My friend needs Harley help.

[The Antibody]

To start off, Harley jokes won't help. Well, until we can figure this out, then go for it. He's not mechanically inclined, and I am in the toddler stages, but here we go.

He says he has oil leaking from his blowby, dripping onto his pipes when the engine is running. He says that it seems to overflow into his airbox and drip from there. I thought it sounded like he just has too much oil in it and it is spilling out of the overflow. He says no way. Any ideas.

Yes, I realize this is a Harley question, but this is the only forum I am a member of. I would like to help him.

 -Anti

[JK_Minneapolis]

...cue feeding frenzy!

[Wrencher]

How much oil is really coming out and how often?

[TheGoodGuy]

what kind of harley? model?

On my friend's harley he has only ONE carb feeding 2 cylinders (883 sportster).. and yeah its a Buddha Loves You but there is no carb flow out.. unless he is getting a blow by or something.

Like on the GS there is an tube going from the top of the carb to the airbox.. that isnt there on the harley.. the airfilter is like a clampon type.. just directly feeds into the carb's mouth.

[JamesG]

Has he traceed it to the carb itself or the breather tubes to the umm... "airbox".

I saw on American Blunder one time (waiting for a race to start) something about a valve or something in the top end of the heads that is connected to the rocker arms that opens and closes to keep the oil in the push rod tubes from squirting out under pressure from the crank case.  If one of those were bad I could see how it could be causing a leak.

Otherwise break out the matches and use the insurance money to buy a real bike.

[The Antibody]

I believe he meant the breather tubes. It's a dynaglide. (spelled right?) I don't know a thing about harleys. He said it was just drops before. Now it's progressively getting worse.

 -Anti

[KevinC]

I thought the oil blowing out was sold as a feature?

Broken piston ring, scored piston wall, or other piston/ring anomalies are the usual causes of excessive blow-by. If it isn't too full of oil, or hasn't been dropped.

Edit: Ooops, forgot valve seals can also do it. If he gets some oil smoke out the exhaust on a cold start-up, probably seals. Ohterwise, rings/cylinder wall.

[The Antibody]

I'll tell him to have it looked at. I guess it isn't a do it yourselfer for him.
Thanks,

 -Anti

[Dana]

I hate to tell you this but that is a Harley feature.

The head vent goes into the air box. Eventually the oil vapor builds up enough to form drips and then it leaks out of the airbox.

Millions of dollars have been spent on gadgets and gizzmos to stop that oil.

Harley has some little rubber seals in the head (I think they are called butterfly valves). They are supposed to let the air out but keep the oil in. They say the rubber valves get hard over time and not function as well but my Buell (Sportser Engine) puked oil from day one.

A lot of people reroute the breather lines out of the air box to a little pleated filter mounted somewhere lower on the bike. Others run the lines to a remote resevoir (catch can) that they empty every now and then. The catch can usually has a filter on it also.

Dana out.

[KevinC]

Well, if that is the problem, I think a $3 PVC valve will fix it. Harley's must pump a lot of air in and out each revolution, since both pistons are on one crank journal. It is probably this pumping that brings the oil with it.

Put a diaphram type PVC valve from the auto store (the kind that don't rattle, and will make a good seal when you try to blow air through it onne way, open the other), in the breather line. It should be put in so that air can go out, but can't come back in.

After a few hundred revs, the pumping will pull a pretty good vacuum in the engine, and that huge amount of air won't be rushing in and out. Hopefully, that will stop it from bringing the oil with it.

It may also improve the power, by eliminating most of the pumping losses. And it keeps oil in the engine other places as well.

For $3, it would be worth a try.

[yamahonkawazuki]

:mrgreen: i believe those are umbrella valves. arent hard to replace, pull off valve cover, replace. (both), usually what happens. they go so does the oil. into aircleaner, onto pipes/pantlegs :x  :mrgreen:  

[JamesG]

I would be careful with the PCV valve idea.  That seems like it is the logical easy fix, so I wonder why its not a universal fitment to HDs? Could be that it pulls TO good of a vaccuum and "sucks" in its gaskets? They aren't known for having the best seals in the world ya know...

I would as on a more HD oriented board or site.

[KevinC]

Sucker valves are pretty common on "performance" Harleys, except they have special chrome plated ones that cost $150...