yamaha 2001 yz 250 jetting

[mickeydora]

Hi just bought a 2001 250 yamaha with a keihin carb. It starts fine and revs fine but as soon as I push the choke closed it bogs out. Could this be one of the jets clouged or maybe a different issue? I am going to clean carb but am looking for advice first. Thanks Also is the year on the frame any where or like the honda just on a sticker on the frame 

[bradcutter]

Carb is likely too lean. Either the carb is dirty and that causes a lean condition. Does this occur at full throttle as well or only at idle? Anytime the choke helos a bike run better after it is started and warmed up (the only time the choke is necessary), it indicates a lean condition in that particular throttle range. A choke usually works one of two ways, it either "chokes" or restricts air flow, or it adds additional fuel. Both achieve the same thing, a richer fuel mixture condition to assist in starting a bike with a cold engine. Anytime outside of a cold start that the choke helps, the bike is likely lean. Hope this helps

[bradcutter]

Check your pilot jet if fhis occurs only ar idle, also your air screw could be too far in. If the choking helps it run top end, then the main jet is too leean, clogged or needle is set too low.

[mickeydora]

I am hoping it is my main jet that is dirty. New gas drain the tank and clean the carb tomorrow. Will post results. Once I close the choke the bike dies and will not rev so it has to be gas not getting through. air screw is fine 1 1/2 turns out. Was thinking it might be the TPS that the carb has but I hope not.

[kxrob]

On 7/4/2017 at 0:30 PM, mickeydora said:

Was thinking it might be the TPS that the carb has but I hope not.

if it is then unplug it and jet around it 

frame/vin number is on the head stem of the bike ( bit scary that you bought the bike with out checking the vin first )

fyi all keihin 36mm and 38mm carbs share the same parts no matter is yamaha , kawasaki , ktm , suzuki

only difference is the needle design and profile , thats why a lot of people use suzuki needles in other brands of bikes

[mickeydora]

I don't know why I would want to check the VIN number the bike had clear title and I bought it from a friend so it's not stolen. But I got it to run perfect took the carburetor apart and the power jet was partially clogged but on top of the carburetor you have the plastic hoses and one of the hoses goes from one side of the carburetor to the other on top and plugs into the carburetor. One side had come off allowing way too much air into the top of the carburetor. Plugged it back in put it all back together started 2nd kick and it purrs like a kitten. Totally stoked I only paid 900 bucks for the bike putting new plastic on it few other things like graphics one new brake rotor with a total investment of about 1250. Stoked about that