yfz trouble please help

[1 bad yz]

im workin on a 2006 yfz 450. the problem im having is that it wont start. i have pulled the baffel out an took the lid off the airbox. the guy who owns the bike told me that it had been jetted b4 he got it i have an 08 yfz built.... i pulled the carb bowl off an cleand an checked the jets an cleand the bowl. i also pulled the jets out an put my jets in a 175 main an a 45 pilot jet put itr all back together an tryed to start it..... got no start but did get backfiring an it trying to start i also scred the air/fule mixture screw all the way in an backed it out 2 1/2 turn an still got no start ... what am i doing wrong some one please help me thank you .....

[Drfat400ex]

Maybe an air leak in the boot or something? Sounds like it's leaning itself out but I'm really not great with carbs so that's what I can think of. If you can't see the leak just by looking for dark spots, or cracks, take the boot off, cover both ends but leave a small hole in one side, light up a cigar, cigarette, joint haha, get a big lung full and blow it into the hole, see if there's any smoke comming out.

[Tommy Warren]

hows your spark? try pumping the throttle a couple time before you hit the starter and see if it fires. if it does then your lean fo sho

[TheLane]

Also there are a few things to check on the carb, Does it run if you turn the idle screw up ( aka your starting throttle position screw). if it does there are a few things it can be. Also these things are still good to check.

Check to make sure a few things are done properly.

IE: Make sure the slide isnt upside down. the tapered end should be down.

Make sure the little rubber O-ring on the fuel air screw is on the right side (aka outside of the spring).

Make sure you soak the whole carb in carb cleaner overnight to make sure all the cast in air jets are not clogged.

Take some welding tip cleaners and poke through all the jets to make sure there is no blockage.

Beat up the guy that sold it to you.

Dont listen to Tommy Warren. :devil:

Make sure your float level is correct.

If it has a fuel accelerator pump, make sure the diaphragm is clean clear and seated properly. (this usually doesnt have an effect on idle but if it blocked it can cause problems with proper fuel circulation)

Also like stated above, make sure your spark plug is good.

BEFORE YOU DO ANY OF THIS - try and push start it, if it does start it could be electrical.

[1 bad yz]

i kno the jets are clean cuz they are new what should the float gap be set at would it be a good idea to pull the carb off the race bike an put on the 06 or would the carb from my bike be putting too much fule an drownding the spark????????

[1 bad yz]

also i was informed that the bike had a dead battery in it when purchesed an the boy would drift start it when he wanted to ride he pulled the battery out an ran it like that i also pulled the stater cover an checked the stator there was an ungodly about of black on the inside ring around the stator i wiped all that off with a rag an carb cleaner on a rag i dont think that would have anything to do with it cuz it has spark....

[mxpimp2000]

push start it or pull it behind another quad to get it started. if it starts like that then the valves need adjusted. Valves too tight it wont start no other way but to pull/push it off.

[SRH]

if it has a aftermarket cdi thats the problem, they will still have spark

but pull the plug, put it in the cap, turn the key on sometimes they will spark right away, then its definite

i picked up a used yfz cdi on ebay for $20 from muff's

[LITE]

DO A LEAK DOWN TEST TO SEE IF THE TOP END IS OK.COULD BE LOW COMPRESSION . HAS SOMEONE HAD THE CAMS OUT???

[Tommy Warren]

just spray some starting fluid in the carb and try it....if it starts than your problem is fuel.

[mxpimp2000]

He said the previous owner rode it by drift starting it. Im assuming he means pulling it or pushing it and bump starting it. If thats the case its 99% the valve lash are too tight and 99% it will be 1 of 3 intake valves if not all 3 by now

[finsteratv]

fresh gas and a new plug if its been sitting awhile also.