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Post by honda4life on Sept 19, 2017 17:41:28 GMT -5
I've heard a lot of suggestions to not use an open element Uni filter...
What about the filter in the airbox?
Thoughts on this?
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Post by gsx600racer on Sept 19, 2017 18:22:11 GMT -5
If its stock, I would keep the air box. If you decide to go with the uni filter you will need to rejet the carb.
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Post by honda4life on Sept 19, 2017 19:10:33 GMT -5
I mean keep the airbox but by a Uni filter to replace the stock filter ...
I'm going to be rejetting When I get it anyway.
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Post by ryan_ott on Sept 19, 2017 19:56:20 GMT -5
The uni OEM replacement is fine to use if oiled. They do flow a little better then the original. It's the pod type filters that require much larger jetting to get in tune.
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Post by ThaiGyro on Sept 19, 2017 21:53:02 GMT -5
The uni OEM replacement is fine to use if oiled. They do flow a little better then the original. It's the pod type filters that require much larger jetting to get in tune. In other threads there were similar discussions. My offering is that if you looking for the best air you can possibly get, then K&N type perform better than foam type and foam is better than OEM...both in filtering and airflow. Have seen dyno results on many high performance engines, for cars and big bikes. That said, the differences in a 49cc or 70cc are more subtle compared to 1 liter, 14K rpm four strokes. Go with what fits your budget and performance goals. |
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Post by honda4life on Sept 19, 2017 22:34:49 GMT -5
In my experience the open type filters such as K&N and UNI are difficult as hell to jet because of the airflow characteristics....
The longer, undisturbed path of air going into the carb the better imo.
I've never had much luck with open designs other than gas mileage dropping quite a bit.
I've decided to retain the stock air box, use the uni drop in filter, remove the "snorkel", smooth out the jagged edges where the snorkel was glued to the air box, and finally I added a rubber "Venturi" I cut from my old stock Ruckus air box.
I think I'll be ok but I'll see once I get it dialed in...
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Post by benji on Sept 20, 2017 9:43:57 GMT -5
The uni OEM replacement is fine to use if oiled. They do flow a little better then the original. It's the pod type filters that require much larger jetting to get in tune. In other threads there were similar discussions. My offering is that if you looking for the best air you can possibly get, then K&N type perform better than foam type and foam is better than OEM...both in filtering and airflow. Have seen dyno results on many high performance engines, for cars and big bikes. That said, the differences in a 49cc or 70cc are more subtle compared to 1 liter, 14K rpm four strokes. Go with what fits your budget and performance goals. I use to have a 78 kawi kz750sr with k&n pod filters. Ran like crap until I went back to stock. Same thing with any intake I've ever had for a car- oem design works best. Maximum airflow is only necessary at extremely high rpm on big motors that don't have a problem supplying vacuum. I knew a guy who built his own 9-second '37 chevy. He used to ride Harleys in the '70s and '80s. He swore up and down that the "new" (at the time) k&n filters and all other 'high flow' filters were junk and didn't do anything but cause the motor to drink more fuel. He had this awesome airbox he built around his air filter carb so he could still use a high flow filter but have more reliable airflow to the carb. He ran that motor for like 2 decades. He pulled it from his old vette he use to pick up chick's with during the Nixon years. |
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Post by ThaiGyro on Sept 20, 2017 10:52:13 GMT -5
Haha...I can see that benji. I always use and air-box. I have played with filters inside and outside. Inside is convenient, outside seems to work for me better here on the small displacement engines. I have never had success with a K&N or UNI filter in open air. I can make them run well, but always at a loss of horsepower compared to an air box/filter.
My stock Gyro has a K&N style filter mounted through the frame, with a short, curved intake runner into a two stage air-box that traps air into a short velocity stack/bell mouth, that is also directly mounted to the PBHG or Tillotson. It runs very well, with premix at 40:1. No filter inside to screw with air flow. Seems a minor difference, but I have found inlet filtering to have much more consistent air volumes, thus, easier to tune.
Here in Thailand, we have temperatures ranging from 82 to 100... most often 95 to 98, but with high humidity. Range in our area is 68% to 90%, but the average is near 82%. Rain and heat and rain and heat. It is that reason that we are beginning to use diaphragm carbs. Tuning is easy and quick, and needed constantly. Idling can be crap, but who cares out in the country? I do go through starter solenoids quicker than the US. (Hehe, about $3.50 here)
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Post by honda4life on Sept 20, 2017 12:01:26 GMT -5
I used to think a pod was better but I've come to realize a longer runner for better atomization, smaller plenum (to speed up the air), is better on most scoots.
I did put a small Venturi on the end of the tube I have running to the stock carb and ground down the stock carbs inlet to keep the airflow smooth coming into the carb.
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Post by ThaiGyro on Sept 21, 2017 2:22:04 GMT -5
There are so many views...and all are dependent on what you are trying to achieve. No true right or wrong answers, only good or bad for your needs.
There is a bunch of math involved, but I try to always simplify that. Bottom line for me is that I like good mid-range power, to go along with whatever your pipe will allow on top. A resonant air box does just that, as it has that resonant balance somewhere in the torque band, as designed by the engineers. It also provides a more stable environment for the air to live with less dirt and water...except atmospheric humidity.
A pod setup can and will achieve and equal performing top end, but at a sacrifice in the mid-range. The bottom end...off the line performance has many factors that make it strong or weaken it. Throttle response from carb & ignition and plug condition, variator tuning, including clutch, bell and belt...
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Post by AtariGuy on Oct 4, 2017 18:59:37 GMT -5
A little late to the party, but i've grown up in the country around the redneck jacked up trucks on 35's. Lots of my buddies go swampin the mudbogs and really tearin s...tuff up. Anywho, their pavement princess trucks would always be set up with cold air intakes - k&n pods inside a resonant box and an oversized snorkel out front sucking up backroad bugs. Seems to me that this idea of having a k&n/uni inside the stock airbox would be a great idea, still offer the resonant box but still get the big air flow a k&n would allow. Would a larger front snorkel help maintain the resonance without inhibiting the top end flow?
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Post by eclark5483 on Oct 4, 2017 19:41:54 GMT -5
I'd just as soon port an intake then modify a simple filter system. Once air hits the carb venturi, the dynamics all change anyway. Better to control at the venturi and after it. Free air filters just change your lean/rich condition for the most part, and you sacrifice vacuum for more air. Get that dialed in, THEN mess with the airbox ever so slightly.
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Post by honda4life on Oct 9, 2017 13:03:17 GMT -5
I have a small "intake" tube that's about 6" long that has a Venturi at the end that I attached to the stock airbox...('09 Zuma) and I took it off and I swear I lost like 2-3mph.  |
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Post by lostforawhile on Oct 9, 2017 19:44:19 GMT -5
In my experience the open type filters such as K&N and UNI are difficult as hell to jet because of the airflow characteristics.... The longer, undisturbed path of air going into the carb the better imo. I've never had much luck with open designs other than gas mileage dropping quite a bit. I've decided to retain the stock air box, use the uni drop in filter, remove the "snorkel", smooth out the jagged edges where the snorkel was glued to the air box, and finally I added a rubber "Venturi" I cut from my old stock Ruckus air box. I think I'll be ok but I'll see once I get it dialed in... if you are using more gas, it means more air is flowing, unless you are running super rich, that means that extra fuel is making power. the extra air is pulling more fuel through the jets, because you are getting more mixture into the cylinder, which is the point. the extra fuel isn't just vanishing. if your plug look good, and you don't show any other signs of running rich. congratulations, your pod filter is making you more power |
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