What's the hole in the cylinder for?

Hi,

Love the forum, quick simple question?

What's the hole on the right side of the cylinder for? It looks like a leak hole, and there seems to have been something seeping out of it on my '07 CRF450R. Not much, a few drops maybe, should I be concerned?

Sorry if it's a newbie question, I looked a bit in the shop manual but couldn't find it easily enough and you guys usually have the lowdown on everything,

Thanks,

Carl

Are you talking about the small hole in the head on the right side? If so, this is a drain hole for the spark plug tube. Hope this helps....

Sometimes if you power wash you bike water can get in to the spark plug hole, and it will drain out the hole on the side of the cylinder.

Cool, you guys are the best, no need to worry then, thanks!

the piston.

:thumbsup: I could not resist.

Just a quick note; Before you pull your spark plug, spray carb or parts cleaner in that hole, pull the plug wire off and spray inside where the plug is from the top too. When all is said and done when you pull the plug, you wont get dirt inside your head. It should wash out that curious hole you ask about.

Yeah, Open Class, I deserved that, LOL. That's the problem when you try to write a concise headline.

Worst thing I saw yet was on the Glock pistol forum, a guy was complaining about his butt plug falling out (there's a kind of cover that goes in the bottom of the gun), he got about ten pages of crow for that!

Make sure your spark plug is tight and the valve cover is not leaking oil into the plug well. Either of those things will cause leakage from that hole.

It freaked me out when I got my first CRF too (an 04). Somebody at the factory slathered grease allover the bike, and when I ran it for the first time, the grease around the spark plug cap melted and oozed out that little weep hole. I didn't know what it was, but it sure looked like the end of the world when this yellowish rice-grease sludge started drooling out the side of my cylinder!

Make sure your spark plug is tight and the valve cover is not leaking oil into the plug well. Either of those things will cause leakage from that hole.

I hate having leakage from a hole:banana: :thumbsup: Sorry just saw that nobody said that yet

You can spray some contact cleaner (brake cleaner or carb cleaner) in the hole after you wash it to help evaporate any water that gets in there that may cause corrosion.

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