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Followup To fuel flow problem
Question - Hey again chris...i have set the needle at lean...i have set it at rich...i do have a air/fuel mix screw on side of carb...no matter what i try it bogs out at 5k rpms...it has me baffled...i do not have a repair manual for bike so i've been looking to others expertise with no luck so far.
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Followup To
Question - yes chris it takes it's time bogging out...and only does it when i rev above 5000 rpms...it idles fine...how do i change lean/rich mix other than clip on needle on the carb slide?I have this set to lean but it still won't rev above 5000rpm
Hi Chris.I just rebuilt a 1978 Yamaha DT 175..started up on second kick.Carb was cleaned very well.My problem is the engine idles fin but when i rev or ride it,when it gets above 5000 rpms it just bogs out...any suggestions would be apprieciated
Answer -
Hi Mike.
Check the spark plug. It will indicate if the bike is running rich, normal or lean. My guess is either valve timing is slightly off or the mixture is either too rich or too lean.
If it bogs out immediately, then check the valves first, but if it takes it's time bogging out, then it is definitely the mixture.
Good luck.
FALCON
Answer -
Hi again Mike.
Have you looked at the spark plug? That will tell you if you are running too lean or too rich.
If you have the needle set for lean, then perhaps that is where the problem lies.
Also, a dirty air filter can cause the bike to run too rich by forcing the engine to pull excess fuel to make up for the airflow that it would normally have.
As far as mixture, that is normally set at the factory. Some dirtbikes have it set to adjust with the idle or they have another screw for the mixture which is seperate from the idle. MOST carbs are set at the factory and the screws sealed up to prevent tampering. You will have to refer to your repair manual as to which applies for your bike, since I am not as intimate with dirtbikes as I am with streetbikes.
Good luck.
FALCON
AnswerHi Mike.
We are still back to not knowing if it's bogging out because it's too lean or because it's too rich. The spark plug will tell all.
If it's blackened and/or wet, then it's too rich. If it's white or the electrode is burned away, then it's too lean. Knowing which it is will be the only way to know for certain which is the correct course of action to take to fix the bike. The repairs for a lean mixture are not always the same as a rich mixture.
Also check the connection of the carb to the airbox, carb to manifold and manifold to head. If they are not sealed correctly, then the bike will never run right, no matter what other problem may occur. It could also be the cause of your problem now.
Good luck.
FALCON
