I need to know the inner and outer diameter of atc 90 exhaust as I am going to make my own straight pipe with resonator. What is the biggest size pipe I can fit on the stock head?
First Time Rider
Arm chair racerNew to the board
I need to know the inner and outer diameter of atc 90 exhaust as I am going to make my own straight pipe with resonator. What is the biggest size pipe I can fit on the stock head?
1983 ATC 185s 200 jug bored .20 9.5:1 Naumura piston. Fast as ass when its not stretching the drive chain or stripping hubs.
1986 ATC 250ES. *Total garbage trying to sell it*
1983 YTM 200E. Runs good, forks are super bent but aside from that its mint.
1984 YTM 200L. Barn find, everything is mint except the bottom end is bad... *waiting on a new engine*
Gonna give my 2c since no one has responded yet. Measure the diameter of the largest part of your exhaust port and that will give you a good idea for the head pipe inner diameter starting size.
edit - Ignore the photo of below, it was not the one i meant to attach and for some reason the website will not let me delete it.
Last edited by John_Neary; 02-03-2016 at 12:57 AM.
FACT ! I have no edit button
Arm chair racerThe day begins with 3WW
why do you want to run the biggest pipe you can?Originally Posted by 81ATC185S
bigger is not always better, if you make it too big, you will loose power because the exhaust velocity will be slower than what is optimal which will reduce the amount of scavenging it produces.
First Time Rider
Arm chair racerNew to the board
I don't want to run the biggest pipe, I want to go 1 size up. Ill just get my micrometer out and figure out inner and outer diameter.
1983 ATC 185s 200 jug bored .20 9.5:1 Naumura piston. Fast as ass when its not stretching the drive chain or stripping hubs.
1986 ATC 250ES. *Total garbage trying to sell it*
1983 YTM 200E. Runs good, forks are super bent but aside from that its mint.
1984 YTM 200L. Barn find, everything is mint except the bottom end is bad... *waiting on a new engine*
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