How-To: Remove Motorcycle Carburetor Welch Plug

Share This Post

The most important passage to clean during a carburetor rebuild may be hiding from you under a welch plug. The factory will install a hard to remove plug right above the fuel adjustment screw. I’m not sure of all the reasons why they install them, maybe to prevent people from tampering with the fuel/air mix due to EPA concerns.

motorcycle carburetor welch plug removal

 

Why Remove Them?

The fuel screw under the welch plug & the pilot jet meter fuel for the idle circuit. This is the first and most common passage to get gummed up, since it is the smallest orifice. Also, after the carbs are cleaned or rebuilt, you really need to adjust the fuel screw(s) to what your engine WANTS, not what the service manual calls for. The service manual may be a good starting point, however they are usually too lean (I’m talking about 4 stroke street motorcycles here). Better throttle response and performance can be achieved with proper pilot jet and fuel screw settings.

 

How-To: Tune Your Fuel Screws

Here is a video that explains fuel screw adjustment once your carbs are clean. See this post on pilot jet sizing.

 

Tools

I have no idea what brand my pick set is. In fact I have several sets and have “custom” bends in some of them.

Pick set from Amazon

 

Comments

Has this blog post or video helped you out? Please comment below.

 

JOIN OUR NEWSLETTER
Like my articles and How-To videos? Enter your name and email to get notified when new content becomes available.
No spam. No BS. No sharing email.
Liked it? Take a second to support Matthew on Patreon!

 
  • Cody Richards

    Great video! Companies put those “welch plugs” on the air/fuel adjusters for the sole purpose of emission regulations. They don’t want anyone to change the mixtures, but once you do remove them, it truly makes all the difference in tune-ability and dialing those carbs in properly! Great read! Keep up the great work!

    • Hi Cody, you have that exactly right. The fuel screw settings are also set really lean in most cases. If you hit 3 turns out on the fuel adjustment, consider bumping the pilot jet 1-2 larger than stock. That alone makes a huge difference in performance.

 

Categories