Motorcycle Repair: VT500C bogging, adjustment screws, honda shop

Question
I am having an issue with an 85 vt500c that is bogging , with black sooty plugs , the carbs have been just cleaned by a Honda shop but had no result ,  the bike will start , idle , run ..  I can get the bike to "ride" down the street in 1 or 2nd , the issue is when you open throttle it goes burr burr burr -- no power .  We have check the choke cable to ensure it opens and closes and plungers seat correctly , clean the fuel out in tank and replaced ,  I get lots or crank power out of the battery

The Mechanic who cleaned the carbs is aware of the issue I am having and believes its fuel related.   This bike has two coils four plugs ...   all four are sooty black  and this happened almost over night ,  it ran perfect the day before and the next day no power

A few people have suggested a weak battery ,  is this possible with good cranking results , like turning over several times

The bike will rev up when you pull in the cluth and open the trottle , but not with a load on in gear on the road ...


Help  

Answer
Carbs are funny animals.

First I would check your battery with a multimeter while the bike is running. You want to eliminate the easy stuff first.

It sounds like at the very least the carbs are tuned too rich for idle. I would check the size of the idle jets and make sure the previous owner didn't "experiment" with them (I purchased a bike which has all the idle jet drilled out to be about 20 sizes bigger than stock. Bike ran aweful until I replaced them - so even if the jets say they are the right size, you really need to make sure.)

When you cleaned out the carbs did you remove all the jets, adjustment screws and o-rings? Were the o-rings replaced?

Next I would locate the idle mixture screw and adjust it to lean out the idle mixture until the spark plugs read a tan color on idle. Mixture is also controlled by float height so you want to make sure the floats are operating correctly, the float valves are not leaking or stuck open and that the float heights are set per the service manual.

Once the bike is idling clean you can look at your throttle opening problem, which may be a separate issue altogether. The carbs operate on the idle jet up to about 1/4 throttle. Its hard to say what is happening while the bike is bogging like that. The problem is when you look at the plugs the bike was idling so the plugs will tell you what's going on during idle. To find out what's going on when its bogging you need to cut the ignition when the bike is bogging and read the plugs at that point. They may be a little wet from the unburnt gas left over after you cut the ignition but the color will tell you if the mixture is too rich or too lean.