please help with my pyle of yz!


7 replies to this topic
  • macoroniman2004

Posted July 23, 2014 - 05:51 PM

#1

the bike is a 2004 yz450f.....here we go a few weeks ago my bike started being hard to start warm......first clue valves ..the clearances were right on...but upon further inspection sure enough the valve faces and seats were whipped so i had the seats r cut and put stainless valves in with the heavier springs and bases and keepers....got er all back togther and ran perfect for about ten rides or so at about an hour or two each so to be safe maybe 25 hours.....25 easy hours i never take it past 3/4 throttle and always change oil and filters as th book says....all of a sudden yesterday as i pullled back in my driveway it stalled....while riding i was fiddling with my pilot screw and idle trying to fine tune it...needless to say i kicked and kicked and kicked until i threw a fit and cussed it out lol.....got home from work today and kicked some more plus put fresh plug in.....still no results .....i reset the pilot to where it was to begin with and no results so for the heck of it i pulled the hot start and kicked few more times .. it finally started up but WILL NOT stay running unless i have the hot start pulled as soon as i release it it dies...i removed the seat and when it is running i can here a faint chirping sound from the air filter...is this normal?.....and tomorrow i plan to do some investigating.....but does this seem like another valve issue or a carb issue??? this is my first yamaha and was fairly impressed with it until now in wich my whole leg hurts and there is a hole in my shoe from kicking...please some one point me in any helpful direction before i say screw it and my garbage man gets a sweet bonus i have alot invested in it but the way its going thats where its heading ....cause if it wont run then its no use to me at this point im about to cut my losses and go back to a honda...thanks in advance to any of the yamabeleivers

  • seacraft69

Posted July 23, 2014 - 06:09 PM

#2

The chirping sound is normal for an fcr. I believe the hot start lets more air in. I would say its probably carb related.

  • macoroniman2004

Posted July 23, 2014 - 06:21 PM

#3

kinda my thoughts but my re check clearances for like the 20th time while im at it i thought hondas were finicky lol...also can you possibly give a base setting for my pilot screw to my knowledge it has factory jetting....also im baffled as why it would just all of a sudden do this even after running flawless with the same settings...

  • G-BRO

Posted July 23, 2014 - 08:28 PM

#4

Gray is really good at YZ troubleshoots. He may chime in later.

In general, if you have to leave the hot start pulled for the bike to run it is an indication that the combustion mixture is too rich. Pulling the hot start allows more air into the mixture.

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  • grayracer513

Posted July 23, 2014 - 08:36 PM

#5

Sounds like the carb is flooding, or a jet fell out, something like that.  Have a look at the vacuum release plate on the slide, too.  Could be cracked or have a missing corner.  Might check the cam timing while you're at it.



  • macoroniman2004

Posted July 24, 2014 - 06:16 AM

#6

cool thanks guys all f the above are all ideas  I thought just needed a conformation lol after work today I plan on starting by checking the timing and valve clearance...maybe it jumped a tooth or something... ive never had to get into one of these carbs but if the valves are still good that will be my next step also still kind of baffled as why it just all of a sudden started this but ill check it all out and let you guys know what I find hopefully something...very frustrated lol



  • macoroniman2004

Posted July 24, 2014 - 03:30 PM

#7

so heres an update came home and checked timing...dead on....valve clarances still right where i left them...so i moved on to double checking all wiring connections ect. found nothing so finally got the nerve to tear into the carb right off the bat i noticed some blackish dust stuff in the filter side of carb....ah haa i thought so i disassembled and cleaned everything ...put back together and with a little tuning of the pilot screw she once again runs.....point being gray was right on it was flooding due to the pilot air jet being plugged by this black dust stuff.....so happy it runs now but the mystery of the dust??? thought and thought finally gave up and just enjoyed hearing it idle but decided id clean my filter while the seat was off and BAM found a tear in the seam of the filter.....not sure how it got there but couldnt have been there long as i just cleaned it a week ago.....point being like a ass i chased around alll kinds of issues when it was just a dirty carb.....thinking when i washed it maybe the soap i used made it brittle or something but no more re using filters for me its worth the 20bux to get a no toil pre oiled!! thanks again guys and happy trails untilthe next yama- crisis!

  • grayracer513

Posted July 25, 2014 - 06:35 AM

#8

Keep water away from the air filter when washing, not because it can harm the filter in any way, but because the foam filter stops water about as well as a tennis racquet.







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