I really had to laugh at these posts about hard starting. Been there and done that!! Really gave the battery a few good work outs and also had the start then stop then not go for another few hours or longer.
OK here is the solution dudes, firstly tune into your 250 everytime you ride and you will see how it all comes together to put your bike out of action at starting time.
THE underlying problem is your sparkplugs, replace them immediately with the NGK CR8E or the iridium version of same.
Now notice how well you bike starts when cold, avoid using the choke unless the engine doesn't fire at all and if its showing tendencies of wanting to die in 10 degree celcius or less conditions after starting immediately use chock to make it run smoothly. Get riding asap keeping RPM under 6k until you've done a few kms. You should be able to get the choke off within the first 2 mins.
Now being in tune with your bike you will notice after 2 months or so (particularly in the colder months) each time you start it will begin to have less and less throttle response after you start it until it is fully warm. This is certain sign the plugs are getting more and more carbon on the insulators. In this situation never let the bike come to idle inside the first 2 mins of running as you will never restart it once it stops.
NOW how to prevent plug fouling, when you notice the starting getting increasingly dodgy its time for a some full throttle riding. You need to properly cain the bike (redline in each gear and then flat in top) for about 4kms, this will have a major effect on cleaning plug insulators and you will find the cold starting will again improve.
The second way to prevent plug fouling is to add 30ml of acetone to your fuel after you refuel the bike each time. Adding acetone will give you amazingly smooth running and NO plug fouling at all anytime. The hassle is actually adding it, you gotta get some from hardware store and do it at home. 1 liter will last you almost forever. Another thing always use the best quality fuel like highest octane, 98 is what I use in conjunction with acetone for trouble free running.
Following this will give you years of trouble free starting from your 250 Zook. I would still change the plugs every 6 months.
One thing I strongly recommend, never leave your bike idling on the sidestand, start and ride away almost immediately but at very conservative RPM ie less than 6000rpm, this gets plenty of oil flowing up into the valve gear and also gets the water heating up a little more quickly which is needed so the correct eng temp is reached to prevent long term plug fouling.
Topic: Starting Problems (Read 4950 times)