Dirt under the carb cap

[ShadyatBest]

I changed out my stock needle with a jd red the other day and when i cracked open the top of the carb there was a thin layer of dirt/oil stuck to the top of it on the inside. I hit it up with some carb cleaner and everything seemed to be fine before and after but i was wondering if this is nomal??

[utahboy]

ya i found the same thing on mine? seems to work still

[SCCRF450]

same thing here, my guess is because there is no fuel filter, it has to go somewhere

[JoeHonda]

There was a long thread about this quite a while ago. A guy did a test where he hooked his carb intake side to a shop vac and puffed blue powder into the air around the carb. Of course the airbox was also attached with a filter. What he saw was blue dust in the vent lines and top of the carb, same place he'd seen dirt earlier and led him to testing. There's a lot of speculation about this causing valve problems and why the manufacturer doesn't use a better sealed carb and so on. But the fix is cheap and easy, and in my opinion reasonable insurance against expensive repairs. Check out the carb vent kit for $20 at kevinscycleracing dot com. Everyone I know with an X, 7 at last count, all use this and none have had valve problems after installation. One had valve problems without when she used here 250X in Baja. Now she has the vent filters and no more valve problems even running in dusty areas around here.

[ShadyatBest]

so its believed that this dirt comes through the carb vent hose. I will look into some little filters for these and see

[tirebiter]

I've been using the Rocket in-line vent filters for awhile now, seem to do the trick.

$ 2.50 ea. at Kevins cycle racing