Please help. Kinda new to all this mechanical stuff.

14 replies to this topic
  • Ryder988

Posted June 08, 2011 - 10:03 AM


Just recently my bike has started having a little bogging issues and its popping when I get on the throttle and actually died on me once while I was on the throttle coming out of a corner. It's also every once in a while taking forever to start. Could my valves maybe be out of spec.what do you guys think and if that is most likely the problem how hard is it to adjust them if I was to go get a service manual.or should I just take it in to a mechanic.

  • grayracer513

Posted June 08, 2011 - 10:07 AM


We have no idea what sort of motorcycle you own, unfortunately.

  • Ryder988

Posted June 08, 2011 - 10:25 AM


oh my bad its a 08 yz450f.

  • dbritt82

Posted June 08, 2011 - 10:30 AM


Get your self a service manual and some feeler gages. its not to hard at all and why pay someone when you can gain some experience and a good peice of mind.

  • Ryder988

Posted June 08, 2011 - 10:33 AM


does it maybe sound like my valves are off from what the bike is doing then.

  • grayracer513

Posted June 08, 2011 - 10:41 AM


Not really, but they could be.

The first thing you should try is adjusting the idle mixture (pilot screw). You might also want to look into the accelerator pump timing.

Links to download a manual and to instructions regarding the idle adjustment are in the Common Threads Sticky at the top of the index page for this forum.

  • dbritt82

Posted June 08, 2011 - 10:43 AM


I would deff check your carb first and make sure its clean and your float hight is correct as well. But with little knowledge of motors get the manual it will help you alot

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  • RiderX

Posted June 08, 2011 - 10:44 AM


Since it died on you coming out of a corner you might check your float level as well.

  • salemonkey

Posted June 08, 2011 - 02:03 PM


not trying to say its rider error. but i have noticed if im in to high of a gear and snap the throttle it will bog sometimes. something to take into consideration as well. but if the bike is getting harder to start. might as well start with your carb and go from there. checking the valves wouldnt be a bad idea either(just to make sure the bikes in spec). my yz 426 was hard to start. i reshimmed my valves because they were off and it was still hard to start. untill i rejetted my carb. wasnt untill i replaced all the jets in my carb till it started every first to second kick(even though i did a very good cleaning of the carb/jets before i tried this). also figuring out if it needs a few cracks of throttle before kicking it helps wonders.

with the changing weather from cold to hot now that its summer your bike could just need a slight adjustment like grayracer said and is a good place to start.

  • Yamiryder

Posted June 08, 2011 - 02:15 PM


The popping on decel is pretty normal.

  • i_wheelie_longer

Posted June 08, 2011 - 06:41 PM


The popping on decel is pretty normal.

Not exactly. Popping on decel generally means the jetting is too lean.

  • grayracer513

Posted June 08, 2011 - 07:28 PM


Not exactly. Popping on decel generally means the jetting is too lean.

That could be true if the popping is excessive, or it could mean there's an air leak in the exhaust. But a certain amount of it is indeed normal, and actually means your idle circuit is just about right. If it never pops at all, it's probably too rich.

  • yz450fcranker

Posted June 09, 2011 - 03:51 AM


an iridium spark plug will get you out of the corner in time

  • Yamiryder

Posted June 09, 2011 - 05:57 AM


Not exactly. Popping on decel generally means the jetting is too lean.

That's why I said "pretty" normal.:ride:

  • Ryder988

Posted June 09, 2011 - 07:50 AM


Thanks everyone I actually didn't start having problems til it warmed up now that I think about it but I did adjust the idle screw and took it down the street and it did seem to run a bit better but I'll be taking it out to the track saturday so well see if that adjustment took care of the problem.

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