| Author | Message | ||
     Niceguyeddy |
What is the purpose of a catch-can? Why might I need one? All apologies for what is likely a foolish question. Marcus | ||
| The_italian_job |
The catch can gets all the oil coming out of the heads of the motor... | ||
| Niceguyeddy |
Thanks T. I. J. By the way, killer bikes. Marcus | ||
| Pkforbes87 |
when the pistons fall during combustion and intake strokes, positive crankcase pressure is produced. that pressure needs somewhere to go, and it goes through the breather hoses. some oil mist also comes through these hoses because of the way the motor is designed. from the factory your breather hoses are routed into the intake (i believe for EPA reasons) using a catch can means re-routing those breather hoses into a separate container so you stop burning that oily mist into your engine. a small amount of water also condenses inside the motor every time it cools, so when you install a catch can you will see a very disgusting white gooey mess collecting inside of it. that's normal and is caused by the mixture of oil, and evaporated water leaving your engine. you don't have to buy one of the high dollar catch cans, you can make your own. just make sure the breather hoses aren't restricted. they need a way to breathe. I have used something as simple as a prescription pill bottle and a plastic fuel filter | ||
| Niceguyeddy |
Would it generally be recommended to buy/fab one? What are the advantages of installing one (engine life)? Marcus | ||
| Zoedogg1 |
Check out the post down below.."My breather looks pretty cool" thread. Just a couple ideas there. You can fab one if you like, but much easier to buy in most cases. I just changed mine up a little..pictures are posted also if you havent seen the post yet. | ||
| Jeffroj |
Sorry to hijack but hopefully someone can shed some light on this so Me and NiceGuyEddy will better understand. The breather lines are routed to the airbox, where the intake vacuum draws out the splooge and oil mist and then it is burned off. But when you reroute these breather hoses to a catch can, what is creating the vacuum to help draw out the splooge from the crankcase? I was taught that, with any engine, eliminating the vacuum to draw out the splooge, you are shortening the life of the oil and ultimately the lifespan of the engine. Does the air passing the catch can filter replace the vacuum from the intake? Any thoughts? | ||
| Bombardier |
The crankcase pressure forces the oil/mist/splooge out of the hoses. | ||
| Miko_k |
I have both my vent hoses Tee'd together and I ran them into the same plastic clip, that holds my fuel overflow hose, on the inside of the left peg bracket. My trans vent is also there, all 3 hoses zip-tied together, works like a charm and lightweight and easy, no maintenance  | ||
| Bombardier |
Do you have a filter on the engine hoses? | ||
| Got_jack |
arent you worried about all the oils getting under the rear tire as u ride? | ||
| 03worc9r |
I put off buying a catch can due to the cost. After trying about 3 different approaches and several trips to home depot or lowes, I ended up buying one from American Sport Bike. I have to say I wish I got one from the start. It looks and fits PERFECT. It is worth the money for such a simple yet high quality part. | ||
| Swordsman |
Miko, did you put a breather filter on the end of your setup? That hose can also suck inward, and if you don't have a filter, there's nothing to stop it from sucking dirt and road debris into your crank case. ~SM | ||
| Teeps |
Pkforbes87 Posted on Friday, January 23, 2009 you don't have to buy one of the high dollar catch cans, you can make your own. Or, the hose can be routed out the back or other suitable location and, left without a breather or a catch can. | ||
| Moosestang |
Nothing is getting sucked in imo. I just don't see it happening. just put your hand over the end of the hose and you'll see what I mean. I believe the heads have pcv valves on them anyway and those are a one way check valve. There is no vacuum to suck, if the lines were connected after the throttle plate, then there would be vacuum when the throttle is closed. Air flowing by the hoses at full throttle might help pull a little out, but I doubt it would make much difference. Most cars have a pcv valve and a hose connecting it to the intake manifold, where there is a vacuum while the throttle plate is closed or at less than 50% throttle. | ||
| Al_lighton |
Some random thoughts on this: 1)Parallel twin and inline 4's have constant volume crankcases. Having draw on the crankcase helps evacuate the crankcase blowby gassses and enhances ring seal. Common crankpin v-twins Liek HD and Buells have both pistons going up and down at the same time and are decidedly NOT constant volume crankcases. They have LOTS of pumping action pushing out the crank gasses, along with lots of oil mist. THAT's what the catch can catches. 2) Tests that we've run shows that we can see 2-4% increases in power by not rebreathing the spent blowby gasses (already burned air, with little residual O2 content). The piston is going to draw in a certain amount of gas, the more of it that is fresh O2 rich air instead of spent blowby gas, the more power you make. However, the better condition the engine is in, the lower those gains are. In an unachievable perfect world, with perfect ring seal, there would be NO power by routing those vents out of the airbox, because there would be NO blowby gasses to dilute the intake charge. Nice round cylinders, with nicely seated rings, make less blowby gasses. 3)Once your breather lines have left the PCV valves, the HOSE should never go back uphill, or it makes a P-trap that blocks and burps. However, once you hit a suitable sump like a catch can, it's OK to go back up. Some folks do run it back uphill after the catch can, and that actually catches drain back of the "condensing" mist on the hose walls. Me, I run it down hill to the bottom of the bike where it makes the least mess on the bike. But my breather filter on the end of the line gunks up faster. 4) Theoretically, no gas goes back into the line on the upstroke. The PCV valves are one way valves. SO theoretically, no filter on the end is required. But think of it more like a diaper than a filter for the end of the line. 5) A good much of what you are going to catch in the catch can is WATER. The water and the hyrolized oil makes a brown mayonaisey substance that, over time, can clog up the works. It's not a bad idea to flush the catch can every now and again. Al | ||
| Bo_sox |
Al - you hit it on the head. Good explanation! About once a month I open the front of my catch can and blow all that goop out with brakewash (takes about 5 minutes). Not to mention opening the drain valve after each ride. Do I ever feel better knowing all that crap isn't being consumed by engine. Anyone who is considering this upgrade - you'll be satisfied - it's $ well spent! | ||
| Niceguyeddy |
Whoa, my head is spinning. I'll need to read this strand a couple of times to get a hold of it. Thanks for all of your input. Marcus | ||
| Miko_k |
No, no breather filter on my hoses. They are good 50cm long, running straight down, I don't think anything other than a bug can crawl up into the engine, and if a bug wants to do that, oh well. Just like there is no filter on the gas tank overflow hose (which actually sucks up air as your tank empties )So far very little oil has escaped from the hoses and it's far enough away on the left, so it cannot get on the rear tire. | ||
| Moosestang |
After my ride to work and back, 30 miles round trip, I emptied my catch bottle. I was dissappointed to find only water, no oil or residue. No oil coming out the breather hose either. I think I'll leave it filterless for now. | ||
| Miko_k |
As a final thought on the subject, my point of view on the catch can: The factory setup is nice and simple, weighs close to nothing, maintenance-free, except cleaning a little bit of oil @ air filter change, no smells, minimum amounts of parts. The catch can way: extra part(weight, money, work to install, frequent maintenance, constant thinking "Should I empty it?") that really does very little good at the expense of too many factors. Which is why I just ran the 2 breather hoses into a Tee and straight down, out of my sight & mind. The only thing extra that I do is wash the inside of my left peg bracket a little more when I wash the bike and that's about it. Cheers! | ||
| Froggy |
Miko_k, you did put a filter on the end of that right? | ||
| Miko_k |
No, all my 3 hoses are without filters- fuel tank vent, transmission vent, engine crankcase vent. All 3 of them end just behind the left peg, on the inside of the bracket and use the factory retainer for the fuel tank vent ( I just removed some plastic on the inside of the clip, stuck the crankcase vent in it and zip-tied the rest to that hose). | ||
| Diablobrian |
as was mentioned earlier, while theoretically the crank vents are a one way valve there is the possibility of them leaking and sucking air back into your motor. I don't want to take a chance on sucking road dirt into my motor. Seems like a big roll of the dice to me. | ||
| Moosestang |
as was mentioned earlier, while theoretically the crank vents are a one way valve there is the possibility of them leaking and sucking air back into your motor. I don't want to take a chance on sucking road dirt into my motor. Seems like a big roll of the dice to me. Unless your hoses are really, really short, I just don't see it happening. Even without the 1way valves, the amount of air being pushed out would be greater than that getting sucked in, so you would suck your dirt up to a certain point and it would go no futher, imo of course |
