Monday, August 12, 2013

Keeway TX200G Air Filter Modification

12.7Hp stock on this machine was sufficient for me. With good torque of 13.5Nm, this bike (ownership 3months) served me really well for daily commuting and the occasional countryside riding. However, the maximum power and torque comes in at very high RPM that is typical of any motorbike. I hardly twist the throttle fully open, let alone for it to touch 6500rpm (for max torque) or 7500rpm (for max power). So what do one do? 
A typical hot blooded male with some knowledge with engine and working of a 4-stroke combustion engine (and years of modifying a family car to squeeze blood out of stone, so they say) will tell you this - Let the engine BREATHE. 
Open Pod
Going open-pod or those cone filter is actually the most logical way to go. But with my stock carb at 27mm, finding the replacement part is tough. The Keeway TX200G came with a huge air-box for the motorbike which actually takes up almost the whole space below the seat.
The two holes are the air intake holes, It is part of the triangular looking box below
While aftermarket open pod filter (legit performance parts) cost anything between RM60 to RM300, I ended up with a RM4 solution. Aquarium filter.
Yes, you read me right.

Original filter on left and Aquarium filter, right.
My whole reasoning for this is to actually free up some low end power. Restrictive intake hasten the pick-up of an otherwise spirited bike. A check on the local TX200G bike group has returned mixed review - as most of them that has modified their bikes removed the filter altogether and run them filter-less. 
This filter-lemma came about after I've learnt to tune the carburetor from a fellow rider - making the mixture a bit richer that stoic condition which has lend more power to the bike at low end. Essential for city riding as you want to get in and get out as fast as you can (away from distracted drivers). So, with the carb tuned, the air-filter needed to be sorted out to allow for more ready air flow at high RPM. Filter less, as they said (and experienced), was the way to go.
While I must admit I am tempted to do that, but I am conservative (slightly) with this approach as to prevent things like leaves or gravel from entering the carburetor and destroying whatever that works.
I know, there is NO way gravel or leaves could go into those puny holes. Lets see them again.
Leaves goes in under the seat? really? Stones??? Come on, you got to be joking me!
But I still take the more conservative approach. It has to have a filter - and it gives me excuse to modify something.

Disclaimer - I will not be responsible for any damages caused with this modification undertaken by yourself and this modification was done solely as an experimental purpose only. Please be reminded that if you constantly ride in highly dusty condition or take your motorbike into the desert, this modification is highly not recommended. Sand particles against internal moving parts spell disaster with capital F.

What You Need
1. The aquarium filter mesh obviously
2. Screw driver to fit your bike
3. Scissor to cut the filter
4. Some imagination (and ability to cut straight)
The dense filter sponge on right and the looser filter mesh on left. Shown original size.
The best way to do this is to cut the replacement filter using the original as the template. It is as simple as holding it firmly against each other and cutting it to size. 
No brainer which to use, really.
Once cut to size, place the mesh filter onto the filter holder. Note that the original filter has two holes. Those are there to hold (or sort of) the filter against the filter holder. As the original filter box is large, this setup was done to allow a stiffer "bracket" to hold the softer sponge. All you need to do is to press the mesh filter against the  holder and the protrusion on the filter holder will penetrates through. Easy.
Press it down. Done.
 Here is the completed filter in the filter bracket.
 And here is the original filter in it's bracket.
Awesome too (in super dusty condition)
And once you are happy with how the filter holds up in the bracket (that including trimming off loose edges) you simply slide it back into the filter box. Screw back the filter cover, put back the fairing/bodykit. You are done. 
Yeah baby!

  • I started the motorbike and twisted the throttle. I immediately felt the lighter and less restrictive movement of the throttle, sign that the carburetor is working less hard to draw in the air. 
  • The induction sound was louder as the original filter also serves to cut off the induction sound offering a slightly quieter ride. No issue here as it now sound "sportier"
  • I took the bike out for a spin around the neighbourhood and OH BOY, the low-end torque and power were there. It is like less effort to move from 0km/h to 40km/h.
  • I rode to work as it was school holiday (no driver duty) and on the clear road (limit 60km/h and 80km/h) the bike's pick up behaviour changed. At lower RPM the power could be felt and at Gear 5, I could still overtake cars moving at 70km/h. There is no need to downshift to 4th like I usually do.
Cost of modification - RM4 for filter (it comes in two sets of coarse and fine filter, I used only half of the coarse filter). 30minutes. Satisfaction overload.


  1. Hello there,

    Do you know any available or suitable aftermarket air filter for this model?

    Like you I also think this bike quite struggle with its' low end power.


    1. Ahmad Shah - unfortunately the only other way is to use an open pod (28mm diameter to fit the carb?)

      Actually for me it is more of the lag than sluggish low end. Not helping the big airbox where the engine needs to "pull" harder to get the air in.

  2. Can you give us readers a lesson on how to tune the carburetor? Does tuning it affects the idling? Thanks,

    1. Andy - there are only two screws that can be adjusted on the TX. first is the idling which is on the right hand side (screw with spring), turn it counterclockwise to bring the idling down a little. what you can do is idle it in the middle point between the high-revving sound and low-revving sound.

      Second screw is at the front of the carb, underside, closest to engine. that is the Air-Fuel screw. this one a bit tricky to adjust as you will need a paperclip to turn as the spacing is tight. turn it to the left (counterclockwise if you look from the bottom-up) to get richer mixture.

      If you are the same Andy in the FB TX group, i believe you changed your exhaust and thus, requiring a richer mixture. Suggest that you turn the AF screw 1/4 a turn at a time. Run the bike a few K, let the engine cool and take the spark plug out to see the burning condition. If the tip is wet, you are running it too rich. Aim for complete burning without any flashover.

      If the above is too much work, I suggest you just turn it 1/4 turn at a time and ride it until you are happy with how the bike is responding. :) Good luck!

  3. how to open the seat?

    1. Hi! You first need to remove the fairing on both left and right (3 screws each side) and it will expose the two nuts holding the seat.

      remove these two nuts and push the seat to the front a little and you will free up the seat.

      To remove the air filter element, you ONLY NEED TO REMOVE THE RIGHT SIDE. no need to remove seat.

  4. can i remove the air filter box and use racing air filter

    1. Of course you can. It is your bike. :) But any modification voids warranty. Proceed with caution.

  5. the air filter box is heavy or not .btw thank for the replay

  6. as salam bro, saya baru gune motor ni seminggu lebih...n ni motor first yg gune clutch....saya ada prob biler nk start jln la...biler masuk gear satu, die punyer clutch tu, org kater mcm mana...pendek sgt??pjg sgt??...mcm mana nk counter prob mcm ni ekk??

    1. First time bawak kena perlahan dan sesuaikan diri untuk membawa motor clutch. pulas minyak sikit semasa lepas clutch, gerenti lancar.

  7. Salam bro..I'm just bought the TX last month and eager to have some whatnot modification...but I'm just wondering whether the modification on the air filter would affect on the fuel consumption?? if there was, can you explain a little bit on the detail?.. Maybe i need some of your advice before done that..thanks bro

    1. Salam tuan. The FC doesn't change much and if any, it actually improves on my side. It is as simple as either you remove the filter (filterless, but run it with caution esp in dusty/sandy are) or with a modified squarium filter like I did. No issues so far.

  8. Fantastic write up. Keep it going bro

  9. Thanks for all the information man! I just bought the TX200 and what value for money. I changed the carburator yesterday and OMG what a difference in the power. Much better pick up from 1st-4th gear and on the 5th gear, before it felt like it can't accelerate and it takes so long to reach 110kmh. Now, easily done. It's almost a completely new bike. The performance before was underwhelming, even coming from my old bike and EX5. And it just cost me RM300, labour included. But fuel consumption hehe..not so sure how much increase. But still, if got increase definitely worth it for the performance difference.

    1. Pray tell which carb you use and where you got it done. RM300 is value for money. :) Many thanks for sharing. While I am not a performance junkie, anything to "improve" on the ride is good :)

  10. I am from malaysia too..have a keeway rkv 200
    The engine is same for tx tx rkv i think
    Where did u buy the aquarium filter from?
    I tried to find it in DIY couldn't find it there.
    And about the carburettor.which one to use...i recently fitted it with 150cc honda rs150 one...its good but not that as can u suggest a good carb

  11. Hello tristupe I'm selven from mauritius Island I have a keeway tx 200 I would like to do some modification because it does only 125kmph and I want to improve its performance what carb do you recomend

  12. I think you may be able to obtain a little power by cutting away the section in the air box intake= the middle bit of plastic that creates the 2 sections.
    Perhaps even cut section out to have one less curve in the air intake duct system


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