My yamaha 250 4-wheeler runs great but will not idle when the choke is pushed back in to run position. When choke is half way engaged it will run fine. Which screw adjustment on carb would fix this? Thanks, John

SOURCE: won't idle steadily

did it have old gas in it for any amount of time

SOURCE: yamaha timberwolf 4x4 carberator issues

Hi,

Firstly, if you are not a mechanical person you should never buy a vehicle that does not run.
However, here are some basic tests.
1. Connect a good battery.
2. Remove the spark plug.
3. Turn the motor using the starter motor or kick starter.
4. check for spark by inserting a new plug into the plug cap. (make sure the plug is grounded).

If the motor turns freely and there is spark, chances are good that the motor will run. This does not mean that the motor is in a good condition. Only with the motor running will you be able to know for sure.

You will now have to source a carb and fit it to the 4 wheeler.
Fitting the carb is not too difficult. Check that the intake manifold is not perished or torn, and remember to use the airfilter.

Enjoy the ride !

Jon

SOURCE: Yamaha TTR 250, Idling Problem

check the inlet manifold rubber has not seperated from the aluminium part of the manifold ,this is very common on the ttr 250 and will cause the exact problem you have,if it is seperated either replace it or repair it with some good quality rtv sealant avoid sillicone sealant as it is not petrol resistant and will turn to jelly.adam

Murtaza Akberali Versi

• 767 Answers
• Posted on May 12, 2009

SOURCE: 2003 yamaha wrf 250 carb problem

(1) You will need to adjust the float pin to get the correct amount of fuel in the float chamber of the carburator.
(2) You will also need to set the air-mixture screw , but before you do tht remove the spark plug and see whats the condition of it, is it black , is it brownish, or is it whitish.
If its blackish = means rich too much of fuel, if its browinsh= ok, if its whitish = its too lean.
(3) As for hesitation, check the needle at carbs piston on the accelerator cable, and blow the main jet with high pressure.
(4) Check too the spark plug gap and if its as per the manufacturers specs.

Hope this helps!

SOURCE: won't idle steadily

Check the rubber boot that joins the carby to the engine to often have seen the hose clamps over tightened therefore creating a split in the rubber letting to much air in giving the rough idle eventually you wont be able to start it at all (have a good thorough look inside an outside of boot doesnt take much)