Stopping oil loss through breather

[karl]

I don't use an airfilter, airbox, or a stock (or stock type) carb nor will I.

Even easier, since you do not care about contaminants entering your engine, keep the gutted valve cover, attach a hose and run
it upward. Any blowby will run back down, problem solved.

 

[Willie1]

Before small engines went to OHV they all pulled the vapors out of the crankcase valley, as did any flathead. And no, while they aren't considered "modern" engines, the system worked well for them.

Personally on any small engine I modify that will either turn higher RPM's than stock, generate more cylinder pressure, or both, I run a minimum of 2 vent tubes from the crankcase - preferably 1 on each side, outside of the counterweights - to vent the crankcase. I also run 1 from the valve cover area, retaining a baffle if possible. These lead to the sides of a catch can with a breather, which has a drain hose with a 1 way check valve letting the oil return to the block. The 2 crankcase vent lines pull vapors from the area they are generated, the valve cover vent keeps vapors circulating to keep the valvetrain lubed, the catch can separates the mist and returns the oil to the crankcase. This has worked well for me.

Here's a diagram showing what I shoot for. Copy the concept or ignore it - I get paid and sleep the same either way.

 

[Rat]

Even easier, since you do not care about contaminants entering your engine, keep the gutted valve cover, attach a hose and run
it upward. Any blowby will run back down, problem solved.

That didn't work out very well which is how I got where I am now.

taking away the stock air filter you have no way to pull out the moisture and volatile organic compounds out of the crank case oil once it heats up.

Isn't that actually what the baffle is for?
Most of the older kart engines vent to atmosphere, and the majority vent into the airbox on the intake side of the filter... I'm trying to keep oil in the case not sneeze it into the carburetor to burn it off so quite frankly it's all benign details not at all relevant to the original question.

I have a screened over short velocity stack (engine runs like trash without it) while the screen mesh is open enough that it could suck in anything smaller than a grain of sand... it's unlikely and any case I haven't found any type of filter to use that doesn't defeat the purpose of a velocity stack or doesn't suffocate the engine.

Now I must admit the engine was last tuned for just under 900ft altitude (not the 2000ft I now reside) and hasn't been ran in about a month so I'm also well aware the current tuning is now out of range and has to be done all over beginning at the pilot jet and air screws.

FYI: You can stick your ignorance about my not caring about contaminants right back up the hole it fell from.

 

[Rat]

Honda used cast in internal baffles in the crank case. Most of the unclean masses do not realize that by taking away the stock air filter you have no way to pull out the moisture and volatile organic compounds out of the crank case oil once it heats up. Thereby allowing harmful acids to build up and start eating away the bearing surfaces first and then onto the other surfaces on a microscopic level.

I had a 1970 Honda SL175 (P-twin 4speed) and that thing leaked down worst when hot... not sure I saw a baffle or any special deflectors in the case, but the vent was above the secondary transmission shaft iirc... factory vent tube was pinned down and pointed at the chain.
There was never an airbox for it, the factory filters were a factory designed pod type with washable foam covers similar to the pre-filter sock some use on their UNI's. The battery box was mounted to the frame between the filters, and the filters mounted to it.

 

[Willie1]

not sure I saw a baffle or any special deflectors in the case, but the vent was above the secondary transmission shaft iirc... factory vent tube was pinned down and pointed at the chain.

Vent was in the same location on my '82 Honda CBX - hose went from a barb on top of the crankcase up to the airbox. I never had the case split to see if it was baffled inside. There was no venting in the valve cover area. Let's see - a 1047cc inline 6 cylinder, 100+hp, 6 carbs, 24 valves, 4 cams, shaft driven clutched alternator - I gotta say it qualifies as a "modern" engine - vented from the crankcase area, not the valve cover.

Funny coincidence - I also had a 1970 Honda SL175 in the mid 70's. I bought a 3 year old one from a neighbor when I was 14. Being fairly new, I didn't have to work on it much, so I couldn't tell you much about the details, other than it was a twin cylinder with 2 carbs.

 

[Rat]

Vent was in the same location on my '82 Honda CBX - hose went from a barb on top of the crankcase up to the airbox. I never had the case split to see if it was baffled inside. There was no venting in the valve cover area. Let's see - a 1047cc inline 6 cylinder, 100+hp, 6 carbs, 24 valves, 4 cams, shaft driven clutched alternator - I gotta say it qualifies as a "modern" engine - vented from the crankcase area, not the valve cover.

Funny coincidence - I also had a 1970 Honda SL175 in the mid 70's. I bought a 3 year old one from a neighbor when I was 14. Being fairly new, I didn't have to work on it much, so I couldn't tell you much about the details, other than it was a twin cylinder with 2 carbs.

Mine was a K0 (first 6months production) the K1 was mostly visual changes as far as an documentation is concerned, but The Candy Sapphire Blue w/white Decals made it one if the most Rare of an already rare bike (3yrs total production)

I also stand corrected by my own old images, the case breather was that little spike you see almost under the cylinders in the first pic if you zoom in... which puts it above the timing chain and lower timing sprocket. I do know it dripped a little after being parked hot though.

It was 40 years old when I got it and a total mess.
I had to split the case to replace the kicker spindle because the external end was just a chewed nub barely holding back the oil at the cover seal.
I had to go through the electrical and top end because only one plug was sparking, one cylinder had pretty much no compression the other had 90psi but somehow still fired right up if bumped in second (it shouldn't have ran at all)

The battery was the wrong size bungied to the rear fender but it worked until I figured out the oe one (I'm sure having one you may recall no battery or dead battery means no start)

Due to a swissed out muffler, I put a K1 muffler (more solid construction even comparing new to new) with the original K0 shield on it.

Plugged a hole in the mag cover where the shifter was put through it in a lay over before I got it as well as pushed a couple dents out of the fuel tank. Speaking of that was the most spotless 40 year old steel gas tank that had never bean internally coated or anything I've ever seen anywhere... actually the cleanest raw steel fuel tank I've seen on anything older than 5 years up in Ny.

The only thing I did any different from the factory base was put signals on due to the OE harness being generic CB/CL/SL used and already had everything for them except controls which I went with 68 CB200 for iirc

I really regret selling it

 

[Willie1]

Mine was a K0 (first 6months production) the K1 was mostly visual changes as far as an documentation is concerned, but The Candy Sapphire Blue w/white Decals made it one if the most Rare of an already rare bike (3yrs total production)



I really regret selling it

Mine was orange with white stripes to start with. Was black with red and gold metalflake for a while. It saw a couple "rattle can renovations" one summer after a few incidents with local small town PoPo. I sold it in '76 to a farmer, who rode it for about a year, then put it in a barn and forgot about it. When I inquired about it about 10 years later he said it had been sold, but when the barn burned to the ground about 25 years later, the bike was still in it.

You mention a 4 speed - pretty sure mine was a 5 speed.

 

[Rat]

When I inquired about it about 10 years later he said it had been sold, but when the barn burned to the ground about 25 years later, the bike was still in it.

You mention a 4 speed - pretty sure mine was a 5 speed.

Thats a kick to the nuts!!!
Youre right the SL175's were only ever a 5speed... I never really pushed the Ole girl that hard. The one time I did was after wearing in a fresh clutch for about 50miles... I ended up riding a wheelie unexpectedly, about sh!t myself and had a really stupid ear to ear grin stuck on my face for a couple days.

It would be interesting to know if it was a late 70 or an early 70 the dead tells were the K0 had "175" in stickers on the side cover, and a slatted exhaust shield, where the K1 had flashy chromed emblems, and a tacky chrome cover with big round holes... the two had slightly different decals on the tank as well.

I decided new clutch, probably putting more power to the ground and I knew the final drive wasn't factory by then (turned out the rear wheel was from an RD175 and later I sourced the correct CB/CL/SL wheel for it) I got er up to near 65 (probably 55 in truth with the old mechanical mag field driven speedo) and was coming in a bit hot on a 4way stop and had preemptively double downed from 5th while riding the front brake and pumping the rear. I got close enough to see that I could safely blow the sign (blacktop middle of nowhere almost never any cross traffic to stop for anyway) so I dropped to second and started to let the clutch out and she wound the tach up to 11k (agin figured it to read higher than actual) so I kicked er up a gear cranked er up to 6k.
I dumped the clutch the nise shot up... I rode that unexpected wheelie out belly to tank and nearly kissing the bars to not tip back and slowly let off the throttle and started to stand/lean back on the pegs to set her down soft and easy.

Litteraly the most fun I ever had on that bike wrapped up in a half second of calculated risk (Im bad at math) and maybe 10 seconds of OH-HELL-YEAH!