High performance air filter kits for 4 stroke?

[KeepOnKeepnOn]

Motomagz, tell me what a 7/8 stack is and tell me more about the simple mods. It looks like you made an adapter to use the typical high performance air filters. Thanks for taking the time to post the pic, a pic of the adapter with out the filter on it would really help.

Hough, I was thinking about screwing a hose barb into my gear box where the vent is, then directing a hose onto my chain. That way all that leaking gear oil would serve a purpose.

 

[MotoMagz]

Air filter and velocity stake

Keepon, it is a 7/8 velocity stake(ebay).The 7/8 opening is the same as the carb.The air filter(ebay) is mounted to the velocity stake.You will need to make a adaptor for the velocity stake out of a large washer to mount it to the carb.I will put some detailed pictures up tonight.thanx MotoMagz

 

[HoughMade]

Hough, I was thinking about screwing a hose barb into my gear box where the vent is, then directing a hose onto my chain. That way all that leaking gear oil would serve a purpose.

That's funny- but mine didn't even leak oil when I had the hose completely open.

 

[KeepOnKeepnOn]

Thanks Moto, I get the idea on your adapter now. Did you epoxy the velocity stack to the washer? Then some formagasket to seal the washer to the carb. Good idea using the velocity stack as a mount.

Hough, I put the recommended quantity of gear oil in the gear box and it has never stopped spewing out, I can't believe it hasn't gone dry yet.

 

[HoughMade]

if you want to try gear oil, no more than 3 ounces, but what bicycles-engines recommends did not work for me. I now use a lot of grease. There are some posts about my gearbox lube search here somewhere.

 

[MotoMagz]

Keepon,I used two 1"aluminum threaded posts w/screws.You can find them at Lowes for a buck each.They have a flat bottom so they won't pull through the holes you will need to drill in the washer. So the washer gets 2 holes to mount stack & 2 holes to mount to carb. Let me know if you need more pictures,thanx MotoMagz

 

[KeepOnKeepnOn]

When you say 1" threaded post you must be talking length not diameter. Steel rod seems like the stronger, easier to find, cheaper way, rather than aluminum rod.
So... no expoxy, countersunk screws holding the stack to the washer (first pair of holes). Nuts on threaded rod, holding the washer to the carb (second pair of holes).
Regardless, I have some workable ideas for attaching a nice air cleaner. Thanks, MotoredBikes kicks arse for ideas to solve problems and inspiration.

 

[MotoMagz]

Yes length and it is a hollow post with threads in the inside so you can secure it with the screw{that comes w/the rod).Welding threaded pipe to the washer and grind it flush was my first thought put got no welder!! MotoMagz

 

[KeepOnKeepnOn]

Here is my solution, which turned out to be a major pain in the rear. It looks great though. No noticeable change in performance.
As Moto suggested I used a large washer with the velocity stack mounted to it and the air filter then mounts to the velocity stack. The opening for my carb was actually 3/4" not 7/8". The distance between the bolts which hold on the carb and original air filter is perfectly wrong, its too close together to sit outside the Vstack and too wide apart to drill right through the Vstack and bolt through it. Instead I had to file away big notches in the base of the Vstack so that the heads of the bolts going through the washer would clear and be useable. The Vstack is epoxied to the washer which locks the bolts in between them, although they turn freely they can't be removed. Also the carb has some openings on the face and the original airfilter clearly had notches to allow air flow past them, so I had to drill and notch for this in the Vstack/washer. Also, the Vstack had mounting holes drilled in it for its original application (goped or mini bike) which I filled with epoxy putty to smooth out air flow as much as possible. The pictures do a better job of explaining than my writing.

Edit: I didn't even look at the pictures until I posted them. They are all blurry but you should get the idea.
I got the air filter on Ebay.

 

[MotoMagz]

It Does look good.I also had to grind out the area for the bolt heads.The only thing I did different was to use the two holes in the stake to mount it to the washer.That way it could all be tightened down.