back pressure for exzaust

hey everybody. i built a atv with my 550 maxim motor running str8 headers. that thing pops like crazy. i have the origional muffler to put on the headers, but there not practical. can i just weld plate to the end of the headers with holes drilled through it to create backpressure?

 

Try a 3/4 inch hole that you can always make larger. I stuffed my exhaust with fiberglass mat and expanded metal rolled together and it worked great. The stuff they use in corners in drywall.

 

was this str8 off your headers?

 

Yes, I have an aftermarket 4 into 1. The bike in my "avatar" is someone else's, with factory exhaust. And it's "flopped".

 

timetoride- did you "pink" type fibergalss?? I bought some muffler stuff but would like more.

 

Not pink insulation stuff, that would all just blow out.
Go to an auto parts store, look at the "Bondo" stuff for fiberglass repair.
The non-directional mat, not cloth, or get the proper muffler stuff.

 

backpressure is bad. velocity is good. a plate will create backpressure but doesnt increase the exhaust velocity over any significant length of pipe.

i would recommend re-jetting to handle the W/O exhaust, or put smaller diameter pipe on it to up the velocity.

 

backpressure builds hosepower, with out back pressure you'll burn a valve also, build a muffler, I used a 3" magnaflow, just like a cherrybomb, cut it in half and weld the inside back in it, and put a flang on it, trust me it very loud with a evil sound, but being the rider on the bike it doe's sound different, but build one and let a friend take it up the road, you'll like it alot

 

Back pressure does not build horse power it decreases horse power. exhaust leaks at or near the head is what burns or bends valves due to cold air being sucked into the valves.

 

backpressure = restriction... restriction is bad.

as people have said, you want exhaust flow velocity.