Question about Yamaha Motorcycles
My Yamaha GT80 will start with a lot of help from the choke and idles very nicely but when I speed up in 2nd gear I will be giving it gas but then it bogs out. I let it warm up then take off the choke
Your carburetors need to be cleaned. The pilot jets are at least partially plugged.
If you are comfortable doing this yourself, you need to remove the seats, fuel tank, and air induction system before you will be able to get the carbs out. Be carefull when removing the fuel tank, there is a wire harness that will need to be un plugged from it to remove it. The wire harness plug runs under the plastic tray under the seat. There are 3 plastic rivits that will need to be removed to get to the plug. The carbs come out as a pair, and can be tough to get back in the boots.
You need to remove the float bowls, remove the jets, and blow carb cleaner and compressed air through them all. The pilot jets are most likely the only culprit, but you might as well clean everything if your going to all the trouble. You should also blow carb cleaner and compressed air through all of the other passages while your at it. Make sure that you can see through the jets and there is no debris left in them. Make sure to clean the floats, needle valves, and float bowls as well.
This happens when the bike sits for long periods. The fuel we get now days has a very short shelf life before it goes bad. Fuel oxydizes over time, and it happens even faster in a small amount that is vented which is exactly as it is when its in the carburetors of a motorcycle. When fuel oxydizes and evaporates, it leaves a gummy mess behind. The pilot jets are the smallest passages that sit in the fuel, so they naturally plug first.
You can prevent this by keeping fuel stabilizer in your fuel when ever the bike will be sitting for long periods of time. Myself personally, when I store one for the winter, I like to leave the carbs empty.
Posted on Nov 26, 2008
Sounds like you need the carbs cleaned and synchronized, then the idle set once the bike warms up. May also have a cracked intake boot, or a vacuum line off.
Posted on Jun 09, 2009
ALWAYS have a fire extinguisher on hand when working on carburetors.
Remove the water trap bowl at the bottom of the petcock, (gas valve). Is there any water or trash in the bowl? Drain a cup of gas from the tank. Is there any water or trash in the cup? Dump it, clean it and re-mount it, ( not all bikes have a water trap bowl ).
Drain the carburetor. There should be a screw on the lower side of the carb float bowl. Remove the screw then replace it after the fuel drains. Turn the gas back on and wait a minute for the carb to fill with gas. Install a new stock NGK spark plug and try to start the engine. If the bike doesn't start and run properly then shut off the gas and remove the carburetor from the engine.
Remove the float bowl and clean the entire carb with a spray carb cleaner from the auto parts store. Wear protective goggles to avoid getting spray in your eyes. Spray into all the little airways and fittings in the carb. Remove the idle screw and the air screw on the outside throat of the carb and spray into the screw holes as well.
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Be sure to put these two screws back in the same hole they came out of. IMPORTANT > do not tighten these two adjusters down. Only screw these in until they LIGHTLY seat. Now turn each adjuster one and one half turns outward. Before putting the slide back in the throat of the carb, move the clip on the jet needle one notch lower. Put the rest of the carb back together, clean the air filter and install the carb. Let the float bowl fill then start the engine. This process should get you back on the road.
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Posted on Jun 13, 2009
SOURCE: not idling
The choke allows more fuel into the engine, I would say that you have dirt or bad gas stuck somewhere in your carb, so give it a good and thorough cleaning, including the pump. Also make sure your air filter is clean!
Posted on Jul 09, 2009
did you pull the float pin out and the brass housing that the pin goes in? you may have to clean that and go get some spray brake cleaner with the red straw and blow out all the ports. the reason it will idle with the choke pulled is it shuts off air flow which pulls more fuel to air. without the choke it cant get enough fuel. i would try the bowl again starting with the float and needle. but go ahead and just really clean it all the way through or you will just keep chasing it.
Posted on Jul 15, 2009
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