well my patience has paid of for my 490j it was pinging big time but now it doesn,t this what i done timing set to standed new needle, needle jet, new main jet, pilot jet, needle and seat and mixture screw theres no point trying to tune a rebuilt motor with a carbie that has 26year old internals in it, i tryed it doesn,t work for around 200 bucks you will have a near new carb. the carbie was set to standed specs found at
http://www.stadiumyamaha.com the only change i made was a 460 main form a 440, needle is on the thrd grove i use bp primium fuel motul 800 at 40;1 and pro stength octane boster 60ml to ten litres of fuel. this motor has no head mods it has dual stage bosien reeds,dg exshust i live at sea level the bike is runing great nice at crisp down low can,t keep that front wheel on the ground yz490s are a great bike like any old bike you just need spend the time to dial them in, same said with the rear end on this model i put a whitepower spring on the shock along with all new swingarm bushes and got the shock serviced and revalved and it handles good there is no need watsoever to go backwards in putting a 465rearend on or a 465 topend,moding 490 heads or running standed reeds i think thats bs
