Trying to adjust the idle speed. running at 1500 instead of 1250 rpm

idle speed for most modern cars is 950 rpm. Instead of guessing what the problem is try running the fault codes to find which sensor is causing the problem

Chech idle adjustment screw, and spark plug gap.

I've seen from 500 to 1500 RPM in all the manuals I've been through, depending on the year and application (truck/car). In personal experience, 650-800 RPM is acceptable warm operation range. This will also depend on elevation. Will go up to 1200-1500 RPM for cold starting. I live at about 2000ft and my '86 Pickup 22RE idles at 725-750 like a top after about a 3-4 min warm up @ 1250 RPM if it's cold (<45ish).

fast idle speed screw, works off the fast idle cam which the choke adjustment sets, it works together by linkages. This is the raised idle speed setting you need to keep a cold engine running. First you set the idle speed by the idle speed screw with engine at normal operating temperature. Then you set the linkage up so the cam is on a raised step, throttle will be held on that raised step. then you can turn the idle speed screw to get idle at about 1500-1800 rpm. Now when you start engine cold, choke will set the fast idle cam on that raised step- when engine starts and runs it should be running at your fast idle setting. That's how it supposed to work, you just have to get everything adjusted right. I hate carburetors, they never stay adjusted right. Considering their complexity and small mechanical parts, no wonder.

turn the cable adjuster back to its original position ie between 600-700 rpm look to the left hand side of the carbs you will see a large adjusting screw on a metal bracket whilst engine is running turn inwards towards rear wheel until between 1000 - 1500 rpm remember to warm engine first as rpm will rise if idle is set with a cold engine as the engine warms up when riding

you dont,the aircon needs power to run so the computer is telling the engine to tick over at a no vibration speed,if it ticked over at the lower (400)revs,the whole car would shake.....

Have you adjusted your idle speed adjustment knob in the gas cap housing. Idle speed should be 800 +/- 80 rpm If the idle speed cannot be adjusted there then you either have the throttle linkage binding or there is something preventing the venturi butterfly from closing. Something may have dropped into your carburetor and is wedged in there.

ironmike_926 wrote: no it should be anywhere from 600 to 900

Absolute rubbish!! The idle speed should be between 1250 and 1350 rpm. If the engine is cold, the EFi will raise the idle speed temporarily to about 1600 rpm until it warms up (usually within 5 to 10 minutes at a standstill).

Your idle speed of 1120 to 1200 rpm is absolutely fine. However, if it drops any lower, you can raise the rpm by playing with the idle speed adjuster screw located on the gear-side under the fuel tank (can be seen without having to remove the fuel tank). Turn clockwise to increase rpm. You will find details on how to do this by selecting your manual from this link:

http://www.yamaha-motor.co.uk/community/service/manuals.jsp

WARNING: if the idle rpm continues to drop, you may have a more serious issue with the valve clearances, air-filter, or spark plugs. Consult a technical book (such as Haynes), or take it to your local Yamaha dealer to get it serviced.

check idle speed control make your throttle valves not stuck.check for vacuum leak around the throttle body area look for broke gasket.

there is a white plastic knob on the vsv /firewall twist that out or in to adjust with ac on car running ?