Catalytic Converter

[2LZ]

Originally Posted by rtking

I understand. Sometimes the engine doesn't really spin up as quick as I think it should as I accelerate from a stop and I end-up stalling the bike. I think the same issue as you describe...which might be restriction in the intake.

I still haven't had the time for a longer ride, but I did take the bike for a bit of a ride around the neighborhood. Thinks I've noticed with the K&N filter:

• The hesitation/sluggishness from lower RPM is reduced or gone. I'd favor the word "gone" as the bike surprised me with how tractable it was at low RPM riding. Gone was the "buck-boarding" hesitation/acceleration I had when riding right above idle. (I ride at low RPMs around my immediate neighborhood.)
  
• There's way more induction noise. Not surprising in the least since there's only cotton and iron mesh between the throttle body and my ears. But the engine now sounds more like a two-stroke than a refined four-stroke single. I actually like the sound... but ask me again in a few days when I put some freeway miles on it.
  
• The bike pulls quickly up the RPM range and eagerly into redline. I'm again surprised, especially since I've got the 42T rear sprocket (to drop RPMs on freeway cruise.) I have less torque multiplication, but the bike did a nice job of accelerating through 1st, 2nd and part way through 3rd. I want to say it accelerated faster than with the stock air box, but I can't be sure since it's been a few weeks since my last ride (breathing through the stock air box.)
  
• I can actually feel (more-so than before) the power increase around 5,000 RPM now. It's slight, but it's there. With the stock airbox, there was a less pronounced transition as the engine "came on cam."
  

Before anyone goes out and tries this on their own, the standard caveats applies: You are doing this on your own no warranties expressed, implied, yada, yada, yada. But it's important to note that the filter is exposed, so no dirt riding (at least, not beyond a few hundred feet), and certainly no going through deeper puddles. The Filterwear cover will help filter dirt and repel water, so that will help in the short term.

The longer term test (again, when I have time) will be to run an aluminum tube from the throttle body and through the stock rubber boot to the K&N filter, then cut holes in the stock air box to promote better breathing but using the bottom of the airbox to help keep water and some dirt out.

Fantastic information, once again rtking. Thank you!

Oh man....with the TT250 mid stream of the project...now I'm chompin' at the bit at getting a pipe and breather for the RX3! Dangit.......

Did you re-measure the intake and decide on a perfect fit filter or did I miss that part? I'm not too concerned about off-roading and the filter being exposed. We do have a dirt driveway but it's still a drought. The closest body of water is our 12' Walmart pool. I do like the idea of burying it inside the stock airbox though and boring holes in it or getting the sock cover for it, especially for washing.

[rtking]

Originally Posted by 2LZ

Did you re-measure the intake and decide on a perfect fit filter or did I miss that part? I'm not too concerned about off-roading and the filter being exposed. We do have a dirt driveway but it's still a drought. The closest body of water is our 12' Walmart pool. I do like the idea of burying it inside the stock airbox though and boring holes in it or getting the sock cover for it, especially for washing.

LOL - well, if you do what I did (purchase from EvilBay), there's about a week of shipping time that will allow you to finish the TT250. (Which is a bike that I'm looking at keenly!)

The throttle body outside diameter is 43mm. It looks like the inside diameter of the throttle body is 38mm, but it's the outside diameter we need to focus on. The filter I bought is 5mm too big, but the radiator clamp does a fine job clamping down on the filter and ensuring a tight fit. I like that this filter has a 10 degree flange angle so that I can pitch the filter down (to clear all the stuff above where the air filter wants to be.

The filter the Grom riders use is a R-1100. It has the correct flange inside diameter of 43 mm, but it has a 40 degree flange angle, and I think that's just a little too extreme for our use. Looking through the rest of the K&N catalog, I think the R-1080 might work, but it has 0 flange angle, so there may be some contact or difficulty getting the filter to sit square on the throttle body.

I guess that's my long winded way of saying that I'll stick with my RC-1290.