit than stock bushings. Includes uppers & lowers. A drop in kit.

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, Modifications for easy timing make 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 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

SPECIAL OFFER - One set of 73.5mm medium compression pistons with "Hard tuff" coating to prevent scuffing and extend skirt life. This is the same coating used on Venolia pistons for top fuel motors (visit hardtuff coating). Its too expensive for us to continue offering it so this is a one time deal. The piston diameter is increased by .002" which increases the ring gap - so gapless rings are highly recommended (see gapless rings above). Comes with rings (add gapless), clips and DLC pins. Bore will need to be 73.55mm/2.8957"

Price: $435 set