wont start
 

Hi all. After rebuilding the top end and re-assembling everything I tried kicking over my bike but it will not fire, I tried this for approx 4 hrs but with no joy. There is a good spark and there is fuel but for some reason unknown to me it will not fire up. Please help?:confused:

what bike is it? might help with the answers.

its a gas gas ec300 year 2000, thamk you

You say there is fuel but is the plug getting wet, an indication the fuel is actually getting to the cylinder? If you had the carb off and the fuel drained out of the bowl, I have seen needles dry and stick in the closed position while the carb was laying on its side. Light taps with a heavy screwdriver handle on the bowl of the carb will usually unstick it. A 2nd thing to try (only if the plug is dry), lean the bike onto it's side until gas dribbles out of the overflow tubes then try it again. That will give a little extra fuel to the cylinder. Hope this helps.

I'm going to assume it was running before you rebuilt the top-end.

1) Did you install a new piston?

2) Did you orient the piston correctly (arrow pointing forward to the exhaust port)?

A piston installed backwards, on a 2-stroke, won't properly scavenge.

yes the bike was running, and yes the piston is arrow foward, the carb hasnt been touched and can still flood easily (usual ec300 there) the piston is wet, I have even poured a little down the barrel and tried from there and I tried a more explosive liquid called isopropanol wich is highly volatile but with no avail.:confused:

sorry I mean the plug is wet

I guess there's plenty of compression or you'd have noticed with all that kicking! So that would rule out the wrong size piston or broken rings etc. You got the head on ok? Those o-rings can be devils. Also check the PV is assembled correctly and it isn't doing something daft like totally obscurring the exhaust port. Is it firing at all? Is any fuel getting ignited even if not enough to start?

Things that would be on my list of suspects would be anything electrical I had disconnected or possibly dislodged. Sometimes you can get a spark in the open air but it's too weak when under compression to ignite. It should drive a spark across a 1cm or more in the open air if you create a test rig. Forget the exact distance but sure you can Google it. Also if the rebuild took a while I've often been surprised by how much fuel can go off especially in a vented plastic tank.

Another classic schoolboy error, not that I've ever done it you understand, is leaving an exhaust bung in!

If the plug isn't new, start with a new one and make sure your reeds are in good shape. On my 2000 EC300, the stator decided to fail during a complete rebuild. I had spark, but the bike would not start. With a new stator installed, it started on the 2nd kick.