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The TTR250 FAQ web pages -> TTR250 -> Repairs and maintenance -> Backfire through carb at idle
Post Info TOPIC: Backfire through carb at idle
One1


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Backfire through carb at idle
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 My 04 TTR250 backfires through the carb at idle as it's idling down from sitting still and revving it or from just idling for more than five or six seconds it nearly blows the carb off the intake boot what could be the issue? I've read many things but I'd like to know some specific to this bike to check. 

 

Stock everything. 



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TTRfan


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Other than the backfiring issue, does the TTR run OK? If so the valve and ignition timing are going to be OK.

I am thinking maybe one or both of the inlet valves aren't seating properly and this allows the exploding mixture on the power stroke to vent through to the carb - possibly confuse

Brian



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One1


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Well that's what I was reading was that if it backfires through the exhaust it's the carb settings but if it backfires through the carburetor it has to do with the valves and the way they are seating.

The. Ike has plenty of power. Idles higher when warm, a good bit higher.

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JOHNYBOY


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the inlet valves must be running tight. slight prop open would cause this

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One1


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Ill have to inspect this yet again when i put my new head gasket on i ordered. Its here, just didnt want to do he job. Lol. The old head gasket is fine, but i ordered one that wasnt stacked metal to try out. I inspected the head when i unstuck the rings and cleaned the valve surfaces, but didnt have a valve lapper at the time so i cleaned the seats and popped it back on the bike. It "looked" good, but who knows.

I found the rear brake dragging when riding yesterday so i pulled it apart and found carnage. Ive ordered mostly everything aside of the brake assembly itself to rebuild it. Lol. Should be here in a day or so and thatll keep me busy. 

 

F6F7C931-C82B-4FC3-8DBB-51DDC8C375A5.jpg



-- Edited by One1 on Thursday 23rd of March 2017 05:44:58 AM

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One1


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So back to the backfiring issue. Heres what my brand new plug looks like after 25 mins of use. 

 

FCEECA39-D0E0-486F-A689-F128A758F2B0.jpg



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