Won't start without choke

SOURCE: Hard starting when cold, runs rough at idle and any steady speed.

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.

Then re-assemble

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.

SOURCE: vmax engine will not idle without the choke on.

Sounds like your carb. may be gummed up. Did you start the bike and let the carb. get stabilized fuel into it when you parked it?

SOURCE: yzf 250 wont run without the choke

Hi mikelapt
You will have a carby problem. When the choke is one, and different fuel circuit is used. When you turn off the choke, you go back to the idle circuit of the carb is used, when under throttle, main jets kick in. You probably have a blockage in one of these circuits. Strip the carb down, clean with carby cleaner, blow out all air circuits and jets with compressed air, then setup the idle mixture and tick over speed. Always work with fresh fuel, and drain off, discard any fuel older than a couple of months. It goes off, and turns to a gel  like substance that blocks up your carby. Hope this has explained your problem. Happy to talk to you more about it. A FixYa vote is a great reward for for my time taken to explain this to you. Cheers
regards robotek

SOURCE: Yamaha 06' V-star 650 idle prolbem!

Fuel filter is located near the fuel shutoff valve within three inches. It is inline between the shutoff valve and the fuel pump (towards tank).

The fuel circuit is: Tank/Fuel Pump/Fuel Filter/Fuel Shut-off Valve/Carbs.

You first step is to check for fuel delivery to the filter. Make sure the bike is cool and no iginition sources are nearby. Disconnect the inlet line at the filter and turn key on and crank engine (to trigger fuel pump.) Do not try and start at this time (choke off).

If fuel is adequate to the filter, check the filter by blowing through it, it should easily pass air. Replace filter if questionable.

Next reconnect the fuel lines and remove float bowl drain plugs in the back of the carbs (2 per carb). If with key on and cranking fuel pours out of these ports then you probably have clogged fuel jets. If not then the float bowl needles / pipes could be plugged with varnish from dried fuel. You can try spraying carb cleaner into the fuel inlet to clear the varnish and then retest. Careful not to spray carb cleaner on yourself (wrap straw with a rag).

If you have good fuel flow to the carbs and bowls you probably have varnish plugging the jets. You should remove the carbs and clean them thoroughly.

Hope this helps,

Kal

SOURCE: 82 yamaha maxim 650 engine is hard to start cold

weak mixture,dirty fuel,air leaks on induction manifolds,jets blocked,fuel tap filter chocked,float needles sticking,fuel level in carb incorrect,thottles not opening together,air leaks at exhaust pipe joints,