Motorcycle exhaust systems

Abstract

A motorcycle has an engine with two banks of cylinders. One bank is forward of the other, and its exhaust pipe or pipes passes forwardly, downwardly, and outwardly of the frame, and then rearwardly beneath the side of the engine to reach a muffler and tailpipe. The frame includes a pivoted fork-like rear section with a power transmission. The rear exhaust pipe or pipes extends rearwardly and downwardly between the arms of the rear section, and makes connection with the muffler. In another embodiment for engines with multiple cylinders in each bank, the rear exhaust pipes cross over one another, and extend downwardly outside of the arms. They may also be elongated inside the muffler so the lengths of the forward and rear exhaust pipes are equal. They can connect with one another so as to share outlets into the muffler.

I claim: 
     
       1. In combination with a motorcycle of the type having a front frame portion mounting a front wheel and an engine, and a rear frame portion mounting a rear wheel, said portions being pivotally connected by a horizontally disposed pivot, said rear frame portion comprising a pair of laterally spaced-apart arms, said engine comprising two banks of cylinders, one disposed forwardly of the other, an exhaust system comprising: a front bank exhaust pipe extending from said front bank, downwardly and to the side of the said frame and rearwardly;   a rear bank exhaust pipe extending rearwardly and downwardly between the planes of said arms and between the rear portion of said engine and the pivot of said arms;   a muffler having a substantial lateral extent mounted to said frame at an elevation beneath that of said engine, all of said exhaust pipes discharging into said muffler; and   a tailpipe discharging rearwardly from said muffler.   
     
     
       2. A combination according to claim 1 in which there is a pair of each of said front and rear pipes, disposed one pipe of each pair at each side of the centerline of the motorcycle. 
     
     
       3. A combination according to claim 2 in which there is one of said tailpipes at each side of said rear wheel. 
     
     
       4. In combination with a motorcycle of the type having a front frame portion mounting a front wheel and an engine, and a rear frame portion mounting a rear wheel, said portions being pivotally connected by a horizontally disposed pivot, said rear frame portion comprising a pair of laterally spaced-apart arms, said engine comprising two banks of cylinders, one disposed forwardly of the other, an exhaust system comprising: a pair of front bank exhaust pipes extending from said front bank, downwardly and to respective sides of said frame and rearwardly;   a pair of rear bank exhaust pipes extending rearwardly, crossing each other laterally, and then extending downwardly outside of the planes of said arms and forward of the pivot and rearwardly of the rear portion of said engine;   a muffler having a substantial lateral extent mounted to said frame at an elevation beneath that of said engine all of said exhaust pipes discharging into said muffler; and   a tailpipe discharging rearwardly from said muffler.   
     
     
       5. A combination according to claim 4 in which there is one of said tailpipes at each side of the said rear wheel. 
     
     
       6. A combination according to claim 4 in which all of said exhaust pipes extend in said muffler to such an extent that all of their lengths are substantially equal. 
     
     
       7. A combination according to claim 6 in which said front and said rear exhaust pipes join in pairs, and each pair discharges through a single opening into said muffler. .Iadd. 
     
     
       8.  In combination with a motorcycle of the type having a frame portion, a front wheel dirigibly supported by said frame, a V-type engine supported by said frame with its crankshaft axis extending transversely to said frame, trailing arm means pivotally connected to said frame for pivotal movement about a transversely extending pivot axis, and a rear wheel journaled by said trailing arm means, an exhaust system comprising an exhaust device extending transversely across said frame for substantially the entire width of said frame and juxtaposed at a level below that of said engine and in proximity to said trailing arm pivot axis, a front bank exhaust pipe extending from the front bank of said engine downwardly and terminating in said exhaust device, a rear bank exhaust pipe extending downwardly into said exhaust device, said rear bank exhaust pipe being positioned ahead of the said rear wheel and ahead of said pivot axis, and a tailpipe discharging rearwardly from said exhaust device. .Iaddend. .Iadd.9. A combination according to claim 8 wherein the engine overlies at least in part the exhaust device. .Iaddend. .Iadd.10. A combination according to claim 8 wherein the front bank exhaust pipe enters the exhaust device at one side thereof and the rear bank exhaust pipe enters the exhaust device at a central position therein. .Iaddend. .Iadd.11. A combination according to claim 10 wherein there is a second front bank exhaust pipe extending from said front bank rearwardly and entering the other side of said exhaust device and a second rear bank exhaust pipe extending rearwardly and downwardly forwardly of the rear wheel and 
     
     
        entering said exhaust device at the center thereof. .Iaddend. .Iadd.12.  A combination according to claim 11 wherein the engine overlies at least in part the exhaust device. .Iaddend. .Iadd.13. A combination according to claim 11 wherein the engine drives a drive shaft that extends to one side of said frame for driving said rear wheel, one of the rear bank exhaust pipes being offset relative to the other of said rear bank exhaust pipes away from said drive shaft for providing clearance therebetween. .Iaddend. .Iadd.14. A combination according to claim 13 wherein a pair of tailpipes extend from the opposite sides of the exhaust device and rearwardly on opposite sides of the rear wheel. .Iaddend.