Keeping an outdated carb on a bike just because a Harley comes with it is like saying McDonald's has the best hamburgers in the world because they sell more of them than anyone. I put a Mikuni HSR42 on my 06 Deluxe and woke up my bike in a big way and I can adjust the idle without a screwdriver. It still uses Harley throttle cables and air cleaner bolts right on. I love Harleys and have been riding since 1971 but some parts just need changing.

 

Thank you everyone. I tore it down and sure enough hole in the diaphragm. I'm going to go ahead finish the upgrades to the cv40 (rebuilt it once 40000 miles ago) while I do the rebuild this time. Thanks again!

 

What "upgrades" are you considering....??

I only ask, because I remember back many years ago, there was a popular mod where people would drill out the hole on the underside of the slide to 1/8" (I believe I got the size correct, been a few years). It was all the rage... Then it was found to cause more harm than good.... It actually led to erratic operation of the slide, and fell out of favor with the performance crowd... There are still a lot of old articles around, especially if you just do a google search, that claim that as a beneficial, performance mod...

I did it to my '89 Heritage (first year with the CV40 carb I believe) and shortly after, the bike ran poorly... I replaced the slide with one that had the factory sized hole. The bike immediately ran better, and it ran great for the remainder of the 40K miles I owned it... That included an annual trip to Yosemite via Tioga Pass (10K feet) from San Diego (sea level) and that engine/carb never missed a beat...

Good luck with your rebuild...