Crankcase Breather Hose...

[Ryan Stanley]

So I recently replaced my intake with pods (have yet to adjust carbs). Just now, I took my bike into town (about 5 miles roundtrip). I smelled interesting things coming from my bike that I don't remember smelling before.

Anyway, when I got back home, before I shut off the bike, I noticed what seemed to be smoke coming from the filter at the end of the crankcase breather hose. It is somewhat cold outside, so it might have just been hot air that I saw, it's hard to say. Anyway, I smelled it, and it smelled like gas.

Is this normal?

[bikerphil]

smoke

Usually any smoke that comes out the breather is blow-by from the rings (compression leaking past). A small amount of blow-by is normal for older, high mileage engines. If it is excessive, then you may have worn rings/scarred piston walls. I'd be a little concerned if it smells like gas in the crankcase; check to see if your oil is contaminated with gas.

[Ryan Stanley]

Well, I just spent another 5 minutes or so in the garage with the bike running, smelling the crankcase breather filter and such, and the only think I accomplished is catching a bit of a buzz.

I took a sniff inside the crankcase, but wasn't sure I smelled any gas...

How would I know if I have worn rings or scarred piston walls?

[bikerphil]

To check for oil in the gas, take a small stick or such, dip into the oil thru the filler cap & try to light it. If it catches fire, you've got gas in the oil.

To check condition of pistons and rings, start with a compression test. If you have any low readings, with the throttle wide open when checking, might indicate a problem. Like I said before, a little blow-by is caused by normal engine wear, and nothing to worry about.

[Ryan Stanley]

Alright, just tried lighting a stick. Didn't seem to catch fire, just sizzled.

[bikerphil]

Well thats good, no oil in the gas. Don't be worried about a little blow-by. My old 79 Standard motor that I recently replaced had some blow-by for about 30K miles. I changed the motor not because of that, it had 2 bad bearings. If you do a search on "leakdown test", that's a more accurate way of telling you the condition your rings are in. HTH

[petejw]

join the club Ryan, mine does the same
its a good way to tell when the bikes
warmed up, itll start smoking. :-)
also a good way to impress a date
when you get to your destination
you'll both smell of oil. :-)
not much you can do other than putting the airbox
back on, replacing the rings, even rerouting the breather away
doesnt help.

how many k's has your bike got, mines up around 130,000.

[Ryan Stanley]

Well the odometer reads about 29,000. According to the previous owner, this is the actual mileage, but who knows...