I got a 92 FLSTC about a month ago. I see a lot of varied information on about where the bike breathes from. The bike was manufactured in May of 92. From reading online I see that the bike is supposed to be a bottom breather, but the heads are setup to breather from the top.

The bike had some home made breather bolts for the head. The bike seems to be breathing out of the top and bottom breathers. I can see the threaded reducers in the head. The size of home made breather bolts are 5/16-18.

I verified the breathing of the bike by putting my finger on the breather hose on the bottom and top and could feel the air coming out of the hoses and pressure was building up while I covered the hoses with my finger. There is good air flow coming out of the bottom breather hose.

I put a SE air cleaner kit on the bike and would like to ditch the head breather bolts and put solid bolts in the head breathers. There does seem to be a fair amount of oil that is coming out of the head breathers. There was a nice puddle of oil in the manifold when I had it a part last week. I do not want all of the oil being burned up in the cylinders.

My real concern about plugging up the top breather holes with solid bolts is blowing out my rocker gaskets or any other gaskets or damaging anything in general.

If the bike is setup as a bottom breather, and someone put head breather bolts in the head, oil would be coming out of those bolts due to the fact there will be some pressure in the head and the pressure/oil/mist will find its way out using the path of least resistance, IE the head breather bolts, right?

Thanks a head of time for any thoughts and advice.

 

I would still utilize the head breather and plug off the bottom case breather.... Get a external breather kit and vent to atmosphere with a filter on the end. They're pretty cheap on FleaBay....

 

'92 was a transition year.
Your bike came out as a case breather but had removable inserts to make it a head breather.

Just vent the heads to the air and all will be good.
You might need new umbrella valves in the bottom rocker box.

 

I can rig something up to have the head breathers bypass the air cleaner to vent to the atmosphere. That requires me to drill the backing plate which I was trying to avoid. I'll check out those kits on ebay.

I had the front top end apart to change the valve seals last week as one was leaking. I did not see any umbrella valves in the rocker boxes.

Thanks.

 

The lack of the umbrella seals is one of the reasons for the large amount of oil being puked out.

Curious if it has the original heads on it, or if they were swapped at a later date to a newer style. If they are OEM, and someone knocked out the plugs, I don't see why you couldn't just plug them up again. You've got breathing off the lower end.

Otherwise, do as suggested and just routed the hose under the bike. There are a number of aftermarket kits to keep the head breathers from being routed back through the carb.

 

I have a '92 and I tried letting it breathe from both the bottom and top....Don't do it. Just put the solid bolts in the heads and let it breathe from the bottom. The '92 cam chest does not support routing for the top head breathers to work properly, and that didn't change til '93. All you will have is a bunch of oil pumping out of those hollow bolts. That was my experience about 10 years ago. I run the breather line to the back of my air cleaner of the S&S with absolutely no leaks anywhere. My engine is healthy, so it works as designed and no need to dump the mist into the atmosphere. I have the repair manual for both the '92 and for the '98 with diagrams of the oiling system. When you compare the two, you would understand.

 

The guy I bought it from said he rebuilt the top end last year with new cylinders, pistons, and heads. I am not sure the front was rebuilt and who knows what he might of replaced.

When I had the head off last week, I am pretty sure the PN cast in the head ended in 84. Also, the heads are all wrinkle black, they are not edge cut like the cylinders are to be shiny.

The parts diagrams that I have looked at show a bolt to go into the head where the breather bolts would be for a 92 FLSTC. On a 93 diagram, they are labeled breather bolts and not just bolts like in the 92 diagram.

I think I am leaning towards plugging up the holes with solid bolts. It will still be breathing through the bottom once the top gets plugged.

Thanks guys.

 

I just looked on the heads and it looks like the front head is 16721-84D and the is 16720-84C. I think is a C, it was hard to tell.

 

Well I put in the solid bolts and took her for a little spin. Nothing blew up so I have that going for me. Thanks for the input everyone.