Vent tube Mod

[Fox]

Here's a mod suggestion for all the Chinese 4 stroke owners so you can keep your air filter clean longer.


The crankcase breather tube coming off the valve cover is usually routed to the air filter box intake where the fumes from inside the engine are drawn in to be burned in the combustion chamber to reduce emissions. It also relieves the pressure that would build up in the engine due to exhaust gasses blowing by the piston rings. All engines get blow-by on the rings. That's why the oil turns black. There is also a small amount of oil and some water vapor emitting from the breather tube due to condensation inside the engine when you start it on cold mornings. All that stuff ends up in the air filter.




Upon inspection my air filter always had an oily black residue on it that I knew was from the breather tube. The gasses were actually so hot on long rides that it partially melted my filter foam.




At first I tried disconnecting the breather tube and letting it dangle out the bottom of my scooter, and it worked well for keeping the filter clean, but the oil and water and fumes would make my back wheel filthy after a couple of rides around town.

My solution was to get 5 feet of automotive fuel line and route the vent tube all the way to the rear splash guard.

I put a good hose clamp on the valve cover end, and routed the tube up the frame and through the body plastic using a couple zip ties, and then ran it to the inside of the rear splash guard. I drilled two little holes about 3/4 inch apart just above the bottom of the splash guard on one side and zip tied the tube to the splash guard through the two holes. Then I trimmed the end so about 1/2 inch sticks out below the bottom edge and voila! The fumes all go out the back, the air filter stays clean, and since it's routed uphill above the engine I don't lose any oil now.

It tripled the time between filter cleanings.  

Vent tube routing:




Some people say to oil the filter after a cleaning but I don't. I wash it in dish soap and water and install it dry. Oiling it makes it more restrictive. I think oiling it is good if you ride off-road or live in the desert but for tooling around town it's really not necessary so to each their own on the oiling issue.  

My air filter after a few weeks riding.



 Hope this helps somebody.  


NOTE: This modification will render your scooter non-compliant with emission standards so if your scooter ever has to undergo inspection return it to the original configuration first.





 


 

[dpark76]

NOTE: This modification will render your scooter non-complient with emission standards.

Isn't this a bad thing? I'd guess that a dirty filter is better than dirty air....not to mention that everyone's perceived notions of scooters are that they are pollution plants to begin with. States, cities, and towns will then regulate them just like regular motorcycles, and the benefit of riding these cool scoots will be lost. Think California.

[Fox]

I see garbage trucks, semi trucks, city buses and school buses spewing out black clouds every time they accelerate away from a stop. Our little crankcase vents are nothing compared to that. I feel no guilt whatsoever about it but I was told to include that sentence about emissions by Sparky so I added it in.

 California already regulates them like motorcycles. They call them motor driven cycles.

http://www.dmv.ca.gov/motorcycles/motorcycles.htm

The state govt. is so broke my registration went up by 50% this year over last. 

[Scooters]

Thanks for sharing this article about vent tube mod. The first time I crawled under the rear of SS #670, I noticed the differential was damp with oil. I cleaned it up with a little brake-clean and some rags but the next time I looked, it was damp again. It looked like a small amount of differential fluid was getting to the top of the vent tube and then running down onto the top of the housing.

[Scooters]

Thanks for this information

[MidwestFlashRT]

Isnt there a reason for the way its routed to the airbox? Without vaccum whats going to pull the gases from the head now? Also isnt it for emissions aswell?

[goosestale]

NOTE: This modification will render your scooter non-compliant with emission standards so if your scooter ever has to undergo inspection return it to the original configuration first.

That is why this "Note" was included

[Fox]

Isnt there a reason for the way its routed to the airbox? Without vaccum whats going to pull the gases from the head now? Also isnt it for emissions aswell?

 What she said^

Also, the gasses are pushed out from pressure. The exhaust gas blow-by pressure pushes the gasses out. Granted some are still in there when you turn off the engine but it doesn't matter. If the tube was hooked to the airbox then there would be gasses left behind in there too. Besides that the tube is also an avenue for water vapor condensation to escape and the last thing I want to recycle through my carburetor/intake is water. Cold outside+hot inside engine=water condensation inside the engine.

 That vent tube is hooked to the air box for emissions purposes only. It spews forth oil spray, exhaust gas blow-by and water vapor. If you want that stuff in your intake/filter that's your right.

[mikienmb05]

get you a empty drink bottle make a hole in the lid and one high on the bottle itself run the hose threw the cap into the bottom wham bam cheap oil catch can you zip tie it some where i have mine where my air box use to be is doing great..

[Fox]

get you a empty drink bottle make a hole in the lid and one high on the bottle itself run the hose threw the cap into the bottom wham bam cheap oil catch can you zip tie it some where i have mine where my air box use to be is doing great..

 My mod makes it so the oil stays in the engine. No need to "catch" it.

[MidwestFlashRT]

Isnt there a reason for the way its routed to the airbox? Without vaccum whats going to pull the gases from the head now? Also isnt it for emissions aswell?

 What she said^

LOL u got me, its wierd mine has never gotten that dirty, ever since i got it it has never gotten dirty! is dat normal?

[goosestale]

My mod makes it so the oil stays in the engine. No need to "catch" it.

I was reading some of the requirements for the "Twist N'Go" and they required a catch bottle like that for the scoots on the track, to keep it clean

[mikienmb05]

been runin it like that awhile now with the ba ba lol...its got maybe a sip in it wouldnt wet your mouth but when it was in the air box seemed to make a mess..duno hey whatever works

[mikienmb05]

hell get a fitting and a small pressure release and run it back to where the dipstick gos in lol lol like a small bov type deal..turbo oil resuclation pshsshhh lol

[mikienmb05]

and here it is lil pricey but whatever

https://www.battlescooterstore.com/sess/utn;jsessionid=154bf9b38712ac3/shopdata/?main_url=go.shopscript%3Fa%3D12040018