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Rough Idle question 08 RMZ 450

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I purcahsed a second hand 08 RMZ 450 last season. It clearly had very low hours, was bone stock and the previous owner said he did nothing maintenance wise other than air, oil and filter changes.

I rode the bike once last season and it ran fantastic, after that I stored it for the winter.

Last week I rebuilt the suspension, laced up a new front wheel and adjusted the valve clearances.

The bike started after a few kicks and I let it idle for 3 minutes as per the manual when doing an oil level check. While idling the bike would have a nice idle and sound great but every now and then the idle would drop a bit and the engine would become more noisy and after a few seconds of that it would go back to normal. I adjusted the air scew a tiny bit but it seemed like it was continuing to do this regardless of the rpm. This continued the whole three minutes.

When riding the bike sounds and runs well, the idle just makes me nervous.

I'm new to fuel injection and not sure if this is normal or not.

Any ideas or suggestions? Thanks!

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Did you drain the fuel? 

 

Possibly a semi clogged injector. It is not normal.

 

Where is your idle set? The RMZ likes a semi fast idle.

Edited by BDubb106

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What air screw are you talking about?

 

My 08 would idle down and sound strange sometimes when it wasn't completely warmed up, it did the same thing when I would almost kill the motor riding it.  The only thing that I can think of is that it idles down so far that the auto decomp. kicks in - and that's the noise that you hear.  

 

I would make sure you have fresh gas, and turn the idle up a little bit.

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by air screw I was meant the knob on the manifold that pulls out for cold start and rotates for idle control (at least I assume thats what it's for) 

 

 

I did drain the fuel and put in some fresh stuff...91 octane, no ethanol (bike was never run on race fuel) 

 

I will certainly try turning idle up higher and see if it continues before doing anything drastic. Is there a baseline setting for this?

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Around 1850 is ballpark from everything I have gathered. Mine is set at 1800 and it idles perfectly and does not flame out like some riders report.

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