Quick Muffler question

[Anonymous]

On a bike with 2 mufflers... is it a problem if on of them is factory and the other is aftermarket? (besides looking funny.....) Will it cause backpressure problems? Or cause the engine to run poorly?

[SqDancerLynn1]

It may make it sound funny. Why not change the other one to match

[wizard]

It might make it run very funny. Especially if the premuffler has been removed to accomodate the aftermarket. Unless they are both creating the same backpressure, the cylinders won't be running evenly.

[Anonymous]

Can it cause damage to the engine?

Everything before the muffler looks the same... you would assume they would have replaced it with a muffler of the same specs....

[argonsagas]

It might make it run very funny. Especially if the premuffler has been removed to accomodate the aftermarket. Unless they are both creating the same backpressure, the cylinders won't be running evenly.

Excellent point. It is easy to create large differences by changing only one muffler, and that can upset your fuel usage, power output, or damage your engine. Both mufflers should have exactly the same characteristics. If you are not certain of the new one, buy two and be sure.

[lhanscom]

With a stock header all the pipes join into 1, then back out to 2, so a 4 into 1 into 2 setup. Because of this, wouldn't the back pressure equalize?

[wizard]

Assuming that the mufflers don't have identical restriction, the backpressure to the exhaust ports will fluctuate, even with the 4 into 1 into 2 setup that you describe. The left muffler will exert more back pressure than the right muffler, forcing more of the fluid (exhaust gases) to flow to the right muffler until it can't handle the volume. Now the right muffler will be exerting more back pressure, forcing the volume to the left side. Since the assumption is made that the mufflers have unequal restriction, this will not take the same amount of time. This should produce a "thrumming" sound in the exhaust system that rises and falls in different time increments.

Additionally, the exhaust ports will see different pressures. This translates to uneven stress levels on the gaskets, the valves, and even the piston surfaces. Whether this is enough to actually cause any damage I can't say.

What I can say is it would probably be a good idea, even if only for the appearance of your ride, to install matched mufflers.