rls@ihuxf.UUCP (Richard Schieve) (05/29/84)
Could some motorcycle expert out there please explain why multiple cylinder motorcycle have a carburetor per cylinder. Why not use an intake manifold and avoid all the carb balancing problems. Please excuse my ignorance but I maintain my own cars and just purchased my first more than one cylinder motorcycle. All the vacuum gauge playing around, sounds like a pain. I think other readers might be interested in the replies. Rick Schieve
tiberio@seismo.UUCP (Mike Tiberio) (05/30/84)
Motorcycles have hot cams compared to cars. What I remember reading as an excuse for multiple carbs is that intake vaccum/pressure variations would upset carburetion if the cylinders shared intake manifolds. Also giving each cylinder its own carb allows you to mount it closer to the port.
an@hou2h.UUCP (A.NGUYEN) (05/30/84)
-- In one word: high performance. Well all right, two! One carb for each cylinder can flow more air than one carb for all cylinders. Plus you can jet them differently for each cylinder, which is useful on air-cooled multi's that can't cool all cylinders evenly. Ducati V-twin's have one cylinder in front of the other and the rear always runs hotter. Of course, balancing and jetting are problems. The Honda 250cc 6 cylinder racing bike (RC-166?) of the late sixties had six carbs! They changed jetting by swapping the complete set! There are exceptions. The Benelli 6's (750 and 900) have 3 two-barrel carbs, and the new Suzuki 550E's have 2 two-barrels. Au "You'll never see a Jap Superbike with less than 4 velocity stacks!"
mikey@trsvax.UUCP (05/31/84)
#R:ihuxf:-222300:trsvax:57700021:000:1175 trsvax!mikey May 31 09:25:00 1984 Some bikes did use one carb for multiple cylinders. Also as a side note, there is a conversion kit for the CBX that lets you run a single four- barrel carb on the six cylinder engine. However there is a turbo in the middle. If you're talking about one carb for three or more cylinders, the problem becomes one of mixture being consistant from the inner cylinders to the far cylinders from the carb. On fours, I think there is also difference in mixture between the center cylinders and the outside cylinders. I don't think that you would have any of these problems on twins or watercooled engines. I think here the problem is response time for the throttle. Some older Hondas used to have models that came both ways. For example the old 160's and 175's. Sure, more carbs cost more, but it is not that much and with everything being hyped for performance as it's main product, multiple carbs are the logical solution. As for how much time delay difference from the different setups? I'd bet that there would be a more noticable difference from carb types on some bikes, than from the number of carbs. mikey at trsvax 55, it's not just a good idea, it S*CKS!