Bonneville America Forums Forums Technical Forums Performance Mods carberator drilling

Whats involved in carberator drilling and how does it really help.

Drilling the slide allows the slide to rise faster allowing more air to flow into your engine faster. It works off of a vacuum and the larger hole allows more vacuum to open it up quicker. The short and sweet of it.

It is pretty simple to do. Remove the top of the carburetor (4 Screws) remove the vacuum diaphram, spring and slide with needle. You drill the existing hole to 7/64 or something like that. check the size before drilling I guess the newer bikes already have the slides drilled to the larger size. Now you just reassemble in reverse. The toughest part is getting the diaphram to sit back in the groove that it came out of, it can be a real pain in the A$$.

So, No need to drill a 06 speedmaster?

Check with some others with that new of a bike, I think you are already OK but check with someone else with an 06 to be sure. No need to tear it apart if it is already done. I have an 02 but I have read that newer bikes already have this modification done.

Here's the info.

slide drilling

Now that's one clear pictured, simply detailed "how to" section. Just curious, how's it affect the ride. Quicker off the line? Feel more powerful from the start? Any descriptions from someone.

Throttle response is much faster !!!!!!!!!!!!!!

I didn't notice any quicker off the line, primarily better throttle response.

do you have to do any re jetting

no