cutting down coffman pipe

[chrisdoc0608]

i remember reading something about how the coffman pipes have the multiple ridges in the stinger cone so you can cut them down. If i recall it was for better bottom end, i cant seem to find the thread that i read that in. right now i am running a ported 650, 3 degree advance, lightened flywheel, 180psi, 46mm, and all the other little bolt ons, here is my pipe as you can see there are two ridges on the stinger pipe, would it be worth cutting one off to shorten or not if i am looking for more bottom end response.

http://www.pwctoday.com/attachment.php?attachmentid=105866&d=1205619940

 

[OCD Solutions]

I thought cutting it down was to get better top end?

 

[chrisdoc0608]

yea it is, i was mixed up... i found some info on the sonic waves so i guess it would be more beneficial if i get a wider coupler and extend the length of the pipe

 

[jeepmark4x4]

Chris, sounds like you have a pretty mean 650 setup. Your best bet though would be to save up for a 61x cylinder setup and port the coffman exhaust manifold. I pretty much had the same setup on my square nose you are running; than did the 61x swap for 400 dollars including cylinder/head/pistons and it was the best modification you can do to an old 650.

As for cutting down the chamber, I really haven't heard anything about that but I would leave it alone in my opinion.

 

[Kennay]

Man, just run it like it is. Stop worrying about it. Your engine will be plenty strong.

 

[chrisdoc0608]

it hits really hard mid range, tops out around 49gps (running 12/17 freeride prop) i dont know if it was bored to 701 by group k before i bought it but it will hang side by side with my friends that was, only difference is he has a b-pipe and i feel like i am missing out on some bottom end. i have done everything i can think of next to just upgrading motors, but that is out of the question until i get a real job and some $$$. i have got a ww cone, 85mm nozzle, tdr or something similar waterbox, 12/17, jetworks valve, moded cdi, advanced timing, light flywheel, 180psi, porting, scoop grate and 46mm carb..... am i overlooking something that could produce a little more of the hit i want or should i just learn to hit wakes and waves a little faster so im in my powerband.

 

[chrisdoc0608]

Man, just run it like it is. Stop worrying about it. Your engine will be plenty strong.

plenty strong is a statement of opinion mr 760

 

[ags0702]

B pipe for sale $600 :deal:

Your ski is quick, don't mess with it!

 

[JAKESPEED]

pics for that bpipe?

 

[ags0702]

pics for that bpipe?

Actually not for sale, sorry....

I like to tease chrisdoc0608 because he wants a b pipe...:veryhappy:

 

[nikad58]

it hits really hard mid range, tops out around 49gps (running 12/17 freeride prop) i dont know if it was bored to 701 by group k before i bought it but it will hang side by side with my friends that was, only difference is he has a b-pipe and i feel like i am missing out on some bottom end. i have done everything i can think of next to just upgrading motors, but that is out of the question until i get a real job and some $$$. i have got a ww cone, 85mm nozzle, tdr or something similar waterbox, 12/17, jetworks valve, moded cdi, advanced timing, light flywheel, 180psi, porting, scoop grate and 46mm carb..... am i overlooking something that could produce a little more of the hit i want or should i just learn to hit wakes and waves a little faster so im in my powerband.

I would check and see if its bored to 701 before anything.. If its not there is alot to be had from just a bore and pistons.. A ported 650 bored to 701 will run circles around a stock 701 along with more bottom end..