Fuel idle mixture screw completely broken.

Hello! I recently purchased my very first.motorcycle a 1983 kz750f shaft drive . I removed the carburetor and my #3 inner right carbs fuel idle mixture screw is trashed
It looks like some tried to drill it out poorly and lost the tip of the bit in it. Will my carbs still run okay if I manage to get 3 of 4 fuel idle mixture screws replaced and set correctly? Or should I go ahead and invest in a replacement carb body? Also if I SHOULD just replace it are there other carb bodies that will plug I to my carb rack right away ? My carbs are the keihin cv34s. Thanks so much for the help!!

It's hard to say if that broken screw will cause the cylinder to misfire. Personally, I'd replace the carb body although that's easy for me to say, but know going in that it's not easy to find replacements. The 1983 carbs are different than the earlier (and more popular) '80-'81's Keihin's; there is a floatbowl vent port in the later carbs that the earlier carbs didn't have. I'm not sure if this vent is important or not, haven't studied it close enough. Anyway, I suppose you could try the carbs and see how the bike runs, and chase the carb body if they don't run well.

Oh and BTW, I'm rebuilding a set of those same carbs right now and the pilot screws are thrashed on them too. Seized pilot screws are the scourge on these old carbs.

Thank you so much! Yeah there is still one file idle screw in my number 1 carb with the screw top slot snapped that I'm going to have to try and drill out myself that I'm nervous about. And I've also got two pilot jets pretty tight in there as well that I'll be working on delicately the next couple of days I'm sure! Is there any other set of old carburetors that I could purchase to completely replace the whole carb rack that fits right in? Would the 81, 82s fit if I purchase an entire set of them instead of trading out one carb body? Thank you again!

Yes, the earlier carbs are a direct replacement. You can run BS34 Mikuni's off a GPz or L model 750/700 too. Regardless of what you get you still need to go through them all the way and fully break them down to do a proper rebuild.

Oh, and when drilling out a pilot screw, something I just finished, some LH drill bits make the job much easier. Stay centered in the screw working up from small to large bits. Hopefully, when the old screw is just a shell it will spin out.

Thank you so much again! I found a replacement body for a little over 40 bucks so I went ahead and got it. Gonna use my Moto clubs parts washer at the garage and see if a good cleaning helps un stick some of the gunk and help me loosen things up! Pretty sure other tha whoever tried to change some of the settings before these carbs haven't ever been off or rebuilt since 1983 everything's pretty seized up! I appreciate all your feedback and will use your tips as well! Wish me luck!