Rough idle, backfire issue.
 

Forgive me i am a bit new to this game but i have a 1981 Generation 1 Mazda Rx7 FA/SB- with a 12A (1.1L)engine and a standard Nikki carburettor. Everything on this car is standard. The problem is that even though it idles over, it idles over a bit rough. Is this normal? Also after accelerating it sometimes backfires. Is this normal? On all the diagrams that i look at the mixture screws are not where mine are. I have 2 screws on the drivers side, central on the carburettor and one above the other.One is large the other smaller. I need a diagram of this carb so i can distinguish what is what for adjustment.
Thanks for any help,
Dave:)

Dave, does it backfire when you let off the gas?...timing! you're alos looking at a 27 year old car thats "All original" talk to some of the guys about a Carb rebuild and replacement of some rubber vac. lines

It only does it when decelerating. I know they pop a bit but this is a definate backfire. :)

Check the plug wires. Make sure that they are on correctly, with the leading on bottom and the trailing on top. A LOT of these cars I have seen over the years have had these reversed by idiot previous owners. I just bought another one and sure as hell it was reversed on the rear rotor. Flipped em around and she idles like a kitten!

First of all, welcome to the forums. You should take as look at the FAQ page here https://www.rx7club.com/1st-generation-specific-1979-1985-18/1st-gen-rx-7-faq-page-237777/

After reading the information about first gens such as 1978-1980 is SA and 1981-1985 are FB (not FA/SB) and you have not found an answer to your carb/fuel/timing problem let us know with more details about your car and what are its specific symptoms and we can provide more help for you.

Also use the search tool found at the top and search for threads already created about similar topics you may want to research. There is most likely a lot of information already discussed in those threads.

Good luck!

Many thanks
 

Just want to say thanks for all your help. I found the problem in the carburettor. There was no check ball in the accelerator pump outlet. Fitted one and it runs great. Now i have to source an exhaust for it !!!!!!!!!

Good job, Dave. Congratulations on your success!

Racing Beat. It also sounds like you actually have an SA carburetor on it. Can you take pictures of your mixture screws and the barrell inlets? This will tell us what Series the carb is and it will help us in the future if you have any more carb issues because there are slight differences in the SA and FB carbs