Riding too rich, now piston is brownish, fauled

Hey guys,

I run a Honda CR250 2001 - great machine!

I just found out that my air screw was ½ turn too little outwards - making the mixture to rich.

I noticed it because the bike started to leak oil out the exhaust connection points.

I also checked the plug and the piston. Plug is black/oily. Piston is darkened too. (See photo)

Now I readjusted it the air screw.

Is there any procedure to undergo, like cleaning the piston/cylinder/plug before I run it?

 

Thanks guys.

foto (1).JPG

install a fresh plug if the old one is fouling out on you.

Air screw only affects low (idle) speed operation.  You probably have other problems.

Well that actually explains it, because I have been riding a long, very low RPM trip, like idling at the time the air screw was too closed. That explains the fouling of the plug and piston.

Do you recommend using a burner on the plug, or must it be changed ? Should I clean/ polish the piston?

Hey guys,

I run a Honda CR250 2001 - great machine!

I just found out that my air screw was ½ turn too little outwards - making the mixture to rich.

I noticed it because the bike started to leak oil out the exhaust connection points.

I also checked the plug and the piston. Plug is black/oily. Piston is darkened too. (See photo)

Now I readjusted it the air screw.

Is there any procedure to undergo, like cleaning the piston/cylinder/plug before I run it?

 

Thanks guys.

your rings (and piston) are toast.massive blowby.

 

your mixture screw being a hair out only affects performance and not the longevity of engine parts(that small setting change won,t affect wear).

 

your engine has too many hours on it.

MASSIVE blow buy, NOT a jetting problem

 

You must use the 'high pressure / low temp' break in precedure with new piston/rings if you want the rings to seal.

 

If you don't do this in the first 15 minutes.....you are too late, can't fix it till the next set of rings. 

Thanks guys,

You're probably right, i have a blow by, and the piston has many hours I think from the previous owner.

But I just proved that it also was a jetting problem - after I did the air screw the piston "cleaned up" and looks almost normal. See picture:)

The plug is now dry and black.. But it should be brownish right?

Half a turn out on your air screw makes your mixture leaner, not richer. And that half turn shouldn't barely make a difference in overall richness/leaness of the motor. Your jetting is off because your motor is wore out. It needs a piston and rings!

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