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Post by scooter on Oct 11, 2014 5:04:14 GMT -5
How important is exhaust back pressure? I cut off the back end of my muffler and removed a loose piece of metal tubing that was rattling around in the muffler. I like the sound of the bike with the back end open but I am concerned that back pressure may be an issue.
What are the effects of running a muffler with the baffles removed and/or the back end open?
How much back pressure does the engine need and how does it affect performance? (I didn't notice any improvement in performance but it sounded nice, and not too loud with most of the baffle still in it.)
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Post by xyshannen on Oct 11, 2014 7:54:21 GMT -5
You still have plenty of back pressure from your stock header. But making the exhaust flow freely will make you run lean. And if you are too lean you could be causing your engine to run hot. A simple up 2 sizes on your main jet in your carb should take care of it. Be sure to read Allyoops carb adjustment how to.
I'm assuming you have a gy6..and if so more flow more go. I have on my 150cc gy6 a real 1 inch performance header with a straight through muffler with the baffle removed and my scoot runs like a bat out of h*ll. It took some fiddling with the carb to get it set right but once I got it all sorted it now runs great.
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Post by pmatulew on Oct 11, 2014 8:01:29 GMT -5
Changing the amount of restriction in the exhaust system will change the air flow rate through the engine. That will change the air/fuel ratio. (The fuel flow is fixed by the jet size in the carburetor.)
If you like it more open then you'll need to increase the size of your main jet one or two steps to compensate. Otherwise the engine will run lean and burn a valve.
Most of these exhaust systems aren't really "tuned". They are just sound suppressors. So you're not losing any esoteric benefits from changing the sound qualities.
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Post by pmatulew on Oct 12, 2014 7:48:04 GMT -5
Back pressure is sort of a new-fangled notion.
Engine porn at 2:00
More at 2:45
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Post by scooter on Oct 12, 2014 8:09:44 GMT -5
Thank you, Dahling. I think my scooter is getting jealous!  |
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