Rough running yamaha v-max but very inermittent problem gettig wo

Hi Roderick:
I'm not familiar with your engine configuration, but on some of the older bikes, vibration eventually can cause a wire to break in the coil. When the engine is cold, the wires make contact and it runs, but as soon as it gets hot, the connection is broken or compromised and the spark quits or drives you crazy.
Since your bike runs when cold and quits when hot, I'd be looking for electrical rather than fuel problems.
Hope this helps.

clean the carbs and fuel system etc , replace fuel and clean or replace plugs !

Hi,,,your problem is carb related,,its running rich,,,check all adjustments.

Try putting a new jet kit in the carb.

This sounds like a carburetor problem. Either bad gas, partially plugged pilot jets, carb diaphragm cracked or has a pin hole, carbs out of sync or diaphragm cap is not tight. It would be best to have a dealer check it out. However, before going to the dealer I would try one thing. Drain the float bowls on all four carbs. There is a drain plug on the bottom of each bowl. Condensation inside the gas tank can make it's way into the carb. Bikes don't run well with water in the gas. Please rate my solution. Thanks.

If your plug is dry, then there is no fuel. This can happen for two reasons: No compression - be sure to get a compression tester and ensure that there is enough compression produced by the engine to enable the engine to run. More than likely, though, there is no fuel getting to the engine. When cleaning carburetors, it is important that you use a chemical dip. Spraying carb cleaner through it is not enough. Be sure to disassemble completely: fuel float and its needle and seat, all jets, all emulsion tubes, all air cut off systems and accelerator pumps, all enrichment circuits (choke), vaccum slide and diaphragm, all air jets, and last but not least - the idle air/fuel screw. If this is the first time the carb has been taken apart you have to drill the cap to get to the screw. once everything is apart, soak all metal parts in the Berryman or equivalent chemical dip solution for at least several hours. After, run hot water, as hot as you can stand over all dipped components and blow out with compressed air. reassemble and enjoy.

Items I would test are the mass air flow sensor, MAP sensor and the actual injectors themselves (if "business" ends are fouled you will have a poor spray pattern but they will check out OK electrically) Both maf and map control fuel mixture and timing...both important to how it runs. MAF can be gently cleaned with a Q-tip and carb cleaner... if just dirty and not failed this often helps.

Gas these days ****, and standing gas sucks even more. Drain your carbs and flush out your fuel tank. good luck

Check the choke to see it is not stuck on.
Something is causing the bike to run rich as you said.
Make sure the throttle slide isn't stuck and is working ok.
Try a smaller size jet.

your pilot jets are blocked.they need cleaned or replaced.they are a #35