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· prevented easy mass-production of the engine. Therefore, the decision was made to go with three inlet valves and two exhaust. With the adoption of triple inlet valves, the effective intake area (valve circumference x valve lift) is increased. Valve angle is reduced, a critical factor in achieving the optimum hemispherical combustion chamber shape. The outer inlet valves are set at 17.25° from vertical with the central one at 11.5°. Both exhaust valves are set at 13.75°. These figures compare with near-20° angles on typical four-valve engines and in the region of 30° for conventional two valve motors. The narrower valve angles keep down the combustion chamber volume for a higher compression ratio, with the nearly-vertical central inlet valve giving a swirl effect to accelerate £lame travel around the. chamber during combustion. Thus, as well as increasing cylinder filling, the triple inlet valves aid more complete burning of the charge. Piston design is also calculated to enhance combustion efficiency. Unusually, the piston is slightly concave at its crown, as well as having the normal cutaways for valve clearance. The depression in the piston crown works with the hemispherical cylinder head to promote a swirling, circular flame pattern that results in complete scouring of the combustion chamber and total explosion of the fuel. The combustion process is completed very quickly, as a result, and power waste through heat loss is reduced. Combustion energy is eHiciently converted into motive energy. Evidence of the final benefi t of the five-valve system is the comparison 9f individual valve; weights. l,Jnlike four-valve technology, the lDtake valves on the five-valve system are smaller and lighter than the exhausts. On conventional two or four-valve engines, the opposite is usually the case. With the FZ750 five-valve head, the exhaust valves remain the same weight as in a four-valve configuration but each inlet valve is 20% lighter than a comparative four-valve component. That's a significant weight reduction for valves in an engine that will turn in excess of 10,500 rpm. There is another significant byproduct of lightweight valve gear, especially as the FZ750 has cams actingdirectly on valve buokets, with no rocker arms. Lighter valves place less load on the camshaft, thus reducing wear of this critical component and lessening the need for adjustments. Interestingly, the total intake valve area of the five-valve system is less than the four-valve configuration, and valve lift is reduced. However, because three valves are being lifted rather than two, and because three valves have more total circumference than two, the actual intake area around the valve's head is increased by more tltan 10%. This increase in eUective air intake increases power. Both horsepower and torque are increased by about 10% and the spread of torque is much wider. The five-valve head, therefore, improves both top speed and acceleration. The FZ750 engine is both extremely flexible and immediately.responsive to throttle opening. Test results have proven that the configuration also brings abouta 5% improvement in fuel consumption over a four-valve unit. The new, compact hemispherical combustion chamber increases the amount oE space around the spark plug compared to the comparatively narrow confines of a pointed pentroof combustion chamber. This promotes quicker combustion, less heat loss and means less fuel is used per mile covered. • 0 0 John Martin on a Can-Am 250 LCIASE points lead in Minnesota, Sept. 16, 1984. ~ , "1\J\lL1JO~ .... V " ..0 o ..... u o SALE can-am~ The 1985 CAN-AM bikes will be here soon. Your nearest CAN-AM dealer is offering the best deals ever on remaining 1984 and a few 1983 models. * You Can't Find A * Save Big Bucks * CAN-AM Features Exclusive Rotax Engines, Tested Durability And Proven Reliability. 8etter Deal On The WORLD'S FINEST DIRT BIKE WE HAVE MORE WAYS ,YO WIN YOU! ,-,.. o er Good Until October 31 st At Participating Dealers Only. -- - Yamllha of Slin luis Obispo 1357 Monterey San Luis Obispo, CA 93401 c-.... e-- 805/543-6723 406/278-3481 Reiter's Marina Box 1198 Billings, MT59101 G & G Off Road P.O. Box 536 22n3Hwy 18 Congers AMF 1905 E. 4th 51. Charne, NM 87520 Lubboc:k, TX 79407 4061252-9341 Smith & Jones Coechworils 18048 N. A.,.. W. sosn56·2496 806n97-7449 Motorcycle Spec,alt'es Int'l. 148 Harrison lane J . Jensen Intetiofs 2550 Del\lli St, Slit. 1601 Anchot'~•• AI( 99503 907/278·9224 ~. Valley Cyc~ Alley ~ ven.". CA 92307 609/247-2582 8 I: K SkI'Doo Center P.O. Box 3098 ChioD, CA 95927 916/342-8622 D.H. Cycle • AccessorMis 1432 McHenry Modnto. CA 95361 209/524-1432 Frisbie', Auto Repair 6229 EastSide Road Redding, CA 96001 9161241-1832 JOfQY'S Motorevele SaNtS 2955 N. Wilson Way Stoc*lon, CA 95295 Pueblo, CO 81001 ' 303/542-6032 J 6 J Yamaha 5958 S. Road 106 Alamosa. CO 81101 303/589-6461 Kawasaki West 6851 W. Colfax Ave. Lakewood, CO 80215 3031232-8787 Rampen Cycle 407 Auburn Colorado Springs, CO 80909 3031574~6399 M _... A &' B Cvcte Sales 111 N.Main Conrad, MT 59425 Minoula, MT 59801 406n28-5341 Monty White Sports 3547 Harrison A.,.. Bune, MT 69701 406/494-5880 Z & Z Motors.ports Box 725 E. HeMma. MT 59635 4061227-6485 P.O. Criiv Mountain Can-Am Box 162 Clyde Park. MT 59018 spons Center of Grand Junction 2585 US 6 & SO Grand Junction. CO 81501 406/686-4921 3031243·7148 PerfOfJn8nca Cycle 240 S. Loera Anlheim, CA 92802 N....... Valley Ski-Coo 714/991-7210 Snyder', Chain Saw Sel'\lice 1898 SoperiOf St, 303/872-3444 The Cycle Shop 314 "E" St. Fairbury, NE 68352 209/463·2912 Burney, CA 96013 916/335-2579 Warren', Har~·Oavidson 321 N. MIIin St. SaliMI, CA 93901 408/424-1909 P.O. Box 805 Ho1Chkiss, CO 91419 'doho Panhandle Prep. 850 N. 4th 51. Coeur d' Alene, 10 83814 208/661-9663 402n29·3757 N_ Michael', Cycle Wl)(ks 1923 Hwv SOW. Carson City, W 89701 702/883-6111 CompetitlOf'l Cyele 606W.~ Gallup, NM 87301 505/863·5263 Harold's HU$qVarne 313 Louisiana SI. Albuquet'que, NM 87108 505/266·9587 North D.-ota Bennie's Cyele 5efviee 3701 S. Broadway Minot, NC 58701 701/852..()874 Oklahome Hugo Kawesakl & Can-Am P.O. Box 239 Hugo, OK 74743 405/326-2261 MId·Cel Motorcycle Sa'" 2232 S. Air Depol Blvd, Oklahoma City, OK 73110 405/732.Q212 Mud, Sweat & Gear. 4303 Cache Rd. Lawton, OK 73505 4OS/355-1808 T.... AtNrlllo Hobby House 4127 W. 34th St. A.merillo, TX 79109 806/355-2921 Lewis Ashby', Cycle Hut 1021 E. 7th SL Odessa, TX 79761 9151337-3297 The Cycle Shack 5218 - 341h SI. Hurst, TX 16053 8111268-6875 Utah Jerry's Cycle 209 N. W.shington 81Yd. Ogden, UT 84404 801/393-3413 SleW8n', 6601 S. State Sail Lake City, UT 84107 9011263-2600 Twin Wheel Cycle 602 N. Main laytOn, UT 94041 801/544.Q717 W.ahlngtOn 125 N. Central Avenue Kent. WA 98031 206/852·8670 Wyoming K-Moti.,. P.O. Box 415 Green River. WY 82935 307/875-9205 MX Cycle & Repeir 2616 Cowgill Ad. Cody, W'( 82414 307/587·2454 13