Topic: short head pipes

[pinnacle]

hey guys i would like to know why a short headpipe would lead to burnt exhaust valves? does the exhaust gas not get expelled quick enough and therefore cause the engine to run hotter? and how short is to short to cause this? is it normal to see flames come out of pipe under hard acceleration followed by popping? would installing baffles straight into the headpipe help with this? sorry about all the questions but i am just trying to grasp the concept on how changes like these can impact the engine and performance. this mod was done to my 84  honda vt 750 but figured principle applied to any engine and you guys all have more experiece on these matters than i so school is in session....

[dave500]

short pipes will cause your motor to run leaner than it should,you can baffle them somehow but a proper muffler gives more room for the hot gasses to expand,youll see flames alright.

[stueveone]

How short are we talking? I just cut a several inches off the silencer on my CycleX exhaust, doubtful that was much to change it. I mean, it's not like we're talking about a 2 stroke exhaust right?

[pinnacle]

well from the engine exhaust port to the end of the pipe maybe 30 " of 2" pipe. i took the muffler off so i could wrap the pipe with tape and wasn't sure if i could wrap a megaphone shaped muffler so i was going to build a shorter length of pipe with some sort of baffle as it is loud and i dare to say louder than some hd's out there....then i read that it may cause burnt exhaust valves due to the loss of the scavenging effect....i just want to make sure it will not damage the motor....

[dave500]

i run a straight through automotive resonator,with the outlet stepped down to about 30mm.