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2005 wont idle, backfires on accel


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Have a 05 rmz450.It wont idle and backfires when you give it gas.After that the bike seems to run fine but seems to have a low speed problem of some sort.

What I have checked so far:

cleaned all jets

fuel screw o ring/washer and fuel screw setting

TPS setting

valve clearance

slide plate direction and oring

hot start not sticking

Any other ideas?

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when my 05 was doing this same thing it turned out to be a clogged starter jet (i think thats what the manual called it) if you already checked that then maybe check your accelerator pump spring/ diaphram? it seems like you problem is you are too lean from 0~25% throttle opening, maybe your AP isnt working properly. (dont they pretty much add extra fuel for your initial throttle opening?)

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Better to replace a clogged jet than clean it. They're really hard to get back to the original opening once a varnish forms - especially the pilot jet.

The carb sounds lean at idle and off-idle (as noted above). Besids the pilot jet being clogged/too small, or the pilot jet fuel passage being clogged (not sure if you cleaned the carb to that level of detail):

Check that the hot start plunger is seated tightly (as noted above). The bike will run lean if it isn't.

Check that the intake boots are sealed properly and not cracked; that the carb is seated in the boots properly.

You can spray some carb cleaner around the carb and boots to check for air leaks when the engine is running. When the engine smoothes out, you'll have found the leak (if you have one).

You can also disconnect the TPS and see if the problem goes away. A quick check that's *very* telling. ­čśĆ

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