|
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 Technical |
| Camshafts |
|
Increase the RPM limit of your Norton and reduce the danger of valve float with JS Motorsport's Radius Cam and Lightweight Lifter kits.
I have personally tested these components beyond 8000RPM. JS Motorsport's Radius Cams are superior to standard flat lifter cams in all respects. Our cam nose is broader (similar to a roller cam), and combined with our "tested" BSA-style radiused lifters substantially reduces camshaft wear. The durability and long life of our cams and lifters will save you money in the long run. This technology was initially developed years ago when factory sponsored Nortons were winning US dirt track races. We have refined this development to reproduce the pinacle of performance for our vintage super bikes, for both street and track.
All JS Motorsport cams are hardface welded for the ultimate in reliability.
|
| DESCRIPTION OF JS MOTORSPORT RADIUS CAM |
CAM LOBE LIFT
| VALVE LIFT |
DURATION MEASURED AT .040" CHECKING CLEARANCE |
LOBE CENTERS |
COMPARE TO FLAT LIFTER NORTON CAMS LISTED BELOW |
| The perfect cam for stock street Nortons and stock broad power band performance with a slight overall improvement, stock springs OK. Smooth idle with good low end torque. BSA A65 Spitfire intake lobe grind on intake and exhaust. |
.335"
| .380" |
265° |
104 |
Performance close to Stock Norton Commando cam but with slightly more lift and duration. |
| 1st stage hot street and all around racing for 4 or 5 speeds with strong mid range. May have hot rod idle depending on engine size. Requires racing springs for track. Great for 750s. This is a copy of the famous Axtell #3 cam but for lightweight radiused lifters. Note that Ron Wood achieved 84 hsp with an Axtlell #3 cam in his 750 flat tracker. |
.345"
| .395" |
278° |
104 |
Performance same as Axtell #3 and similar to Peter Williams PW3, Megacycle 560NR |
| 2nd stage full race cam with excellent mid & Hi RPM power for racers with 5 speeds and hot street 850s & 920s. Requires racing springs. Hot rod idle. |
.360"
| .410" |
280° |
105 |
Performance similar to Norton 4S, Steve Maney cam, Megacycle 560NSS, Norris RX |
| 3rd stage cam for serious Hi RPM racing with 5 or 6 speed, Sifton 460 grind. Not for street. Rough idle. Requires strong racing springs. Used on factory sponsored Hi power US dirt track 750 short strokes. Lots of top end power. For stage 3 the lifters must be ground to 7/8" radius. |
.390"
| .440" |
283° with 7/8 radiused lifters |
106 |
Performance similar to Megacycle 560-D+ (Norris D grind), Norton 7S. OK for all out short strokes and large displacement racers |
|
Lifters |
|
|
Weighing less than half than original Norton flat lifters, JS Motorsport's radiused lifters make your Norton more free reving while reducing stress, friction, wear and overheating of the valve train. Reducing the weight enables your valve train to operate more acurately and effeciently. Pushrod and rocker arm flex is minimized, allowing the full lift your cam was designed to deliver and allowing use of more aggressive profiles than would normally be available on cams designed for heavy inefficient stock Norton lifters.
Expect greater relibility and longer service with street bikes.
Energy saved on the valve train goes to the rear wheel and wil increase power over the entire RPM range, making your motor behave as if it had an overhead cam. |
| Pushrods |
|
JS Motorsports Radius Cam and Lifters require approximately 3/8" shorter pushrods than stock. Our pushrods are made of high strength aircraft quality aluminum to reduce flexing and are superior in strength and slightly lighter than stock push rods. They also have a higher buckling strength compared to steel pushrods of the same weight. We do not recommend steel pushrods because when hot, aluminum cylinders will expand at a different rate than steel, causing the valve tappet clearance to increase dramatically.
|
|
Complete instructions are provided with each cam kit. The only modification you must make is to drill and tap the cylinders for the provided set screws as in the photo below.
|
|
You must use radiused lifters with our radiused cams. Stock flat lifters will tangle the valves. Conversely, if you use radiused lifters on a cam designed for flat lifters you will lose duration and power.
|
|
|
