need help please

12 replies to this topic
  • whiteYZ

Posted May 27, 2007 - 02:58 PM


well last night I got my bike ready to go riding today. Changed the airfilter, changed oil, oil filter, put in magnetic drain bolt, tightened chain, checked spokes etc., and swapped the 168 main for a 165 since I am pretty much seeing a constant 80 degrees here now. I am also about 1000ft above sea level. Before I changed jets I could always get this thing to start on the first kick when cold with a couple twists of the throttle and a smooth kick. Now to get it to start I have to give it a tiny bit of throttle while kicking it over. Why would changing the main jets make it harder to start??? It is an 07 and current engine mods are zipty carb mod, full dr .d exhaust, and boyesen quickshot. I was running 168 main 48 pilot and fuel screw at about 2 turns out. Figured I would switch mains and see how it felt. Anyone have any ideas on the sudden hard starting?

  • whiteYZ

Posted May 28, 2007 - 05:09 AM


also another strange thing is that my hour meter went all goofy and now quit working all together.

  • whiteYZ

Posted May 29, 2007 - 04:30 PM


any ideas?

  • bigred455

Posted June 01, 2007 - 04:34 PM


The main has nothing to do with it(harder starting). No blips of throttle at all in warmer weather,when starting cold.Valve clearances OK? Get away from the 48 pilot WITH THE 07,45 or 42,more like a 42. I am on a 40 with my 07 I am not running pump,but the fuel I am running makes it just a tad richer. I told everyone before, a 48 pilot is too rich for the 07 in warmer climates and yes even on pump fuel.It has been very humid here in Jersey,I am sure PA is the same.I am going to tower city tomorrow,by any chance are you going?

  • whiteYZ

Posted June 02, 2007 - 02:39 PM


I prolly will switch to the 45 I was just getting flames with the 45 during the winter in the first crack of the throttle and was told this was dues to a lean condition on the pilot jet so I upped to a 48.

  • bigbluerider4life

Posted June 02, 2007 - 06:59 PM


because you changed the oil...i find that if i dont start my 250f immediately after refilling it then it wont circulate and takes forver to start

if your problem is continueing after you get it refired, im stumped :thumbsup:

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • kyle450rider

Posted June 02, 2007 - 09:30 PM


How many hours you got on the bike?I had to do a valve adjustment on my 2007 with 12 hours on it now.

  • whiteYZ

Posted June 03, 2007 - 06:12 AM


right around 12. I am gonna get a feeler gauge today and check them and see what I come up with

  • kyle450rider

Posted June 03, 2007 - 07:16 AM


remember that yamaha runs them on the tight side according to some of the experts on this site.All mine were tight beyond spec.

  • whiteYZ

Posted June 03, 2007 - 03:28 PM


ok changed back to a 45 pilot with fuel screw at 1 1/2 turns out right now. When starting cold I have to give it alittle gas while kicking it over to start. After its warm it starts right up first kick everytime. I am gonna check my valves tomorrow when I get a feeler gauge.

  • whiteYZ

Posted June 05, 2007 - 04:48 PM


well checked the valves. The intake were in spec the exhaust were alittle on the tight side but not bad. Still gotta give it alittle gas while kicking it over to start it while cold. I have no idea what is going on. I dont know what happened while changing mains and cleaning filter etc that made this thing start like this . Not sure what to do.

  • motox100

Posted June 05, 2007 - 06:33 PM


In you're original post you said you changed the airfilter along with everything else . Did you happen to of just oiled it too? That will make it tough to start.

  • nap__kxf

Posted June 05, 2007 - 06:54 PM


well you gassed ti before it was running right? you probably flooded the carb. =/

Related Content


yz250x vs 450 4t comparisons (preferably desert riding) needed by JakeNorthrupYZ450F

Dirt Bike   Make / Model Specific   Yamaha   Yamaha 2-Stroke
  • 9 replies

2016 YZ450 by CaptainKnobby

Dirt Bike   Dirt Bike Technical Forums   Suspension
  • Hot  59 replies

Chubby dad, looking at bikes , First trip to the orange/black forum ! by Slow_ride

Dirt Bike   Make / Model Specific   KTM   250-530 EXC/MXC/SXC/XC-W/XCR-W (4-Strokes)
  • Hot  28 replies

Should I buy this bike? help....... by Numsa Hul

Dirt Bike   General Dirt Bike Forums   What bike should I buy?
  • * * * * *
  • 10 replies

Yamaha YZ450F 2017 by Chris.GVS

Yamaha YZ450F 2017
  • * * * * *
  • 1 review
  • Last review by Tommyk_55
  • On January 15, 2017

Join Our Community!

Even if you don't want to post, registered members get access to tools that make finding & following the good stuff easier.

If you enjoyed reading about "" here in the ThumperTalk archive, you'll LOVE our community. Come join ThumperTalk today!

The views and opinions expressed on this page are strictly those of the author, and have not been reviewed or approved by ThumperTalk.