[stevied645]

hi i got my bike all back together today after rebuild got it started it was fine but there was a slight knocking at idle when u kick engine and turn it by hand theres no noises that sound odd its now not starting at all and plug isnt wet at all and its getting a great spark any ideas its the weekend HELP!!!

 

[2stroke173]

sounds like it's not getting any gas...did the bike run before the rebuild? You can take the spark plug out and put several drops of gas in the cylinder to prime it. If it's not getting any gas it will start for only a second or two...

I assume that you've gone thru the basics gas ON, choke ON, Plenty of fuel in the tank...remove the fuel line and make sure gas is coming out of the tank. If it is you'll need to take the carb off and check the float level and take the jets out to make sure you can see thru them and clean them...

 

[stevied645]

ive cleaned jets nd checked carb looks ok the bike was running perfect before rebuild i had exhaust of and noticed piston was cracked ive went threw basics and i have tryed petrol down cylinder and it did start but didnt rev right at all im more concerned about that knocking could that be timing

 

[2stroke173]

so the knocking sound is noticeably different after the rebuild? i think most kx's make a slight knocking sound when there running...who did the rebuild? How long did the bike run after you got it started? When you cleaned the jets did you take them out and look thru them to make sure they where not clogged?

Only if you changed the ignition timing on the magneto side...have you checked it?

 

[stevied645]

yeah defo noticeably differant i did the rebuild myself im clued up on what im doin to a certain extent it ran for about 5 seconds and cut out i had the all the timing bit and everything off i marked it and put it on the way it came off how do you check the timing and jets are not clogged

 

[2stroke173]

2 strokes only have ignition timing on the stator behind the flywheel there are timing marks. Is this a 2stroke or 4? What model is it? Do you have a service manual?

I wouldn't try and start it again until you take the top end back off and see what's going on so you don't damage anything...sounds like something didn't get put back the right way during the rebuild

 

[stevied645]

its a 96 kx250 2 stroke yeah i have a manual on the bike the noise is only there at idle and you cant hear nothing when turning it by hand im not sure if it is that bad its my mate that says it sounds total differant

 

[2stroke173]

can you tell if the noise is coming from the cylinder area or the clutch? Since you just rebuilt it and it only ran for 5 seconds it might be a little noisier until everything gets lubricated again...

did you just do a top end? did you do anything to the exhaust valves?

 

[stevied645]

not sure at all where its coming from i did a full rebuild new bearings seal piston everything i didnt touch exhaust valves at all

 

[2stroke173]

can you check the compression? I would try and get it started again and see how it runs and if there are any unusual noises 5 seconds of running time isn't enough to tell much...just keep checking things out i would look at the intake and reeds sounds like for some reason it's not getting any fuel to the cylinder

 

[stevied645]

well i did have reeds out and cleaned them maybe there not opening properly i havent got a compression tester but it feels really good alot better than it used to anyway ill take reed block out 2morrow and check it and hopefully get it started and see the only worrying thing i forgot to mention earlier is it revved quite hard on start up (sticky throttle fixed now though)

 

[viperrsg]

WEll it sounds like your not getting gas. Did you take apart the carb? if so check the float thats its working, my KX125 had this problem because the guy i got it from thought he knew what he was doing, and bent the float a little so the carb was not filling with gas.

 

[dmstarr]

Last time I did a top end, I left a blue shop towel in the reed block. Check you air passages, from the airbox the the cylinder.