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Lean issue

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Hey guys need some help I have an 04 yz450f and it has a lean issue in the pilot circuit. I have signed it, pressure tested cooling system, leak down test, and compression test and all passed. I replaced the intake boot, checked exhaust seals, checked oil and filters, check cked timing, replaced all seals and adjusting screw. I replaced float shut off needle, went from a 42 pilot to 60 and all in-between. I have replaced boal seal, checked needle, checked slide, and all other jets even went bigger on the main jet. I can not figure it out, it is popping, overheating and glowing the header, new plug reads lean as well as the old. Everything else is good but I can not figure this out... If you have had the same issue or know something I can check please let me know thanks guys.

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Hot start is leaking or pilot jet passage (above the jet) is partially clogged (use #15 fishing line and solvent)

 

Service the plunger and cavity (clean, polish, and anti-sieze paste)

 

Put on an aluminum cable nut and silicone the cable ends so they stop flowing water into the hot start cavity

 

http://www.dirtrider.com/features/protips/141_0707_keihin_fcr_carb_rebuild/

 

https://www.google.com/search?q=hot+start+nut&rlz=1C1CHMO_enUS529US530&oq=hot+start+nut&aqs=chrome..69i57.2287j0j7&sourceid=chrome&es_sm=122&ie=UTF-8

Edited by KRANNIE

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could try an un-lit propane torch around possible leak spots

 

valves  have clearance?

vent hoses routed and connected correctly? 

fuel flowing freely from petcock?

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Yes sir all good, I snaked out the passages after the jets last night as well as the jets and I got a little gunk out of one passage. I put a 48 in it but still overheating on idle, headed doesn't seem to glow now though I have not took the temp reading with my gun. I will put a new seal on the hot start plunger maybe it is leaking there will get back to you. Thank you guys for the info, if you have anything else I could check let me know!

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48 is too BIG!

 

You still make no mention of the fuel screw adjustment, which is the pilot circuit trim.

 

You need to completely ignore the header glowing, as your header is Ti, and will start to glow in 2 min no problem.

You cannot tune a motor visually....

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I thought so too but I adjust the screw in and out and out at 3 on a 48 jet runs decent I'm headed to get the plunger parts now maybe that is the whole issue and I can put the 42 or max 45 back in it

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Well I snaked out the passages and put a new seal on the plunger, changed out the plastic plunger screw for a pro circuit aluminum one and rtv'ed the top like you said and sure as shitt it runs like a top, it still will overheat if I'm sitting iddle but guess I have to keep moving or shut her off. Thanks guys I'll work on jetting a little but I think it's good to go

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could try an un-lit propane torch around possible leak spots

 

valves  have clearance?

vent hoses routed and connected correctly? 

fuel flowing freely from petcock?

That's a horrible idea and never recommended for a reason. Instead spray carb clean around any possible leak spots.

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Yz450f will over heat if it idles to long. It's a air cooled motor so you need air flow for it to cool. So I don't think you have any problem there. Mine does the same thing.

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