05 480 wont idle

5 replies to this topic
  • Yamaster

Posted May 14, 2007 - 08:00 PM


My 05 480 will not idle for more than 1-2 minutes. It has an athena 480 kit, drd full system, and yfz atv cams with their cam mod done (retarding the exhaust one tooth). I also have a few other things like a boysen waterpump and quickshot. I have yzed the bike by taking out the battery and starter too. I checked the valves, cam timing, and completely cleaned the carb. With the drd d-shaped header the problem was alot worse than with the stock header for reason also. I wonder if the bike just runs hotter with the big bore? Should i change to a cooler heat range plug? Any help would be great. thanks

  • Asgeir

Posted May 15, 2007 - 02:03 PM


Rejet ?

How do you like the 480 kit ? (except for the lack of idle of course)

  • StreetbikePimp

Posted May 16, 2007 - 09:36 AM


What are your jetting specs?

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  • Yamaster

Posted May 17, 2007 - 01:28 PM


i dont believe it is my jetting because i have messed with it alot. i think it is just because the bike gets hot

  • Thumper_Bloke

Posted May 17, 2007 - 01:35 PM


I have seen a bad valve guide heat up and sieze a valve. Once cool, engine would idle again. Possibly bent valve too? These seem like extreme things to check, so hopfeully it won't come to having break it down again.

  • Yamaster

Posted May 18, 2007 - 07:10 AM


The top end was just off because i just put the big bore on it. I didnt see anything wrong with the head or valves. I wonder if a cooler heat range plug may help. I just dont know what to do. Do think I may have packed the muffler too tight also?

asgier, the athena kit gave great power. The power is much better in bottom to mid, but the top end is a little weaker compared to the bottom to mid, but theres plenty of overrev. There are two downsides however. One it vibrates like no other, and it gives some crazy engine breaking.


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