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air/fuel mixture screw on a1985 Yamaha fz250 inline 4?
I have a 1985 Yamaha(Genises) fz250cc dohc 16 valve inline 4 cyl.,50 plus hp at 16,000 rpm the carbs have never had the air/fuel mixture screw opened so the adjustment can be done. I need to know the location of the adjustment screw so i can drill it out to do the adjustment to get my fuel mileage from about 12 klm a lit to near 50 as the factory says it will get, I will be happy to get 35 or 40 but not 12.please don't say to get a manual for it as i have tried to locate and never found.The bike is in Philippines and was only made for Japan and never was to leave there.It's fun and lots of power for a small engine but wow the cost to play is getting to much to handle,At high RPM it runs great but over loads the engine at idle,plugs after running hard is a nice color of tan but at low speeds they get black from to much fuel.Please can anyone help for the location of the air/fuel screw?
Please know what you are talking about before you try to ,make remarks. That screw makes the engine either run lean or rich along with jets and other things inside the carb.Thanks to you Inoperative,I will check out the carbs.I never thought to even try looking at the under side of them most are located on the side.
2 Answers
- A-TwoLv 78 years agoFavorite Answer
directly underneath the main air orifice (32-40mm) at the front (nearest the engine) in front of the fuel bowls. only reachable from below.
you will either need a trick screwdriver or to take off the carburetors.
It is a very fragile brass screw so make sure you have a good fitting screwdriver. Expect to screw it in gently and unscrew it to 1.5-2 turns.
- NomaddLv 78 years ago
That screw is only for idle and has nothing to do with mileage. If your mileage is that bad, you have a serious problem, not an off mixture. Probably gas overflowing the float bowl. The carburetor needs to be disassembled, cleaned right and the float bowl level adjusted correctly.
