Apr 1, 2007
Sometimes My CRF wil miss fire (mostly in the last 2 or 3 gears) Its only two months or so old, so I figure the plug should be good. I looked at it and the bottom few threads are black, but I cant see why i would have to change it yet. I think there may be a little bit of dirt in the gas I had just put in.(Ive ran most of the gas threw it and plan to run it almost dry then refill it) Will a little bit of dirt hurt my engine?


Jun 13, 2005
you never want to run a bike completely dry cause all the stuff in the gas will get sucked into the carb and plug up your jets. and dirt is not good for the motor. might want to throw a new plug in there


Apr 18, 2006
ThormxKid said:
you never want to run a bike completely dry cause all the stuff in the gas will get sucked into the carb and plug up your jets.

It is not a good idea to run out of gas while running hard, but that is not the reason.

There will be three types of "stuff" that could be in the gas. Stuff that is heavier than the gas and sinks to the bottom, stuff that is lighter than the gas and floats on the top, and stuff that is in suspension in the gas.

The stuff in suspension will get fed into the carb regardless of the level in the tank.

The stuff that sits at the bottom will sit there with a full tank or when the tank is as empty as it will get. Note that water falls into this catagory.

It is possible that you could have something floating in the tank that could make it into the carb if you ran out of gas but that is rather unlikely. Unless it was VERY light it would get pretty well shook up during a normal ride and end up in suspension and then fed into the carb along with the gas.

The real reason that you don't want to run it out of gas is that it will run real lean as the gas runs out and the level in the float bowl drops. If you happen to be riding really hard when that happens the short burst of lean running could cause the engine to seize.


To me, a "mis" is when the engine is running at a constant RPM, you are not changing the throttle setting, and there are very, very short interruptions in the power.

If the improper running is the result of changing the throttle setting then I call that a "bog" or hesitation.

A mis is generally ignition related, could be the CDI, the stator, or the plug.

A bog or hesitation is generally the carburetor. It could be dirty and need cleaning but if it has basically always done it then the jetting needs to be adjusted.

Apr 1, 2007
I'll try replacing the plug, it only does it the odd time when im running at a constant rpm. It happens mostly under heavy acceleration and sorta if i let it rev too low and then crank it.
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