Please help

1986 Yamaha maxim 700. Takes 10 minutes of cranking to actually fire, then several minutes to get it revving properly. Carbs are cleaned, rebuilt, and synced. Brand new wires, plugs, and ignition coils. It'll run with 0 throttle response, then suddenly it revs great. Then back to how it was. Also it'll just very abruptly shut itself off. Fuel seems to be going through my fuel filter just fine. Possibly valves? I'm just tired of fighting with it. I love the bike but it doesn't love me back. Please help. I'm very desperate to get this bike running and riding again.

 

This sounds like an electrical problem more than fuel. Bad connections at the spade terminals, pickup coils (gap, resistance) shorted/chaffed wiring or maybe something with the ignition module? I'd go thru those first before another round with the parts cannon.

 

How long had the bike been setting? What shape were the carbs in, have any pics you can show us.

Should not be cranking the bike for 10 minutes without some good starter cool down periods. Hate to have you burn out the starter.

Are you running the carbs from the tank? If so, do you have a way to hook up an AUX fuel sorce? That would help with some of the troubleshooting.

Just guess, but it is carb or air leak related. Check the boots to the engine for cracks, make sure all the vacuum lines are in the right sports of plugger.

Is the fuel filter clean with the current fuel going through it? Had to have contaminated fuel mess up them carbs you just cleaned.

Pull your plugs out, put them on the wires and check for good spark. Hope that the spark is more of a blue or white color. If not, clean some of the contacts on the coil wires and in the spark plug boots, that might help.

 

I actually just replaced the wiring harness and most of the components

 

As far I know if wasn't really sitting too long. The carbs weren't too bad, but the tank was pretty crusty inside. So rebuilt the carbs, petcock, and got all the rust out of the tank. New fuel filter and fuel. Still the same thing.

 

With the crusty tank you might have to start from square one again and take the carbs to the church of clean. Doesn't take much to make a mess in one of those little passages.

 

Well I did all that stuff at once and thoroughly cleaned the tank. Even did it with a bottle before trying the tank and it was the same

 

Is there an arrow on the fuel filter meaning it has to be fitted one way? I changed my wiring harness and still had to repair the odd connector they are getting old now.