Okay, long, lousy story short, I was working on My bike's carb, had it stripped down for cleaning, repair and mods,  and the wind picked up and blew a bunch of small parts away, including My original pilot air #1 jet apparently.
Good news: Before embarking on this repair/refit fiasco, I bought a bunch of extra parts just in case (because crap like this always happens), including a carb rebuild kit. Said kit includes a new pilot air #1 jet.
Bad news: the rebuild kit must be for California-standard tuning, because it has different jet sizes. According to the crumby Clymer manual, the stock pilot air jet should be a Mikuni size 67.5. The jet in the rebuild kit is a size 70, one step up.

So, going with the half-height spacer mod (2 #4 washers) on the jet needle, and a new 50/150 pilot/main jetting (original was 52.5/147.5 IIRC, can't be sure because the wind took My old main jet as well), and the stock Mikuni size 230 (2mm) pilot air jet #2, can I get away with using this size 70 pilot air jet #1, or should I just suck it up and order a replacement size 67.5?

The bike broke down about three weeks ago, and I've been subject to Wisconsin's cruel interpretation of "spring" weather, among other B.S., stopping Me from getting any wrench time in, so I'm hoping I could just use this jet and maybe, just maybe get running again this weekend.

LANCER wrote on 05/25/19 at 12:20:52:


No on both accounts. Still have the gas tank off, bags off. Along with pulling and cleaning the carb, I'm also swapping the petcock, and was planning on doing a general "inspection" of the bike (regulator/rectifier, stator, check spark plug, anything else I could muster), as well as cleaning the poor filthy thing. Don't want to be marooned on the side of the road again, paying for a tow.

carb is mostly reassembled sitting behind Me here in My bedroom, brought it in to do some research. Sadly, for a carburetor that's been in use for at least thirty years on different machines, there's surprisingly little in the way of info or support for the Mikuni BS40SS. Doesn't even look like You can buy them anywhere, new or used.

batman wrote on 05/25/19 at 13:51:38:


Bike's a 2007.
Note that I'm not really looking to buy a whole new carb, I just thought it was odd that they don't appear to be available anywhere, and that information on them seems sparse considering how long they've been around.

I should be able to find the proper jet on ebay for a few bucks, was just hoping to save time and cash using what I've got on hand.