K&N air filter for a 125cc

DeeDee · Post by **DeeDee** » Thu Oct 23, 2014 3:21 pm

Has anyone got rid of their stock airbox will the attached emission hoses and canisters and replaced it with an aftermarket performance filter? I've searched the forum, and have come up empty handed. Or... has anyone taken the overflow tube off the check valve and simply let it hang down away from the muffler? I had a SYM HD200, and there was a lot of talk on this subject on the SYM forum. Thank you!

jrsjr · Post by **jrsjr** » Thu Oct 23, 2014 9:00 pm

I don't want to discourage innovation, but you should should search this site carefully for threads about modifying the airbox. There are different schools of thought about this. Here's my thing. I have yet to see a dyno printout that definitively shows an improvement.

Years ago I rode my old beemer to a national rally where they had a mobile Kerker dyno. We had just done the dual-plug conversion and the three angle valve job thing so my R100 motor was running its best ever. Anyway, I ran my bike on the dyno and I thought the results were wonderful. The guy who was running the dyno showed me a small but noticeable notch in the HP curve which he offered to cure for the princely sum of nothing. He drilled a little hole just so in the airbox cover and, lo and behold, it got rid of the notch! I couldn't tell the difference just riding around, but that graph made my buddies so jealous that they were lined up for hours with their beemers at the dyno concession.

Seriously, without a dyno, it's extremely difficult to do that kind of tuning. About the best you can do is find somebody who's gotten consistent good results with a particular method and follow their lead. In this case, I'm unconvinced that anybody has a proven method that everybody agrees works. Again, search around this site and see what you turn up and do some innovating.

One last thought - Eric Buell was famous for getting more power out of the Harley Sportster's mill by putting a huge resonating airbox on the intake. Maybe you will be the one to crack the code and figure out how to do the same with the Genuine Buddy. In fact, that would be a great 3D printing project. How insanely cool would it be to have a hotrod Buddy scooter with a giant Buell-inspired 3D-printed custom airbox? Somebody might even be able to make a little money with that product, you never know. On the other hand, after much hard work, it might turn out that the stock airbox is really well designed to start with.

Good Luck!

skipper20 · Post by **skipper20** » Fri Oct 24, 2014 4:54 pm

DeeDee wrote:Has anyone got rid of their stock airbox will the attached emission hoses and canisters and replaced it with an aftermarket performance filter? I've searched the forum, and have come up empty handed. Or... has anyone taken the overflow tube off the check valve and simply let it hang down away from the muffler? I had a SYM HD200, and there was a lot of talk on this subject on the SYM forum. Thank you!

My '09 Blackjack 150 does not have the stock airbox. The PO made a clean removal and installed a K&N air filter. I'm sure the carb was rejetted to compensate for the difference in airflow. Anyway, the bike runs extremely well and easily tops 60 mph.

Bill in Seattle
'09 150 Blackjack
'12 170i Italia
'08 250ie Aprilia Sport City

Gma Dot · Post by **Gma Dot** » Tue Nov 04, 2014 8:30 am

I too am looking to put K & N filter on my new Buddy 125 Riot. I love this little scooter but would like a little more power. And how about a K&N oil filter. I am going with a full synthetic oil. A newly after several years. Want to know all mods I can do myself. Suggestions welcome.

BuddyRaton · Post by **BuddyRaton** » Tue Nov 04, 2014 1:13 pm

I don't think an air box mod is going to do much unless other items are addressed. You can't get more air in if you can't get more air out.

BuddyRaton · Post by **BuddyRaton** » Tue Nov 04, 2014 1:15 pm

Gma Dot wrote: I too am looking to put K & N filter on my new Buddy 125 Riot. I love this little scooter but would like a little more power. And how about a K&N oil filter. I am going with a full synthetic oil. A newly after several years. Want to know all mods I can do myself. Suggestions welcome.

I would suggest breaking it in before going full synthetic or doing any other mods.

Icecreamman · Post by **Icecreamman** » Thu Jul 28, 2016 5:15 am

Lowe's 2 stroke air filter fits right in the hollowed out original.

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wheelbender6 · Post by **wheelbender6** » Thu Jul 28, 2016 3:15 pm

I think the main benefit of a high performance air filter is quicker throttle response, vice power increase.

lovemysan · Post by **lovemysan** » Fri Jul 29, 2016 3:10 pm

On a stock or lightly modded motor I'd keep the airbox. Your bike will make more power with the air everywhere but WOT. A very common mistake when modding scooters is to delete the air box and attach a filter to the carb. A CVK does not perform its best like this, CVKs prefer smoother air and the engine and air box are tuned together. In simple terms: the theory the air box has a specified volumn, the engine draws a column of air moving at speed through the carb into the engine. Once the piston reaches the bottom of its stroke the column of air is forced into the cylinder because of momentum. Its like supercharging to a small degree.

I deleted my air box this spring and picked up 10mph top end. But my bike is far from stock. With the air box delete I drilled the main jet to a 145.

wheelbender6 · Post by **wheelbender6** » Sun Aug 28, 2016 1:49 pm

I took the baffle out of the stock air box on my slightly modded Buddy (jet and exhaust) and lost a lot of torque.
I will be trying to make a replacement baffle with a velocity stack replacing the tube.

Roofaloof · Post by **Roofaloof** » Mon Aug 29, 2016 4:34 am

Has anyone got rid of their stock airbox will the attached emission hoses and canisters and replaced it with an aftermarket performance filter?

Yes, I did this on my '09 Blackjack. I replaced the stock airbox with an intake manifold and foam air filter.

I was able to rejet the carb and get it to run properly after building and installing it.

You can find a brief writeup I did about how to build it here: viewtopic.php?t=25345&highlight=roofaloof

Does it make more power? I think so. As others have said, it's impossible to know without a dyno. However, it runs very well and sounds amazing!

Whether or not it makes more power with a mod like this doesn't matter.

Actual power output is only one part of how fast your scoot feels to you. Is it possible to notice an increase in power of 0.5 hp on a 10hp engine?

After an airbox mod like this, I guarantee your scoot is going to feel a heck of a lot faster. Your stock airbox is designed to make the engine as quiet as possible. Most folks don't want to hear the sounds it makes.

With a custom air intake, you'll get to hear how your engine really sounds. Personally, I love how my scoot sounds with its intake. At part throttle, it's somewhat louder than stock. At full throttle it's genuinely loud.

Riding a scoot that sounds fast will make it feel faster to you. When you twist the throttle, your scoot is going to let you know it's accelerating.

If this is the first mod you've done, it probably won't make any more power. It probably won't make any less either. It's going to sound better (IMO) and would be a great place to start with tuning your scoot.

Modern Buddy

K&N air filter for a 125cc

K&N air filter for a 125cc

Re: K&N air filter for a 125cc

Re: K&N air filter for a 125cc

K&N filter for Buddy 125

Re: K&N filter for Buddy 125