2-stroke Honda CR250 fouling plugs

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6/9/2018 1:01 PM

I have a 2007 CR250 with the JD jetting kit.
The bike runs awesome. Its crisp, fast and has no flat spots.
I have been riding it this way for 3 years and it has never fouled a plug.

I have started with FMX and today i cut grab holes in my air filter box / side number plates.
When i started it and let it warm, it died. Checked the plug and it was very wet and dark.
Its obviously running rich. since its a big hole in the air filter box, it gets more air than before.
Im 100% thats the problem. Some carburator tuning is needed and i need some help to be guided in the right direction.
Im thinking some adjustments is needed on the air screw. Going for a smaller main jet maybe?
Some help is Appreciated


6/9/2018 3:25 PM

If anything the extra holes would create a bit leaner condition if the original air box was reducing air flow and thus does not match up with being rich all of a sudden.

I would suggest that you check the float level and float needle seating.
How old is the top end? How many hours?
What is your compression reading?

Paw Paw


6/10/2018 11:12 AM

^^Good info above..

Also check to see if the crank side seal went bad. That would cause a rich cond. & foul plugs.


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