Exhaust building 101....

[streetlegalkarts]

I happen to know a little bit about this...

dose an engine "need or want" back presure? answer is no.

dose cold air hitting hot exhaust have any negitive affects? on a 4-stroke lawnmower engine. posiable but not likely.
that reffers to more proformance engine. like dragster or nascars 350's.
your exhuast vales will never see that much heat.
what back pressure dose do is help in combustion. you would get a more complete burn with a little back pressure. thats why top fuel dragsters use J-pipes.
hopfully that is a complete answer to the question.

 

[Jake.B]

Really no back pressure in a 2 stroke? Have you ever noticed an expansion chamber?

 

[fowler]

he is talking about 4 strokes
and why are u digging up a 5 month old post

 

[Rustydog2010]

Really no back pressure in a 2 stroke? Have you ever noticed an expansion chamber?

And? Theoretically a two stroke doesn't need an expansion camber. Have you ever ran one without it? I have, they run, but like crap.

 

[Jake.B]

Yeah they run terrible? And considering most two stroke engines need to be rebuilt every 200 hours i dont think it particualy good for the engine. You probably loose quite a bit of horse power to.

 

[landuse]

Yeah they run terrible? And considering most two stroke engines need to be rebuilt every 200 hours i dont think it particualy good for the engine. You probably loose quite a bit of horse power to.

Who recommends that 2 strokes should be rebuild so often? I have never heard that one before.

 

[Jake.B]

My neighbor who is a very experiance mechanic and 2 stoke recreational racer said to me that about every 200 hours to rebuild the top end. This may just be for max performace but i beleived it because he knows alot.

 

[fowler]

All high performance motors require high maintainence

I'm sure u will find the average joe has never rebuilt his dirtbike

 

[Jake.B]

Yeah your probably right hah.

 

[madmeatcleaver]

this is what i did for my little 6.5 tecumseh so that it wouldn't be so loud around the neighbors. I'm pretty sure there is some back pressure, cause it left the silencer on the tip, but it is much quieter.
go or bad for the engine?

 

[Rustydog2010]

Looks like it would have less back pressure than stock tbh. I don't know the make up of it though.

 

[Bluethunder3320]

is that super quiet?

 

[madmeatcleaver]

is that super quiet?

Pretty much the only noise while idling is the engine internals and clutch, when going full throttle it has a nice lower tone that isn't nearly as piercing and deafening.

and I have a universal screw-in muffler stuck inside of the end of the big muffler which is clamped onto little one, cause I don't have a welder yet. and the rest of the piping is 3/4" galvanized pipe joints and connectors.