Hi my wrf450 on tickover revs up and down even when warm , it take for ever to kick up but when warm it starts on the button , thanks sean

SOURCE: yamaha 2003 wrf 250 start

hey m8,, sounds like u have a bit **** in the carb floating arround the jets m8,, wen its warm and bein used the dirt will flow round the carb untill left overnight to settle ,,that will block the fast idle jet,, need to take the bottom of the carb off,,ie the float bowl wip out the jet that the needle sits in to,, this will have about 4 little holes threw the stem of the jet, poke a pin or needle threw them and the main jet,, untill u see light threw the holes,, clean out the float bowl,, that should sort it,,

SOURCE: 1989 tw200 yamaha won't start

G'day egdbcs . Ok.now lets see.You say good spark,so i'm presuming you are doing the old sight test.Try bending the arm on a know good sparkplug about 5-6mm,earth the plug and kick'er in the guts(crank it over)Be very carefull , high voltage danger.If there's still a good spark it's safe to say that there will also be a good spark under pressure in the combustion chamber,speaking of which you should also do a compression test,anything over 100psi should be ok. as i'm not to sure of the extent of the re-build,hopefully the valves were lapped and checked for straight and true and valve seals replaced,if you notice oil on the tip of the spark plug you could have a leaking valve seal or oil seal .Try putting a small amount of fuel directly into the combustion chamber ,tighten up the spark plug ,install the plug cap and.......Yeah ..You guessed it ..."kicker in the guts".If all the abouve are correct and true it should fire up.If it runs for 5-10 seconds then stops you've got some sort of fuel starvation problem , could be dirt in the carb,blocked idle jet ,or air passage or even the needle could have come off it's clip,believe me with an old bike like yours anything could be worn and loose inside that carby.The only other thing to consider is the timing.There may be a good spark but is it happening at the right time inside the engine???. I'll leave it all in your capable hands EGDBCS.Hope this helps to solving your worries. Chow for now......Tilleydog..

SOURCE: Hard to start when cold, low compression in kick starter

you might of burnt your pistons ring out and now they are not pressing against the edge of the cylinder

SOURCE: banshee wont rev

Usually related to TORS, specifically the safety switch in the clutch/park brake assembly. If it's defective the engine won't rev. Solution: look for a TORS removal kit.

SOURCE: My Yamaha yz250F 07 starts first kick but back

I see: you changed the plug because it was backfiring.

Does it back fire when you let OFF the throttle after revving it, or does it back fire while being revved?

If it does it when you let off then Ollie's suggeston might do it. If that doesn't do it then check for dirt in your pilot jet.

If it back fires when revved up high could be dirt in your main jet.