06 450 new top end wont run

6 replies to this topic
  • OneShot2146

Posted March 09, 2010 - 09:21 AM


This is whats going on i put new piston and rings in my bike apon completion I start the bike let it warm up. The bike idles fine, no poping just smooth running if you twist the throttle normal it chokes out and dies. so i start the bike again starts fine idles fine twist the throttle very slowly and the engine picks up speed when you let off it pops alot. I thought it was a timming issue but i have checked it repeatedly. on the rotor there are three I marks im on the center one. If you have any idea please help im ready to push the bike in the corner for awhile im really lost. Ive done around 7 or 8 other 4 stroke top end and never had this happen i think im overlooking something.

  • tech857

Posted March 09, 2010 - 09:25 AM


Sounds like a lack of fuel to me is the carb clean? Good supply to the carb of fresh fuel??

  • OneShot2146

Posted March 09, 2010 - 09:37 AM


Yea that ive checked also a local shop told me the excelerator pump havent had the time to check it. you think it would make it pop like that also if it was a lack of fuel?

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  • tech857

Posted March 09, 2010 - 02:23 PM


A lack of fuel would make it pop when you let off. Did you line up the timming marks before you took it apart so you could see the correct set up? I have the manual for my yfz and it only shows one I mark but it could be different from the bike. I doubt its the excellerator pump.

  • OneShot2146

Posted March 09, 2010 - 02:30 PM


My bike has three marks ive been using the center my manual only shows the one mark. I jumped the gun and didnt look first i read the manual and it showed only one so thats what i expected.

  • grayracer513

Posted March 09, 2010 - 03:13 PM


As the flywheel turns in the forward direction, you will first see a pair of marks connected by a horizontal mark, making them appear as an "H". These are for checking ignition timing with a strobe light. The third mark following these two is TDC.

Your problem sounds much more like a dirty carb, or a carb problem. You need to clean and inspect the pilot jet, main jet, and accelerator pump operation next. Review the adjustment procedure in the manual for the pilot, and be sure your exhaust is not leaking.

  • OneShot2146

Posted March 10, 2010 - 07:02 AM


I took yesterday off from the bike im going to all sugestion about the carb thanks to everyone ill let you guys know when i clear it up

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