4 stroke aftermarket airfilter

Gammaray · Apr 4, 2014

Greetings to you all, thanks for having me here apart of this awesome and extensive site.

I have been interested in buying an air filter for my 49cc Hua Sheng engine. And I came across this filter which I probably will buy in the end.
http://www.sickbikeparts.com/catalog/product_info.php?cPath=25&products_id=134

But I have noticed a potential alternative; such as this velocity stack and filter which is my second option:
http://www.affordablegokarts.com/mm...ode=A&Product_Code=1504&Category_Code=MTRBK49

And my cheapest option is:
http://www.adaracing.com/pocket-bike/air-filter-kit-49cc-midbike-pocket-bike/pbafk-49

Although I have no idea if the last one will fit. Is there a danger that it wont? Im leaning toward the last one because its free shipping and only 15$. what a deal!

I do understand there is a breather filter required as well, but that's not a concern for me because i can make my own :-||

.

Thanks in advance.

Lastly here is my engine and carb respectively that im dealing with...
http://www.gasbike.net/HuaSheng-49cc-Engine-Only.html
http://www.gasbike.net/bike-motor-engine-4-stroke-carb.htm

The_Aleman · Apr 4, 2014

I've had the SBP air filter on my Huasheng for a couple years. It works well and looks a lot better than the stock box. It's kind of like a K&N.
No breather filter required with this one, as it has a PCV-style feedback.

The AGK filter supposedly works very well, but many members are having trouble getting ahold of them for any orders right now. Proceed with caution.

The pocketbike version would likely need an adapter that fits your carb. The bolt spacing is critical.
It would likely also require special bolts that can accommodate the way a Huasheng carb mounts.

The route of least hassle will be with the SBP.

Also, be very careful installing. There are 3 gaskets on a Huasheng intake assembly. Keep an eye on what's what.

scotto- · Apr 4, 2014

The first good breathing air cleaner I put on my 49cc Huasheng was infact a K&N conical filter with an ADA velocity stack that I did have to adapt. It worked great and was pretty easy to do.

I've used the AGK adapter since then and they are a piece of cake to install.

dnut

SlickChik · Feb 5, 2016

I just installed the uni filter and adapter from agk and I don't know what to do with the pcv-style feedback... sandwich it between the two layers of foam in the air filter?

culvercityclassic · Feb 5, 2016

SlickChik said:
I just installed the uni filter and adapter from agk and I don't know what to do with the pcv-style feedback... sandwich it between the two layers of foam in the air filter?

I have done that in the past, it works.

MotoMagz · Feb 5, 2016

I brought one years ago and drilled a hole in the side of adapter

SlickChik · Feb 5, 2016

Smart idea.

KCvale · Feb 8, 2016

Velocity stack for a little 4 stroke engine..
Pfftt, I rank that right down there with a boost bottle for a 2-stoke engine as useless.

First any kind of air clearer kills any effect it might of had which is nothing, they are meant for supercharged engines to let all the extra air in on Dragsters with no regard for filtering.

I use the SBP air cleaner with an input for the crankcase vent because they look cool.

For performance and overall best engine operation is just put that vent hose to a catch can so the engine doesn't have to try burn its waste in the input mix.

SlickChik · Feb 8, 2016

Your filter does look cool...

I didn't realize I was buying a velocity stack... I thought it was just an adapter so I could use a uni air filter. Live and learn

Now I think I need to jet the carburetor because now I need to keep the choke on halfway to get the bike to run well. I believe keeping the choke halfway open is allowing more fuel in the carb (due to less air) ? Any ideas where I can just buy a couple different sized jets instead of drilling mine out? Is the current stock jet in the Huasheng two sizes about the GX50 which I think is a 55?

KCvale · Feb 8, 2016

SlickChik said:
believe keeping the choke halfway open is allowing more fuel in the carb (due to less air) ?

Only the air passing over the carbjet collects and mixes fuel properly as it goes.
If you have to use choke to cut out air flow it is because you have an air leak past the jet in the crab and that collects but not mix right will all the extra raw fuel.

http://motorbicycling.com//www.pinterest.com/pin/create/extension/

MotoMagz · Feb 8, 2016

SlickChik said:
Your filter does look cool...

I didn't realize I was buying a velocity stack... I thought it was just an adapter so I could use a uni air filter. Live and learn

Exactly I to bought a adapter to put a cool air filter on my bike..nothing to do with a velocity stack.This was way before SBP offered a 4 stroke air cleaner. That shift kit was the Beta tester kit for the shift kit Psssft!

SlickChik · Feb 8, 2016

Maybe the air leak is between the carb and the engine. I was going to get some gasket sealant to put on those gaskets

sbest · Feb 8, 2016

I have used K&N filters for years in cars and truck.
They do flow more but do let dust and grit by.

If you are into serious dust, UNI can keep it out of the engine.
I use them on my KTM and Husaberg motorcycles.

Steve

KCvale · Feb 9, 2016

MotoMagz said:
SlickChik said:

Your filter does look cool...

Click to expand...

Ya, I like it and there is room in the frame for it.

This was way before SBP offered a 4 stroke air cleaner.
That shift kit was the Beta tester kit for the shift kit Psssft!

Click to expand...

What shift kit?
I remember SBP's 1st 2-stroke shift kit, man was that was hard to install.
I don't remember a different 4-stroke shift kit.
My 4-stroke shifter builds use my 10G KCK Long Shaft, The output shaft is on the right above the pedal sprockets ;-}

http://motorbicycling.com//www.pinterest.com/pin/create/extension/

Kustomized Hypnosis · May 8, 2016

I use the SBP air cleaner with an input for the crankcase vent because they look cool.

For performance and overall best engine operation is just put that vent hose to a catch can so the engine doesn't have to try burn its waste in the input mix.[/QUOTE]

Are you saying the crankcase vent hose pictured here going back into the filter can be left hanging? Or does it need to be routed into something to catch spent air/fuel? And then plug the hole in the filter?

KCvale · May 9, 2016

Kustomized Hypnosis said:
Are you saying the crankcase vent hose pictured here going back into the filter can be left hanging? Or does it need to be routed into something to catch spent air/fuel? And then plug the hole in the filter?

The vent hole lets hot gasses escape, oil residue comes with it.
Never plug this, the crankcase needs to vent.
Cars do this with a PCV valve.

Yes you can just dump it into a 'catch can', It's not as 'green' that way.

But does it help performance?
Yes it should, if you do it right.
I have no example, I try to stay as green as I can.

http://motorbicycling.com//www.pinterest.com/pin/create/extension/

sbest · May 9, 2016

PCV stands for Positive Crankcase Ventilation and it is a way to make power.
Blowby and the piston's downward movement build pressure in the crankcase, impeding the piston's downward movement.
By putting vacuum on the bottom of the piston you increase the effective force on the crank.

The basic theoretical horsepower formula is PLAN/33000 ignoring friction losses.

Where:
P=Mean Effective Pressure in Cylinder (MEP)
L=Length of Stroke in FEET (times 2 for Double acting engine)
A=Area of Piston in Inches
N=Revolutions per minute

Since 1 HP = 33,000 ft-lbf/min

MEP = mean effective pressure, the average pressure over the length of the stroke.

The MEP on these engines is typically 50-100psi depending on tune.
Friction losses are typically 10-25% depending on a lot of things.

Putting vacuum on the bottom of the piston has the potential add about 3/4hp if you do the math.
On a V8 car racing engine the potential is about 50hp. These potential values are rarely realized.

Steve

KCvale · May 10, 2016

sbest said:
PCV stands for Positive Crankcase Ventilation and it is a way to make power.
Blowby and the piston's downward movement build pressure in the crankcase, impeding the piston's downward movement.
By putting vacuum on the bottom of the piston you increase the effective force on the crank.

Damn I love smart people!
I hadn't even thought of that.
Too many years dicking with 2-stroke engines I guess hehehe.
It sure makes sense though.

Great info. Good job Steve ;-}

http://motorbicycling.com//www.pinterest.com/pin/create/extension/

Kustomized Hypnosis · May 10, 2016

I'm still gathering parts (will post pics of build soon), I have a SBP air filter going on a Huasheng 142F, and I found this catch can :http://www.amazon.com/gp/aw/d/B019OKU1QO/ref=cm_cr_arp_mb_bdcrb_top?ie=UTF8&th=1&psc=1

It looks like it will work with a few slight mods. Mounting might be simple with muffler clamps mounted to the seat tube if there's room and it's the right size, I'll have to see how it fits best when I have all the parts.

Thanks for all the great info in this thread!

DirtyBomb · Apr 24, 2019

KCvale said:
Damn I love smart people!
I hadn't even thought of that.
Too many years dicking with 2-stroke engines I guess hehehe.
It sure makes sense though.

Great info. Good job Steve ;-}

So when your using a catch can to collect the oil and gas coming out of the crankcase breather, does it have to be an airtight and specialized catch can like an automotive one or can you just run the hose off the crankcase into just any old can basically? I just got into motorized bikes and just switched my stock 4 stroke carb to an NT carb, and had been running it with the hose just hanging to the side with no can or anything

4 stroke aftermarket airfilter

New Member

Active Member

Custom 4-Stroke Bike Builder

New Member

Well-Known Member

Well-Known Member

Attachments

New Member

Well-Known Member

New Member

Well-Known Member

Well-Known Member

New Member

Member

Well-Known Member

New Member

Well-Known Member

Member

Well-Known Member

New Member

New Member