History: I used to ride a lot in my younger years and took a 10 year break. I recently purchased a 2003 Ninja 500r with 1300 miles on it for $2000. The previous owner said that the bike scared him and so he never road it. It was garage stored on tire stands and he said he kept a fuel stabilizer in it. I road it home without a problem and for the first 130 miles it everything worked perfectly. Within a day or so of purchasing it, I changed the spark plugs and did and oil change.

Problem 1: The first problem started when I reached 130 miles. While riding @ about 50 mph the engine just cut out, like it ran out of gas. I managed to get it to the side safely and after abbot 5-10 mins I started back up like nothing happened. The problem persisted every time I was at or over 130 miles on the odometer. Changing the peacock valve from reserve to on, made no difference in the problem occurring however, playing with the valve after the problem happened seemed to always help get the bike started again. Doing some research, this is a very common problem but no one seems to have a solution. The problem never occurs when the tank is completely full. I know I have spark and a clean air box.

Solution for Problem 1: I decided to take apart the peacock valve and inspect it. I don’t think the gas problem is a carb related as it is unlikely that both carbs would fail at the same time and if one was getting gummed up, it would present with spitting and sputtering. The bike runs great most of the time and then just stops. I found that there is a pin in the valve that is controlled with a vacuum line from the left cylinder. The reason I think it is this pin is because the problem never happens with the tank I full. The full tank would create added positive pressure on the pin, allowing it to open more freely. As you ran low on fuel, the positive pressure would decrease, making it more difficult for the vacuum to pull the pin back. I didn’t see any visible issues with the pin when I inspected it. I cleaned the whole thing with carb cleaner and put a dab of lithium grease on the pin and the seal that’s on the end of it. I'm not sure if this will fix my problem as I haven’t put the bike through enough miles to test it for sure. Everything worked fine on my commute to work this morning.

Problem 2: Since purchasing the bike, it has boiled over twice. Yesterday was the second time it happened. The temperature gage is only reading 2/3rds hot. The first time it did it was on a cool day with a passenger, and then again yesterday where it was 90+ degrees outside.

Solution for Problem 2: I can assume with high confidence that the coolant has never been changed out. I am going to do a full flush of the system to see if it’s just bad fluid. From there I'm not sure. My initial thought is thermostat but I'm concerned that the temp gage is only ready 2/3rds. If it’s boiling over the temp gage should be at 100%.

Questions: Could the problems be related. If it’s a bad head gasket, could it cause a lack of vacuum in the cylinder that would cause the pin in peacock valve to not open? It could also cause positive pressure to backflow into the cooling system making it boil. There is no oil in the coolant and no coolant in the oil. It runs great when it’s running. It’s not burring oil or water. Any other thoughts? What am I missing?

 

Welcome to KF and your new bike. Sorry to hear about the problems.

I don't know the Ninja, but Gen 1 KLR650 bikes have had a similar issue described by problem 1. The vacuum actuated petcock starts to fail and stops flow early, at about the same miles (or gallons). From memory, a petcock rebuild kit should fix the problem. I replaced my petcock with a non-vacuum type (shut off the petcock when parking for a while).

Problem 2. My understanding is that old coolant will still cool, but it loses its corrosion protection. I'd flush everything very well, replace the thermostat and radiator cap, check fan operation (is there a fan?), and refill with fresh coolant. Checking fan operation is pretty simple on my KLX and it may be on your Ninja, too. It may boil over because of a weak cap and not even be getting that hot. Caps and thermostats are inexpensive and worth replacing on a 13-yr old bike. Do some internet searching. It's likely an inexpensive Japanese auto rad cap will fit your Ninja (I forget which model, but I learned that on this forum).

Maybe we can get one of the Ninja owners to chime in.
Good luck and ride safe.

 

hmm, old post. nice ride