Air filter upgrade question

[cgward]

I have a 2019 Yongfu Roadmaster yn50qt-29. I'm removing the stock air box doing the K&n replace. What I don't know is how or what to do with the vacuum lines after. Especially the line coming from the drive case. Any guidance would be greatly appreciated.

[donaldsonta]

Some people make catch cans, honestly I've always just had mine drain to the ground. I know it's not the right thing to do, but I did it when I was just getting started modding and didn't know about any resources online. Here's a link to the forum creator doing it right.



49ccscoot.proboards.com/post/229916

[cgward]

Dec 12, 2019 7:43:12 GMT -5 donaldsonta said:

Some people make catch cans, honestly I've always just had mine drain to the ground. I know it's not the right thing to do, but I did it when I was just getting started modding and didn't know about any resources online. Here's a link to the forum creator doing it right.



49ccscoot.proboards.com/post/229916

Thanks for the replay and the great info. I noticed that once I changed to the K&n style filter and took a block ride, the scooter lost a lot of power with some sputtering. The vacume leak was very noticeable. The other issue is the loss of gear oil from the vacume line on the clutch case. I don't mind motifying the stock air box to make way for the filter if there is no other way to stop the loss of gear oil.

[dexameth]

First off

The only vacuum line on your scoot comes from the intake manifold and operates the fuel valve. You may have an emissions system with a sort of pump that is vacuum operated as well. Find the line that comes from the intake and follow it back.

On the very front side of your engine is the PCV (positive crankcase ventilation). That line normally went to the stock airbox to "recycle" the vapors. As the oil in your crankcase heats up, as well as the piston going back and forth, the pressure needs to go somewhere and it leaves thru that port on the front of the engine.

The gearbox, all the way in the back behind the clutch, also has a breather. That breather does the same thing, allows the expanding oil vapors to come out... if oil is coming out there is a good chance it is over flowed. My personal scooter with the same engine doesn't even have a hose connected to the spigot and it's fine, does not leak.

When you switched to the pod style filter, you need somewhere to put the PCV line now. I purchase a 5 foot section of hose from a local auto parts store and zip tied it along my frame all the way to the back by the fuel tank. After a few weeks of riding there is a film of oil, but it's easily cleanable. You can also run that same line right to your carb and zip tie it in place so that the end of the line is right at the air filter - will act like the stock setup at that point. Most people I know run a UNI style, dual stage, filter and put the PCV line in between the two filter elements.

Hope this helps!

[cgward]

Thanks Dex, yes that info is very helpful. Think I got this now. You guys are great and I really appreciate all the feedback. Now I just have to reject the carb and I'll be set till the exhaust and big bore get here. Happy scootin and I'll see yaw in the near future.