Well, you've discovered that the ugly old airbox has a couple of functions, it's not just a place to put the air filter. The crankcase vent hose goes to the inside of the stock air filter which provides filtered air to the crankcase and also allows blowby gases from the crankcase to be reburnt with the incoming filtered air. The stock system also had a condensation trap between the crankcase vent hose and the air filter to collect water and oil into the puke tube for removal at an oil change. Now that you've cleared all that out of there I'm sure it looks less cluttered to your eye, but you've lost a couple of important engine functions. I don't think there are any really good alternatives to work with a pod filter over the long term.

 

Ok, I also did something REALLY stupid that I'm afraid to admit to. When I saw the condensation trap and the way it was connected I thought it was a smart idea to remove it (and kinda break it) and connect a hose to the line coming out of the crank case and lead it to where the puke tube was. On a scale of 1-10, how bad did I screw up and what can I do?

 

venting the crankcase directly under the vehicle is a 40's-60's "road draft tube" google it, before the PVC valve came into automotive use to recirculate/burn crankcase gasses..
a short road draft tube can ingest water into the crankcase thus you need a high loop replacement hose..
See Image

yes you destroyed some well planned engineering, designed to evacuate crankcase gasses and separate contamination,,, and have what? 1/3 the filter surface area...

Do like the seat though I stitch my own when needed..
is that rear panel one piece or is there a second piece out of sight..

 

venting the crankcase directly under the vehicle is a 40's-60's "road draft tube" google it, before the PVC valve came into automotive use to recirculate/burn crankcase gasses..
a short road draft tube can ingest water into the crankcase thus you need a high loop replacement hose..
See Image

yes you destroyed some well planned engineering, designed to evacuate crankcase gasses and separate contamination,,, and have what? 1/3 the filter surface area...

Actually, that's pretty sick, it'd be like those old bikes that look like dogs pissing on hydrants. :lol2:
Truth be told it wasn't just for cosmetics. The filter in the air box wasn't even attached to the hose on the carburetor (the spring was missing), figure my carb was getting a whole lot of air, dirty air at that. So a pod wouldn't be anywhere near as bad as that. What about this tube on the alternator side of the carb that's not connected?

 

Just to add to what you said about the old draft tube, it's worth noting that the 360 degree twin engine of the rebel pumps a lot of air in and out of the crankcase because both pistons go up and down together. This is quite different from a large displacement car engine which has a balanced crankcase pressure due to the multi cylinders and the fact that as one piston goes up, another is going down so that there is no net crankcase air pumped by the pistons. The draft tubes just handled the blowby gases which tend to pressurize the crankcase. There is no alternating air pressure overlaid on the blowby gas.
All this is to say that a free flowing crankcase vent system is even more critical for the Rebel than for an automotive engine.

A short draft tube on the rebel will ingest a lot of airborne dust into the crankcase oil, unlike the stock system which can ingest only filtered air.

 

Just to add to what you said about the old draft tube, it's worth noting that the 360 degree twin engine of the rebel pumps a lot of air in and out of the crankcase because both pistons go up and down together. This is quite different from a large displacement car engine which has a balanced crankcase pressure due to the multi cylinders and the fact that as one piston goes up, another is going down so that there is no net crankcase air pumped by the pistons. The draft tubes just handled the blowby gases which tend to pressurize the crankcase. There is no alternating air pressure overlaid on the blowby gas.
All this is to say that a free flowing crankcase vent system is even more critical for the Rebel than for an automotive engine.

Ok, what do I do?

 

http://www.hondarebelforum.com/f28/rangers-lanesplitter-short-chop-build-58961.html

It's a long read, but somewhere in there he explained how he did his CC air vent, basically he used his center post (on a custom hard tail) installed a hose nipple about in the middle of it for his vent hose, then about an inch or two above that, he mounted a small pod filter on another nipple, and at the bottom of the center post he drilled and tapped a hole to drain out water/oil much like the puke tube.
you could accomplish the same thing with a 3/8" vacuum tee, by placing the vent tube in the middle, the filter pod on top, and the original puke tube to the bottom.

 

This system applies the pod filter so the blowby flow is reversed from the normal outside to inside flow so any gunk will build up inside where you can't see it. If it fouls and the crankcase pressurizes you will lose your oil seal on the crankshaft. Not a good design IMO.
Bear in mind the crankcase air pumping volume is more than the flow through the carb (2 pistons vs just one at a time for the carb) The more restricted the airflow the more pressure fluctuation you get.

 

If it fouls and the crankcase pressurizes you will lose your oil seal on the crankshaft. Not a good design IMO.

As common as that left side oil seal blows out, I think another design could potentially work better. Something about the OEM design apparently isn't all that reliable either, no one has been able to isolate the root cause for certain.

 

I've worked on a lot of old cars with road draft tubes. Even on a car engine, which does not have the extreme pressure fluctuations of a 360 degree twin (basically a 250cc single) they don't work very well. The oil gets dirty very fast, and sludge builds up quickly. You need to change the oil about once every thousand miles on those old cars, and the engines rarely ever reach 100,000 miles. The PVC valve was a huge improvement in crankcase ventilation. Since it was originally designed as an emissions control device, my initial reaction 40 years ago was to get rid of it, since I am not a fan of government mandated devices on motor vehicles. But I quickly discovered just how efficient it was at venting the crankcase, probably 10 times better than to old road draft tube. I still don't know why motorcycles don't use them, they just connect the crankcase breather to the airbox, which does trap liquids and keep dirt out. But it has nowhere near the vacuum of a hose connected directly to the intake manifold.

On a car with a PVC system, you can actually hold your hand over the oil filler, and feel the vacuum. The crankcase is under negative pressure most of the time, which works wonders as far as keeping it clean, which drastically increases engine life. The stock filter is also far more efficient at stopping dirt than those pod filters. If you are going to run that pod, I would at least suggest putting a filter on the crankcase vent hose. The filter also flows more air as well as dirt, so you will need bigger jets. I personally don't understand why people use these things. I have always kept the stock air filter assembly completely intact on all my bikes.

I also noticed you whacked off most of your exhaust system. That seriously reduces backpressure, and the engine was designed to run with a certain amount of backpressure. Between the pod filter and the cut up exhaust, you actually may be beyond the tuning range of the carb, making it impossible to get a proper air/fuel mixture at all engine rpms. The engineers designed it the way they did for a reason. Unless you are an engineer, and understand what your changes will do, other than look or sound different, it is better to leave it alone.

 

I also noticed you whacked off most of your exhaust system. That seriously reduces backpressure, and the engine was designed to run with a certain amount of backpressure. Between the pod filter and the cut up exhaust, you actually may be beyond the tuning range of the carb, making it impossible to get a proper air/fuel mixture at all engine rpms. The engineers designed it the way they did for a reason. Unless you are an engineer, and understand what your changes will do, other than look or sound different, it is better to leave it alone.

I bought the bike with the pipes like that, the weld job is very bad, and they're uneven on both sides, as well as holes, and not being long enough. The same guy that is building my handle bars is making an new header too. I'll have it on, at end of the project. I had planned to cut the exhaust if I bought stock anyway and these are short enough to put what I had in mind on them.

 

Actually its PCV (Positive Crankcase Vent) valve, which is a one-way/check valve letting the carb/air-filter air intake suck air out of the crankcase, but not allowing the crankcase to draw air in (or dirt). Works when you have an even number of pistons on alternating up/down strokes so that air is just moving between pistons. On a Rebel with the twin pistons in sync on up/down strokes, that wouldn't work, both pistons on an up stroke would suck the valve into the crank case.
Which is a small part of the design of the "breather chamber" on the crankcase vent tube, an additional volume of air for the crankcase to draw from / blow into, in addition to the volume of air inside the air filter, to buffer the vacuum/pressure and lessen the stresses on the seals.

 

Which is a small part of the design of the "breather chamber" on the crankcase vent tube, an additional volume of air for the crankcase to draw from / blow into, in addition to the volume of air inside the air filter, to buffer the vacuum/pressure and lessen the stresses on the seals.

Just to clarify a bit. The volume of air inside the air filter is essentially unlimited, since air can be drawn through or blown out of the porous filter with very little pressure drop. This is why the stock system is such a good design.

 

If that'd be the case, a road draft tube doesn't sound like a bad idea.
The frame as a puke tube is cool and totally doable too, but both seem solve my problem.
Mind, the OEM air filter wasn't even connected. I didn't take notice of this until recently, and have ridden it, without much issue.
The bike runs fine, I had to fiddle with the idle, but eventually got it settled without running that enricher the whole time. So, the pod filter seemed like it'd do better than the OEM filter was in that condition (not the intended condition). Plus, I do like the extra room. So now, the only thing left on the bike is a stator replacement. Problem is, the idjit I bought it from did not torque the left side cover and over tighten the screws, I'm guessing when he found the battery draining, he went to take off the cover using standard. One of the nuts is now rounded and won't fit any mm I have. So I'm stuck at that part. After that, everything else is tweaking and cosmetic.

 

The engine will run fine with no air filter at all and with nothing hooked up to the crankcase ventilation hose. The problem is that it won't run for a long time like that since it will be ingesting dust and grit through the carb, and road grit into the crankcase resulting in oil contamination and much more engine wear than you'd see on a stock bike. If longevity is not a concern, there is no need to do anything more.
Using the frame as your crankcase vent seems like a good way to rot out your frame over time by introducing acidic water vapour to the inside where you can't see it.

 

perhaps this will help

the Rebel has a parellel twin engine

 

Hmmm. Where did you get that pic? I would have said a parallel twin is the same thing as an inline twin since the cylinders are both parallel and inline. in your pic, the parallel twin is a 360 degree twin (power strokes 360 crankshaft degrees out of phase like the Rebel) and the in-line twin is a 270 degree twin.
Using that terminology, an inline 4 would be essentially 2 parallel twins on the same crankshaft. Inline is a term I associate more with 3 or more cylinders.

 

i found it on teh google

 

Your both correct.. depends on your region of origin or so it seems
https://en.wikipedia.org/wiki/Straight-twin_engine#Terminology