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


Norton lightweight pistons. 1/3 less weight 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). Crank rebalancing is not required (balancing).

Price: $435 set

Select Bore:


Norton Ultra Hi compression domed piston kit for racing fuel only. These 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. 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 gasoline 850s with combustion chambers larger than 51cc (approx 12:1 C.R.). Crank rebalancing is not required (balancing).

Price: $535 set

Select Bore:

Piston skirt coating. This will will add .002+" more diameter to the piston (.001+ on each skirt). The pistons will then have a slight interference fit when fully hot but the slippery coating will prevent scuffing or scoring. The coating will polish off at the interference area on break in and leave you with a piston that is tighter in the bore than you would have with an uncoated piston. Life of the piston is approx doubled compared to a bare aluminum piston. Reduced friction increases HP.

Price: $119 for coating two pistons

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). Choose short stroke 6.57" length rods for 80.4mm stroke racing cranks. Other lengths and pin diameters available (more info).

Price: $690 set

Select stroke:

ULTRALIGHTWEIGHT 6.4" Carrillo rods. For Atlas and solid framed street 750s up to 75 HP and 500 to 650cc Dominators. Special order lightweight pistons available for 500 to 650 Dominator twins and custom applications. Add $100 to our price for a pair of special order pistons or ultralight rods. Regular price still applies to a four piston order. Contact us for details (ultra-lightweight info).

Totalseal type gapless rings. For perfect compression and sealing, this upgrade will convert your regular 2nd 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 more kickstart pressure (longer kickstart lever available from RGM) (see leakdown test).

Price: $50 for two piston ring sets

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

Price: $50 for two piston ring sets

Select size:

High strength .708" DLC pins (diamond like coating). As supplied with our lightweight pistons. Will not fit stock pistons or rods. 750cc pin = 51 grams, 850cc pin = 58 grams

Price: $150 set

Select size:

Wrist pin clips for JS lightweight pistons.

Price: $6 set

One piece crankshaft. Made from 4340 nitrided steel for the ultimate in strength and reliability. Standard 89mm stroke for 750/850 is in stock. Short stroke and 270 deg offset cranks are special order.

Price: $2295

Complete cam kit. High quality longer lasting radius cam with hardwelded or plasma nitrided lobes, hardfaced lightweight lifters (1/2 the weight of stock lifters), bronze lifter blocks, set of stronger, shorter pushrods to eliminate flexing. Stage 0, 1 & 2 cams use 1-1/8" radius BSA lifters. For stage 3 cams the lifters are specially ground to 7/8" radius. Smooth ramp JS2 & JS3 cams help eliminate valve bounce. Contact us to special order Atlas cams or cams for 270 degree cranks (more info).

Price: $945 set

Choose cam:

Choose cylinder head for correct pushrods:

Radius cam for use with JS lightweight radiused lifters and blocks. Top quality hardwelded or plasma nitrided lobes. Will not work with stock flat lifters. Four cam grinds available. Smooth ramp JS2 & JS3 cams help eliminate valve bounce. Contact us to special order Atlas cams (more info).

Price: $450

Choose cam:

Radiused cam kit including JS cam and your original reground lifters. You must send us your lifters to be reground to 1-1/8" radius. Longer lasting than the stock flat lifter setup. Uses the same cams as our JS radiused cams for lightweight lifters as shown above but you use your original pushrods (more info). Stage 3 cam lifters require extra machining and are special order. Smooth ramp JS2 & JS3 cams help eliminate valve bounce. Contact us to special order Atlas kits.

Price: $650 set

Select cam:

JS Motorsport Bronze lifter blocks for lightweight radiused lifters (lifters not included). Use with our long lasting, custom-grind radiused camshaft. The holes drain directly onto the cam lobes for maximum longevity.

Price: $150

Norton pushrods to be used with JS lightweight radiused lifters and radiused cam only. Will not fit stock lifters. Made of race proven high strength aircraft alloy. Virtually eliminates flexing. Same weight as stock at only 31 grams.

Price: $125 set

Select head for correct pushrod length:

High performance stock size valve & conical beehive spring kit for street or racing. A drop in kit with no machining necessary. Out-performs 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. Longer spring length gives you a better linear rate than shorter conical springs. Includes black diamond valves, custom machined stellite tips, beehive springs, titanium spring retainers, spring seats and spring balancing shims. See big valves below (more info).

Price: $300 set

Select street or racing for correct spring seat

Conical beehive valve springs without the valves. Use our valves or modify stock valve tips to fit (see diagram). Titanium retainers, spring seats and balancing shims included. Late heads with 5/8" dia wire clip guides see valve guide spacers below.

Price: $175

Select street or racing for correct spring seat

Black diamond stock size valve set for JS Beehive valve springs only. See big valves below.

Price: $130 set

Big valves for JS Beehive valve springs only. Equiped with hardened stems and stellite tips for wear resistance. 3mm and 5mm oversize valves are stainless steel. Stock and 1.5mm oversize are black diamond. You must order the Beehive spring kit separately above. All big valves with performance cams require re-angling of the guides to avoid valve clash.

Price: $245 set

Choose sizes:

Big valves for JS Beehive valve springs only. Equiped with stellite tips and hardened stems for wear resistance. You must order the Beehive spring kit separately above. All big valves with performance cams require re-angling of the guides to avoid valve clash. Call for custom orders.

Price: $300 set

Choose sizes:

Special short lash caps to fit valve tips for JS Beehive springs. For those who modify their own valves without stellite tips. Also fits stock valves (not necessary for JS valves).

Price: $12 set

Valve guide spacers for JS Beehive springs in late 850s with wire clip 5/8" shoulderless guides. Also for some Full Auto heads with small 5/8" diameter guide shoulders. Not necessary for common aftermarket guides. Fits between the guide and the Beehive spring bottom washers.

Price: $45 set

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). Crushable thin .005" copper wire is provided for looping around the pushrod tunnels to prevent leaks. See pliobond sealant below (more info).

Price: $39
Select gasket:  

Custom Copper Base gasket for Norton Twins. .021" thick. See pliobond sealant below. (more info).

Price: $30
Select motor:  

High compression .003" thin head gasket rings. Comes with .005" thin crushable copper wire for eliminating oil leaks at pushrod tunnels and oil return hole, making this a reliable and trouble free setup. This is the easiest way to raise compression approximately one point (10%). See pliobond sealant below (more info).

Price: $30
Select motor:  

Sealant for copper gaskets. High temp contact cement. Apply to each surface. The best head gasket sealer I've found (sealant comparison).

Price: $8

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

Aluminum fork sleeves. Get rid of annoying metallic "clunking". Now you will have a hydraulic bump stop at the top and bottom limits of fork travel as things 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 for the forks make these work when others don't (more info).

Price: $55 set

One piece aluminum rocker spindle covers. Stainless steel button head allen screws and aluminum washers included. Eliminates leaks, neat and tidy.

Price: $45 set

One way reed valve breather. Eliminates positive case pressure and oil leaks. Easy installation with no modifications or machining necessary. Fits 750 left side case breather vent, 850 timing case, Combat or Maney case lower sump mount and all front Tac mounts. Also fits the MK3 elect start timing case with the shorter aftermarket starter (contact us when ordering for the original prestolite starter) (more info).

Price: $195
Select motor:  

1/32" thick reusable fiberglass reinforced silicone gaskets (go here to order gaskets). You can tighten them down and they won't squish out like regular silicone. Available for rocker covers, oil junction block, rockerspindle covers, tacometer, timing cover, sump breather, JS reed valve breather housing, tranny cover, intermediate tranny, tranny inspection and Atlas magneto. High heat tolerant and oil tight. Sealer unnecessary.

Norton race manual. A must for every Norton racer - Novice or expert. Contains priceless info gleaned from some of the greatest tuners of our time. Subjject 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 monoshock racing frames and more.

Price: $25

Norton Monoshock Racing Chassis plans. Includes complete details on tubing geometry, tanks, seat and implementation. The photo shows one of the fastest Norton roadracers ever built and the last Norton to get on the AMA podium (3rd place battle of the twins at Willow springs in 1990 against a field of Ducatis). In CD format. Autocad 2000 or later is required to view the drawings. Optional twin shock configuration included (more info).

Price: $10.00

Norton porting specs. Includes Autocad drawings of "Full Auto", "Axtell" and stock Norton ports plus Harley XR 750 "Cobra head" ports adapted to Norton. More than 50 photos, drawings and overlays showing comparisons and dimensions for adapting the unique features of these "Narley" ports to Norton heads. 1st, 2nd & 3rd stage performance levels. Instructions for converting 750 into 850 heads etc. Autocad 2000 or later is required to view the drawings. In CD format (more info).

Price: $10

Reduced shank studs and bolts for head and cylinders. The fluted shanks allow the studs to stretch to prevent the threads from pulling out. Also helps prevent bolt/stud breakage. Special triangular reduced shank studs help align the head with the cylinders (go here to order bolt/studs).

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