Heavy Breathing?

Hi Folks,

First I'd like to say hello as a newbie to both the XR, enduro bikes and this site.

I just bought a 1994 XR600R today - my first big single bike and overall I'm pretty pleased with myself :thumbsup:

I'm concerned that the crankcase breather seems to be breathing a little heavily: when the bike is idling there is quite a strong pulse of air coming from the crank breather pipe. I'd really like to know if this is normal or if it shows signs of bore wear (compression leaking past the rings?).

Thanks for all and any advice you can offer,


Mine blows out a bit too. Don't really know if it's normal or not. :devil: Mine starts right up if I follow the drill, has plenty of power and doesn't use any oil. Welcome to the site. :thumbsup:

Can't answer the breathing ? :devil:

But welcome aboard TT :thumbsup:


Thanks for the welcomes. I guess I'll just ride it and see how far I get. I'm sooo looking forward to next weekend....

Cheers & beers,


I would think it's pretty normal, when that piston moves up and down every stroke it displaces 598cc of air so that much air has to go in and out of the crank case every stoke. Although I've never noticed on my 87 xr600. David

Ya... the huffing thing is normal... the OE factory manual discusses ways to be sure that the hoses are routed properly to ensure that the outdoors don't enter into the crankcase.

L8R :thumbsup:

Thanks for putting my mind at rest on that one - can't wait for the weekend to come around.

Check out the K&N crankcase filter it works great and looks sano. :thumbsup:

You do know that heavy breathing draws masquitos? Might be a good idea to keep a safe distance from you if riding with you. :thumbsup::devil:

The wobbly way I ride, another country could be considered the safest distance :thumbsup:

Hey there from UK, That huffing thing is normal dude. When the piston goes down on it's stroke, it's pressurizing the crankcase and it is expelled through the breather. A friend of mine has an '87 XR600 and it does that same thing, not a problem. Just make sure that hose never gets pinched.

And have fun riding your newly aquired XR600R!!!!!


'00 XR650R

'04 KX500

The hose the comes out of the crank case should hit a "t" with one hose going down, and the other going up, I believe the hose on the bottom is kind of crimped to prevent water from going up it and let oil out, I think the up branch goes to the air box to suck fairly clean air in. Where are you seeing the puffing? I've never noticed it on mine. David


Now I've thought more about it the original question was probably a dumb one - I've only had multi cylinder machines before where the down strokes of one cylinder would be offset by the up strokes of another, thereby equalising crankcase pressure.

On a single cylinder there is always going to be crankcase pressure.

roosterk0031: I never saw any puffing - just felt the pressure coming from the crankcase breather on my hand as I was checking the bike out. I now know that it's nothing I should have been concerned about.

Thanks to everyone for the sensible and accurate replies.


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