Hey I found this is this thread break> I can't find any more info on modding a gurtner carb for the motobecane.
can someone explain this a little better? maybe a pic
Author: Paulvolio (---.bos.east.verizon.net)
Verified User: paulvolio
Date Posted: 09-29-08 08:24
Attachment: 1222691065_fast_moby.jpg
The restriction in the engine isnt in the exhaust it is in the cylinder ports.
The pipe will not restrict performance untill you port the engine the flow limit on it is around 8krpms
You can try modding the infuser tube on the gurtner, If you use a small round file in a drill you can ream out the square-ish base of the infuser then file the sides of the tube with a flat file.DO NOT SHORTEN THE TUBE!!
This will make the profile of the tube smaller effectivley increasing the airflow around it. It is like having another quarter throttle to use.
I have hit well over 50 with the modded gurtner a good port job some head work and a custom tuned pipe on my moby
The stock exhaust would still let me get to 40 with pretty good low end.