Hi guys. My zxr250 has developed a problem where after about 15-20 minutes of riding it will drop a cylinder and then another and then stalls and won't start for about 20mins. Then starts up and rides as if there's no issue for another few minutes. Does anyone have any idea what this problem might be caused by? Sent from my iPad using Tapatalk
Sounds like valve clearances too tight. You might also have coil packs not working right, but generally you might lose 2 cylinders at the same time. Check your air filter for blockages. Check the exhaust headers and see if any are cold or at least colder than the others. To check the valve clearances you need a set of feeler gauges, veriner calipers for tools. To set the clearances you need a shim kit, or have a spreadsheet with all your valves listed, what the clearance is, and what shim thickness shim is under each lifter. To get enough access around the engine, you generally need to remove the carbs & tank, as well as the radiator. The easy way to check if a cylinder is at top dead centre for the compression stroke, is to look at the camshaft lobes once you have the valve cover off. They will be pointing opposite each other. That cylinder will be at TDC. Once you measure the clearances, if any are out of spec, you have to correct that but removing the camshafts, taking out the lifter and replacing the shim. Shims have a number stamped on them which is their thickess, but you should also put the calipers on them to confirm, as they can wear down or have the numbers worn off. It's probably a good idea to do the cam chain at the same time, as its a trivial job if you already have it pulled apart.
Couldn't agree more, the petrol is running out. I'd presume a vacuum hose isn't plugged into the fuel tank or engine and only the main fuel hose is connected properly. the initial amount of fuel it's getting from a very slow feed can't keep up with the amount used.
When it stops, open the fuel cap and see if you can hear an inrush of air. Try riding with the fuel cap loose so it can suck in air to replace the fuel being used.
Thanks guys. I haven't pulled it apart yet but I took it for a ride today and it done the same thing. It will start right back up with the choke on, dies when I turn it off, but if I try to use the accelerator nothing happens at all, it's like it's non existent. Could this still be a vacuumed problem at the tank? Sent from my iPad using Tapatalk
check your fuel tap, they are known to fall apart or be chock full of rust, definitely sounds like a fueling issue, cheack all the vacuum lines to the fuel pump as well.. any cracks and splits in the like can cause it to lose vacuum and make the fuel pump not work,,
these bikes have a diaphragm fuel pump and it only needs slight vacuum to operate.. if it loses the slight vacuum then it will not pump fuel (they get old and tear).. If you bypass the fuel pump and run it on "pri" (prime) it should run longer BUT! it will not fix the problem nor am I saying ride it around on prime, as you will be relying on gravity feed for a fuel supply.. I am just saying to use the prime function to trouble shoot the fuel tap (petcock).
Also check to see if you are running an extra inline fuel filter. If its flowrate isn't fast enough this can happen. My zxr started running out of fuel at 100km/h it would run all day at 60. Turned out the slightly different fuel filter I installed during a service was the culprit. Changed to a steel mesh one instead of paper and it was sorted. I would check the tank breather. The vacuum hose that connect to the fuel tap and then your fuel filter if you have one.
