Keihan carb on 87' civic

I have read that on the carburators on some of the older civics, specifically the Keihan carbs, that there is an air-fuel mixture screw that is capped so the regular joe can't screw with the mixture. Since I don't much care what the factory said about my car 19 years ago, I was wondering if anyone out there knew exactly where this was, if it even exists, etc.
Any information would be helpful, especially if someone else has trouble passing smog due to high hydrocarbons, they might be able to tweak the mixture enough for it to pass.

i believe it's on the back side of the carb. you are correct in that you have to remove the carb to get at it. i haven't actually messed with this myself i just know this from my honda service manual for my '83. the manual is at a friends place right now but i will have a closer look later to see what's involved

Thanks a lot; any help is extremely valuable to me. do you think I could make any needed adjustments without taking off all of the vaccum lines?

probably. i had a look at an ond carb today but didn't have chance to find my manual. the adjustment screw is on the rear of the carb right in the middle but i don't know which direction is rich or lean and whatever. with a short screw driver yo may be able to adjust it in place however the ne i'm looking at is a canadian non-cvcc 2 bbl carb. the 3bbl cvcc carb is a little different and i remember there being some sort of plate that had to be removed to access the screw

yeah i cant remember exactly i had my carb pulled off for a while but i think your correct about having to remove a plate

I also have a 87 civic wagon with a 1500 engine. According to my service manual you have to...
1. remove the air cleaner
2. disconnect toe vac hose to the fast idle unloader
3. Pull the throttle cable out of its bracket
4. remove the card nuts and bolt securing the the steel tubing vac manifolr
5. lift the carb clear of its studs and tile backwards to remove the idle controller braket screw ( there is a total of 3 for the bracket)
6. remove the controller bracket (thats the plate in back of the carb)
7. remove the mixture adjusting screw hole cap
8. this is when your supposed to put it back together and be able to adjust the now exposed screw for performance.
YIKES!!!

By the way my 87' also had a problem passing smog. This was after I recently had a card overhaul a couple of months before. Turned out to be a $4 vac hose under the carb that was split. Just something for you to think about.