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Hi.I bought a used monster 600 before two months .The spark plugs need replacement almost every week because they go "rich" .So there is a problem!I figured that the previous owner had dynojets on the carbs but my bike has a stock air filter and stock exhaust system .So i think that the problem is on the air intake .If i keep the dynojets and the stock slip-ons and put a K&N or another racing air filter ,wiil my bike run properly? Or do i have to change slip-ons as well?I can't afford slip-ons that period.What should i do? Thanks for your help! :-/
 

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Hi Jamsfera,

Hopefully I can get you pointed in the right direction. First, are you sure the previous owner installed a Dynojet kit, and if so, is it a Stage 1 or Stage 2 kit. The Stage 1 is meant for bikes with stock air filter/box and exhuast. If this is the case, your bike should run just fine with the Stage 1 kit.

Now, things to consider. First to look at is the float height. Both floats should be at factory spec or at the spec recommended by the jet kit manufacturer. If the floats are too high a rich condition will result, too low and a lean condition will result.

Next, look at the idle mixture screw settings. I'm not too sure what the factory or jet kit settings are but the Haynes manual may have the factory specs and if you have the jet kit then you should be able to get the settings from Dynojet. If the screws are too far in, a lean condition will result and too far out will create a rich condition.

Now on to the jet needles. Stock needles are not adjustable. Jet kit needles are. The jet kit needles should have 5 clip slots at the top of the needle. The middle position is stock while moving the clip down (raising the needle) will create a rich condition. Moving the clip up will lower the needle creating a lean condition. The jet needle settings affect the midrange where most of us spend most of our time. Also check the needle jet (the tube the jet needle slides in and out of) for wear. If your bike has over 5k miles the needle jets may be worn. Over time they will become elliptical and will pass more fuel than they should, once again creating a rich condition.

If you have a jet kit installed and the main jets are too large they too will create a rich condition even though they mostly affect 3/4 to wide open throttle. Remember, all the circuits in a carburetor work in conjuntion with one another.

It's been said on this board before that the OEM filter flows as much air as an aftemarket so changing the filter may make no difference. Opening up the airbox (modifying the airbox lid) may flow more air and might possibly lean the engine out. But, if this works I feel that you're only masking the real problem, ie. carb settings.

It may be that all you really need to do is a good carb cleaning (with a shop manual at hand), making sure all of the settings are proper and that the needle jets are not worn (if they are, replace them), then reinstall and synch them.

I hope this helps and I didn't confuse you too much.
 
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