Mod Gurtner carb for moby

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 (

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.

Re: Mod Gurtner carb for moby

Why not just ditch the gurtner and get a 14/12 dellorto?

Re: Mod Gurtner carb for moby

Cause I don't want to spend $80 haha

Re: Mod Gurtner carb for moby

ok, dont. want a 14.12 dellorto? 25 bucks shipped to wherever you are.

Re: Mod Gurtner carb for moby

Spending $$$ on a dellorto is worth it. You can't even tune a gurtner unless you start drilling your own jets. There's three jets for the gurtner, only avail. from handybikes for like $15 ea. Total joke. Get a dellorto.

Re: Mod Gurtner carb for moby

You can get respectable performance out of a gurtner by modifying the infuser tube but it is on the smaller 10mm

gurtner that comes on the stock short intake manifold.

If you have the bigger carb on the long bendy intake then the infuser tube is already as small as it can get.

I have upgraded to a 14 - 14 dellorto sha and have amazing low end but can only get to about 45.

I gave the modded gurtner to Aaron at the freench fix it last month maybe I can get him to post a few pics of that carb...

Re: Mod Gurtner carb for moby

Super sweet deal there Steve! The Gurtner is great for a stock bike but like Andy said, it is not tunable at all.

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