Unofficial Royal Enfield Community Forum
Royal Enfield Motorcycles => Bullet with the UCE engine => Topic started by: Arizoni on November 20, 2013, 10:28:54 pm
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A few days ago I was in the local O'Reilly's Auto Supply store and noticed a air filter that looked almost like the paper filter used on the UCE Royal Enfields.
Rather than having orange rubber ends it had black ones and the paper was white.
A nice screen on the inside and outside connected the ends.
The filter is made to replace filters for KOHLER K181, Tecumseh HH80 & VH100, John Deere AM30800 and Tecumseh 31925, most of them being small single cylinder applications.
They only wanted $7 for it and I figured that was a good price if it worked so I bought it.
After getting home I did some measuring.
The OEM air filter measures 3 inches inside diameter, 4.7 inches outside diameter (the orange rubber ends) and it is 2.90 inches tall.
The outside screen is about 4.62 inches in diameter X 1.7 inches tall giving an open area of about 24.7 square inches of open area.
The newly found filter measures 3 inches inside diameter, 4.4 inches outside diameter (the black rubber ends) and it is 2.4 inches tall.
The outside screen is about 4.3 inches in diameter X 1.7 inches tall giving an open area of about 22.9 square inches of open area. This is about 7.6 percent smaller than the OEM filter.
The shorter length of this filter was too short to work with the bikes stock metal end cover so I bought a roll of .61 inch wide masking tape to work as a spacer. This masking tape has the same 3 inch inside diameter as the new filter and with it stacked on the end of the new filter, the metal cover clamped everything in place.
With the tape and new filter installed I took it for a ride.
In city traffic it seemed to work as well as the OEM filter but when I'm riding around cars I go with the flow so this really didn't test the overall performance.
The next day I rode over to get on a smaller freeway in my area to see how the bike would run at higher speeds.
This freeway is climbing a grade where I get onto it.
It climbs about 250 feet rise in elevation over a distance of 3/4 of a mile. The speed limit is 65 mph.
Accelerating thru the gears with a wide open throttle, the bike was working hard to get up to 60 mph and 70 mph was the maximum I could get to before I turned off on an exit ramp about 3/4 of a mile from where I got on. The overall feel of the bike was it was definitely running out of power.
After this ride I blew the dust out of my old OEM air filter that had over 1000 miles on it and replaced the new filter with it.
Returning to the freeway on ramp I again accelerated at WOT and the bike pulled smoothly to 77 mph and was still accelerating by the time I reached the exit.
The bottom line is if you want to buy this other filter to save a couple of dollars and you ride sedately on city streets it probably will work.
If you ride the freeways at all, the smaller filter will leave you wanting.
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Thanks for the report, Jim. Even way after the 7500mi/12000km service (where the manual tells us to replace the filter), I am using the same (stock) one as it was never that bad. Just gave it a good clean with an air-compressor and put it back. The bike has always ran fine with it. I do have a spare filter lying here (OEM one), so if it needs to be replaced, I have it on hand.
But it is good to know regarding the smaller filter size and how it can affect performance etc. I don't think I will be changing to any aftermarket filter as the engine aspect of my Bullet is stock and will probably remain like it is.
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WIX 42371 and/or Napa 2371 are close to the stock dimensions, pretty cheap, and easy to get most places. Specs OD 4.4", ID 3", HT 3.4".
Oh, and there are two OEM filters. An older one that was a bit wider and shorter, and a newer one that is taller and smaller around. I think the new one is the only one you can get now, but you never know with RE ;)
Scott
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Pretty interesting, how less then 2 sq in. made a 7 mph drop in top end..... Did the screen on the filter seem restrictive ?
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It seems about normal for the smaller filter area being 7.6% less.
If you take 92.4% of your max speed of 77mph, you get 71.148 mph, which is close enough to 70mph to probably be within the margin of error of that speedo.
So, it is a pretty good correlation of reduction of size vs reduction of top speed.
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That settles it! I'm stacking two together tomorrow and I'm going out to break the ton!
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Interesting stuff.... What is the effective filtering area of that K&N replacement filter for example ? .... That you hear conflicting opinions on. Are they the same size ?...... Are they being oiled ?.... not oiled ?.... over oiled ? Is it restricted in the box ?
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MY Orielly Air filter is actually a little larger than the original, & pleated white paper(no metal)& black rubber. Mine works better than stock on my G5, in all circumstances.
I like white pleated paper filters, & have used them for years.
I can't remember the part # of mine, but sounds like yours is to small.
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I bought a K and N for my B5, and on top of being expensive, fit like crap. I don't think performance was enhanced one bit either. I'll buy a stock filter the next time. Now...has anyone managed to find a decent and locally available oil filter?
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I bought a K and N for my B5, and on top of being expensive, fit like crap. I don't think performance was enhanced one bit either. I'll buy a stock filter the next time. Now...has anyone managed to find a decent and locally available oil filter?
Help me understand this: It was the FILter's fault that it "fit like crap"?
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Why do people have this false believe that K&N filters magically give you horsepower? I hear it all the time "K&Ns give you like 10-15 hp". No. No they do NOT give you hp. If you actually read the package it says it "can produce 10-15 PERCENT HP increase over stock". These filters do not increase HP, they increase the efficiency of how the motor operates. The UCE has about 29 block HP, even if the motor was able to actually scavenge a full 10% increase, that's only 2.9 HP increase. If you have a full stock set up, regardless of the vehicle, you're not going to see any gains because your heads and TB are still flowing the same amounts they always have, and that's where the real increases come from.
Scottie
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More like 18 or 19 at the rear wheel..... And even at that. IF , and thats a BIG IF ! Without fuel corrections of course..You could pick up a cheap 10-15 % increase in HP.... You're doin' alright. HP ain't easy to come by on these bikes... I think K & N actually claims UP TO 4 %... I could be wrong on that though.
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Isn't marketing great...Can you imagine the amount of air filters and filter oil they sell over the years...I'm just as guilty as the next guy , with one retrofitted inside the enfield filter box and as part of a stage 1 kit on the yamaha...Both bikes start up great and I think they go faster... ;D
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Don't get me wrong they are good filters and I have used them on several different cars, trucks and bikes I've owned. It made a big difference on my'83 Suzuki.
Scottie
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Okay, a couple of basics.
The filter element should be rated for the same (or greater) flow in cfm as the engine inlet system can pass. This helps prevent a low pressure zone from being created inside the filter element. The engine ingests air by the difference in pressure outside the throttle body(preferably full atmospheric pressure) and the partial vacuum in the cylinder during intake. If the air outside the throttle body is pulled lower than atmospheric pressure by a restrictive element, then that reduces the available outside pressure to feed the engine.
Also, the internal air volume space inside the filter mesh barrier should be as large as is feasible, and should be at the very least the same as the engine displacement. This allows the engine to take a full "gulp" of air without having to pull air thru the filter mesh. It gets almost an unrestricted gulp from this internal volume, and then the internal volume can re-fill with air during the next 3 engine cycles, and be ready for the next intake gulp.
And, the mesh should be fine enough to filter the particles out of the air at the desired filtration spec, and have enough area to ensure the flow rate even after it has gotten a bit dirty.
A suitably sized pleated paper filter element housed in a properly sized air box is probably the best overall solution. This is why we use this formula in the construction of our Ace Air Canister. It's simple, but it follows the proper design criteria. The factory design has some of the right concepts, but it could be improved. I think it has also been established that the small pod filters like K&N have not given good results in this application due to insufficient internal volume.
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Why do people have this false believe that K&N filters magically give you horsepower? I hear it all the time "K&Ns give you like 10-15 hp". No. No they do NOT give you hp. If you actually read the package it says it "can produce 10-15 PERCENT HP increase over stock". These filters do not increase HP, they increase the efficiency of how the motor operates. The UCE has about 29 block HP, even if the motor was able to actually scavenge a full 10% increase, that's only 2.9 HP increase. If you have a full stock set up, regardless of the vehicle, you're not going to see any gains because your heads and TB are still flowing the same amounts they always have, and that's where the real increases come from.
Scottie
I agree but for some vehicles the filter is a larger restriction than their intake components. these days however considering most automotive/motorcycle makers know this fact and that most people clamoring for better fuel efficiency and more power have taken this fact (makers) and used it to optimize their vehicles from the factory. So its almost useless to install a higher flowing air filter in some cases. This is not true for all.
I used to think K&N filters were the best filters a person could get, however after working on a fleet of diesel trucks I have found K&N filters do more harm than good. The main reason this company invested into K&N filters for its fleet is over time it was cheaper than buying paper filters often. What they saved in paper filters they spent on engine repair. One truck that sticks out in my mind ran a K&N from day one, it was cleaned and oiled on its regular interval as recommended by K&N with their cleaning kit. However that didn't stop fine particles making their way into the combustion chamber and scratching the cylinder walls. Though the engine had 200k on the odo it should have had a longer life.
Now keeping that in mind I really doubt any of us will put 200k on our bikes but id love to see it. The point is K&N filters flow better cause their fibers are spread further apart and generally cannot filter as fine of particles as a paper filter. The oil on the filter is supposed to catch the finer particles, which it does but not as good as paper.
As said before a K&N filter does not create power magically, if either the original filter is the larger restriction or you have supporting mods (larger tb,larger valves,bore out intake passages) then you are simply not getting anywhere.
Just my opinion but all your buying is an expensive filter that you now have to clean and oil as well as spend more money on the cleaning kit. To each his/her own, no hate here.
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I had a K&N filter in my RE and it worked quite well. I saw no change in mileage or speed, so the engine operation and power were basically unaffected by the filter. To spend all that time it took to clean it an a rare occasion, saves me the time and gas to have to go down and buy a paper one.
I was happy with it. I have a BMC filter in my Goose, very similar to the K&N, as there is no K&N available for the Goose. If I can't make it past 200K, well, crap! But if it's letting more air in, it should be making a bit more power. The bike runs good, but not having put it on a dyno, I can't really say how much help it's been.
Bare
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I had a K&N filter in my RE and it worked quite well. I saw no change in mileage or speed, so the engine operation and power were basically unaffected by the filter. To spend all that time it took to clean it an a rare occasion, saves me the time and gas to have to go down and buy a paper one.
I was happy with it. I have a BMC filter in my Goose, very similar to the K&N, as there is no K&N available for the Goose. If I can't make it past 200K, well, crap! But if it's letting more air in, it should be making a bit more power. The bike runs good, but not having put it on a dyno, I can't really say how much help it's been.
Bare
Bare
+ 1.... I THINK when people drop in a K&N. They EXPECT to see at least some feeling of better performance.... it's Painted on all them race cars and such !... And they don't. Or even feel that because they don't, it's worse? There is SOOO! much more to it then putting in a different filter ! It's ONE thing, that affects another... which affects another... etc.
Their language.... and language is everything. Especially words like "CAN"..... instead of " WILL"
http://www.knfilters.com/faq.htm#&&/wEXBgUIQVBQX1RZUEUFAnBzBQ5SRUZFUkVOQ0VfTkFNRQUIQVBQX1lFQVIFCUFQUF9NT0RFTAUMU2VsZWN0IE1vZGVsBQhBUFBfTUFLRQULU2VsZWN0IE1ha2UFCkFQUF9FTkdJTkUFDVNlbGVjdCBFbmdpbmUFCEFQUF9ZRUFSBQtTZWxlY3QgWWVhcjzBFG60dZ/dUdYOaw3Yl4yvEJ1/SI9CmSL03LLJZHtN
http://www.knfilters.com/filter_facts.htm#RESULTS
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I had a K&N filter in my RE and it worked quite well. I saw no change in mileage or speed, so the engine operation and power were basically unaffected by the filter. To spend all that time it took to clean it an a rare occasion, saves me the time and gas to have to go down and buy a paper one.
I was happy with it. I have a BMC filter in my Goose, very similar to the K&N, as there is no K&N available for the Goose. If I can't make it past 200K, well, crap! But if it's letting more air in, it should be making a bit more power. The bike runs good, but not having put it on a dyno, I can't really say how much help it's been.
Bare
I don't like cleaning those things after having to do it on a fleet of vehicles :'(...lmao
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+ 1.... I THINK when people drop in a K&N. They EXPECT to see at least some feeling of better performance.
And that's what people usually get, a feeling of more performance.
"Dude, can you feel how it accelerates better?"
"Um, yeah, uh, I guess so."
Never hurts that you can often hear more of the intake howl.
Scott
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Eggs- actly......
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When I had my '83 Suzuki 550, it had come from Washington State and was never jetted and tuned for the mile high altitude so it was always running rich. When I installed the K&N filter it allowed enough extra air to enter the combustion chamber to help balance out the rich A/F ratio and stopped puffing black smoke out of the back.
Scottie
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"Dude, can you feel how it accelerates better?"
"Um, yeah, uh, I guess so."
Haaaaaaaaaaaaaaaaaaa exactly..Another satisfied customer...
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When I had my '83 Suzuki 550, it had come from Washington State and was never jetted and tuned for the mile high altitude so it was always running rich. When I installed the K&N filter it allowed enough extra air to enter the combustion chamber to help balance out the rich A/F ratio and stopped puffing black smoke out of the back.
Scottie
Pretty good example Scottie of what it "CAN" do.
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Pretty good example Scottie of what it "CAN" do.
Exactamundo! What CAN happen when all other factors line up correctly in the order they need to be. LOL
Scottie
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I think anytime someone sells an aftermarket anything, they insinuate better performance. I got sucked into the whole K and N filter thing by NOT doing research. Live and learn. Yeah...maybe on a carb job it MIGHT squeak out some extra power with some other tuning and tweaks, but in an EFI (as my bike racing dealer pointed out) you've pretty much have it all without tearing the whole thing apart and polishing this and modifying that. In any case, I'm not here to bitch, just report MY observation. A 500cc bike like my '09 G5 military has it's limitations, one being one cylinder...either live with it or graduate up..
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Wrap a piece of gauze around a piece of window screen and stick it in. It's cheaper and filters better than K&N.
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I don't own a C5 or B5 so I can only say what I found on my G5 when I put the K&N filter on it.
Aside from the overoiling issue, when I finally got it cleaned up and oiled very lightly my home made flow test device did say it flowed a little more air than the stock paper filter.
The only thing I have to test power is my butt on the seat of the bike. That said, my butt said the acceleration with the K&N installed was slower. The fuel economy also went down while the K&N was installed.
The stock air filter is 4 3/4 inches in diameter. The conical outside of the K&N is 4 3/4 inches in diameter at the small end and 5 5/16 inches in diameter at the large end.
With the K&N flowing slightly better I can only conclude that its larger diameter is blocking off the air flow out of the filter plenum into the air duct that leads to the throttle body.
Whatever it is, I've got a $55+ filter that lives on the shelf in my storage room. :(
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So have we come full circle to state that unless you modify your Enfield with some kind of added performance , it's basically a waste of money to just plug in a k/n air filter..
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So have we come full circle to state that unless you modify your Enfield with some kind of added performance , it's basically a waste of money to just plug in a k/n air filter..
Not exactly. The K&N is great for carburated bikes, but it does cause issues with the UCE fuel injection.
Scottie
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More on the adventure of the air filter:
As I was looking at the inside of my plastic air filter plenum I noticed the hole thru the back wall where the air comes into the inside of the filter seemed rather small for a filter with a 3 inch inside diameter.
It turns out that the hole is only 2 1/2 inches in diameter and the metal piece that runs down the center is almost 5/8 inches wide. That leaves an open area of about 3.4 square inches, the equivalent of a thru hole that is 2.08 inches in diameter.
I realize the paper filter material is a substantial blockage but the area of the inside of the paper filter is at least 16 square inches in area.
With this in mind I set to work with my Dremel tool to see if I could enlarge the inlet hole, at least to about a 1 1/2 inch radius.
Because of the metal strap down the center of the hole and the two wiring harnesses that are immediately behind it I had to leave the central area alone but I did manage to enlarge much of the hole towards the front and rear of the motorcycle.
On today's ride up the local freeway I was quite amazed.
The bike accelerated effortlessly to over 80 mph and was still accelerating when I had to back off for the slower car ahead of me. Remember, this is climbing a moderate grade.
I also noticed that from a stop light, the engine seemed to rev up much faster and it didn't seem to be losing power at the higher revs.
My buttometer and earometer seemed to think the bike was accelerating faster at WOT in all gears.
Maybe it was due to the cool air temperature (56 degrees F)? Maybe it was due to the humid air (60 percent)? Maybe it was due to the enlarged air inlet?
Below is a drawing that shows the added inlet areas. You may not be able to enlarge your inlet as much as the drawing shows. I know because of the wiring behind the plenum and some frame tubes I couldn't. I also "hit metal" when I was removing the plastic the inlet is made from so I stopped when that happened.
If you try this on your bike, be sure to get all of the filings/grindings out of the inlet plenum before buttoning it back up. It's a direct path into the engine for anything that is left behind.
I am hoping that someone on the forum will try this on their RE's inlet and let us know if it makes a difference. It may have been a fluke but if it's not, it might be the best thing since sliced bread.
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I'll check my C5 when I get home. I think in addition to the small opening, on the C5 there is a shroud to prevent any water/crud getting in since the opening faces the center of the bike near the fender. I think that opening may be even smaller.
When I had the pod filter mounted right on the throttle body, there was certainly a bit more power everywhere and a beautiful intake howl. But the drop in MPG indicated it was a less than perfect solution. That said, I think you may be on to something, spotting the inlet as a restriction.
Scott
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As you may know, my bike is a G5 and I have no idea what the C or B bikes plenum looks like.
There did seem to be some baffling behind my air box to keep out water but I didn't fool with it.
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Prof Stack tested his C5 on a dyno and noted that just opening the airbox (with a KnN) resulted in a 5% HP gain at the rear wheel when compared to closed airbox (With a KnN).
http://www.enfieldmotorcycles.com/forum/index.php/topic,10706.msg125425.html#msg125425
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Arizoni:
That sounds a good idea to open up the hole a bit. On my G5 also the electric wires run right behind the air hole across the middle, so widening the hole has to be done very cautiously.
Ducati:
How does your C5 look compared to G5 whose pictures I have attached below ?
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i did increase the inlet hole to dia.80mm(3.15") just as arizona did. Yes the bike feels smoother at all rpm's. It does easily accelerate to 110+ Kmph (70mph). An exercise worth doing on the C5.