Sam’s Honda CB 350 idles properly

Hot damn!  It turns out that with a little patience and a little research (ok, maybe a lot of both), you can get things done.  After my first start-up of the Honda CB 350, with its new carbs, exhaust, coils, etc., I was determined (but not at all confident) to get it running properly. 

The problem, as you may remember, was that it would idle really high, around 3500 rpm, so I could never let it run for more than a second or two. So, after some poking around on the internets and some hard thinking, I came up with a three pronged course of action:

First, I ordered some new main jets.  On these Mikuni carbs, the mains only affect ¾ to full throttle, but I was pretty sure that the 200s my set came with were too big, and that I’d need them down the road.  So in went a pair of 155s, which seem to be as close to standard on a stock CB350 with 2-1 exhaust as there is.

Second, I ordered some new cable nipples so I could lengthen my throttle cables.  I’m pretty sure that even at their slackest adjustment, they were still lifting on the slides a little bit.  It wasn’t until I received the new nipples that I realized that I could just remove the cables entirely – they’re not needed if all I want to do is idle!

Finally, and perhaps most importantly, I replaced the rubber carburetor boots with Mikuni specific models from Dime City Cycles.  They’re a much better fit, and much softer rubber, minimizing any air leaks I might have had.

With these changes made, I kicked it over.  Nothing. Tried and tried and tried, and it felt like it wanted to start, but maybe wasn’t getting enough fuel?  Turned the choke on and there it was: no adjusting necessary, just idling beautifully at oh, maybe 800 rpm.  And jeeeez, does it sound good.  Check out the video at the end of the post.

So, unless I’m totally wrong, that for Mikuni VM carbs the choke lever is on when down, I need to figure out how to run it without the choke on.  I think all I need to do is adjust the air screw (these carbs are infinitely adjustable, and there are separate screws for idle and air mixture).  I will say, however, that so far they are worth every penny.

In other news, you might notice from the photo and video that I tightened up the custom exhaust a little (it’s now ready for finish welding), and threw on my new 2” oversize shocks.  Whoa!  It raises the back end so much that the center stand is now more of a kick stand.  Not sure that it’s ideal, but it’ll be easy to fix down the road.  Next up is to hide the battery, attach a tail light and license plate, finish the forward controls, and mount my rearsets.  Hope to get some of that done this weekend.

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