When engine revs above500 rpms VOLTAGE drops bike has been laid down will not charge batery bike can be pushed started and runs good but wont start with starter after sitting for day . Ihave changed the battery when fully charged runs fine but will have to push start it the next day

One explanation for this would be that your charging system is faulty. It is possible that the OLD battery was ok, but was not getting charged by the faulty charge system. You put in a new battery, that is part charged before sale and ran the battery flat because it wasn't charging. If you leave a discharged lead acid bettery for 20 minutes or so, it will pick up a little again and possibly let the bike start and run, but by the time you got home you had killed the battery completely.

All the facts fit, though I'm not promising that it is the problem.

Take the battery off and charge it with a charger. Now, put it back on the bike and run the bike (It should start) While the battery is on the bike, get a volt meter on it. It should read slightly over voltage (doesn't matter if its a 12 or 6 volt system, it will read a little over when the bike is running) when you turn the engine off, you should see the volt meter drop down to the stated battery voltage. If you get no hike with the engine running and drop as you power off, its a good sign the charging system is faulty. A similar test, start the bike, meter the battery and turn on the indicators, stop light and head light to pull as much power as you can, the battery voltage shouldn't dip, because the charge system should compensate. If it does dip, consider this a confirmation that the charging system is faulty.

I have the same bike , I bought a start monkey. an take it with me, when this happens jump like its dead it will start.

Maybe this will help. This is a common problem that I have had with my GV250. Almost the same bike mechanically by Hyosung.

If the battery is low on charge and you are lucky enough for the bike to start. As per normal when first started it revs higher because the bike is cold, this turns the alternator fast to give you the electricity you need to keep the bikes computer working properly. Bike will warm up and revs drop down, alternater not turning as fast, not as much electricity being made. Bike will either stall or rev up and down irradically to try to produce its own electricity. This will occur when the battery charge is low and bike is at low revs, for example when you slow down for traffic or you stop.

If this is your problem. To resolve it when you are out on the road, keep the revs up, twisting your throttle gently when you are going slow or stopped. Give the bike a good long run on the open road to give the battery some charge from the alternator.

Make sure your battery is maintained. If you dont use your bike for a while it will lose charge just sitting there doing nothing. Give the battery a good deep cycle charge or take the bike for a good long open road ride.

First impression was why would anyone rev their motorcycle to 9 grand in neutral? I could see if you were in gear clutch pulled and ready for a "drag" or Race Start but in neutral?

Anyway I can't hear it so if the sound is like it hits 9k and starts popping then two things either an over rev limiter which I doubtr because the engine red lines at 13,500 OR you have a set of spark plugs breaking down under load

I would say the voltage regulator is not working. Has an altenator wire been damaged?

2 things need to be done first start your bike get a can of wd40 after your bike is warm and running spray around the carb jointsall 4 of them if your engine changes rpms up or down you have a intake leak ether your carb joint gaskets or o-rings need replacing or your carb joints are old and need replacing. at this point wont hurt to have you carbs cleaned also

useing a multimeter set to d.c check your charge at the battery whith out the motor running it should read above 12 volts determine the voltage stored in the battery with the meter stil conected hit the start button if the meter shows a dramatic drop in voltage its almost certain that the battery is shot howevwer if the voltage does not drop & it wont start bump start it conect the meter still set on dc increase the revs asyou do this the voltage should climb to 13.50 if it does & maintains 13.50 to 13.65 the chargeing system can be declared ok & you only need replace the battery however if it goes above 14 volts the voltage regulator is faulty & cooking the battery so you will need to replace both

Sounds like one of two things(assuming your batery is healthy), regulator is on its way out or/and check the supply cable going into/out of the unit, also check the earth lead. Best way to check is using a multimeter, check voltage on idle should be between 13.5 &14.5 v, turn on lights it will drop momentarily before rising again. Rev the engine and voltage should start to rise again, if not regulator is suspect.good luck

I guess before I can really help you here I need to know if this is a stock bike or not. If it is a stock bike the rev limiter shut the bike down the spark to protect the engine. I find it hard to believe the bike wont start. The bike usaully runs fine again once the engine fall back into the limits of RPMS. Anyhow you might want to disconnect the batterry leads strarting with the negative first and then the psoitive and let it be disconnected for about 15 minutes. This will reset the computer unit in the bike and hopefully start communicationg with the rev limiter again. If the bike still does not start you have more problems then this.

You need a voltmeter to test with. Check your battery voltage while the bike is running. At idle you should get around 13-14v, at 4000 rpm you should get over 14. If you're getting less than 13 your charging system has a problem. Could be a bad voltage regulator.