Catalytic Converter

[rtking]

Originally Posted by 2LZ

Here ya go...
"Manual transmissions lose 15%. To determine rear whp, multiply the base horsepower by 0.80 if you have an automatic transmission and 0.85 for a manual transmission. Example: 250 hp x 0.80 = 200 rear whp."

So a rear wheel HP on rtkings bike at 22.5 would come in at about 25.8....which is better than spec just by changing a pipe at the time. I'm curious to see how he thinks the breather helped.

You nailed it, 2LZ. I did a write-up in another link here:

http://chinariders.net/showthread.ph...highlight=dyno

I was using a conservative 10% drivetrain loss instead of 15%. But the fact is that the dyno is rear wheel, and the engine is delivering the advertised horsepower.

About performance... the muffler probably frees up a little (maybe 1 hp?) which is tough to feel. But the throttle response is good with the aftermarket muffler.

With the K&N filter (and this is based on riding around the parking lot near my house), the bike feels like it's breathing better and is more responsive. I don't know how much of that is wishful thinking vs. actual performance. My "test" will be next weekend when I can get in a ride and see if there's any top speed and drivability improvements.

In terms of the part - I want to re-measure the throttle body as this filter (K&N part number RC-1290, 48mm inside diamter) is a little big for the throttle body. I think the cone filter the Grom riders are using (K&N part number R-1100) might work better with its 43mm inside diameter. And whatever filter is being used, having a 10 degree (or so) bend is necessary to clear the airbox (which I sealed off with foil tape for this experiment.)

Bear in mind that in this location, the filter will be exposed to a lot of dirt and moisture. I plan to purchase a Filterwear Pre-Filter for the cone filter to help filter dirt/dust and water. I'm also planning to use some aluminum tubing to extend the filter into the stock airbox (and make some more breathing holes) to see if that makes a difference.

Like I wrote... I love to tinker.

[2LZ]

Originally Posted by rtking

You nailed it, 2LZ. I did a write-up in another link here:

http://chinariders.net/showthread.ph...highlight=dyno

I was using a conservative 10% drivetrain loss instead of 15%. But the fact is that the dyno is rear wheel, and the engine is delivering the advertised horsepower.

About performance... the muffler probably frees up a little (maybe 1 hp?) which is tough to feel. But the throttle response is good with the aftermarket muffler.

With the K&N filter (and this is based on riding around the parking lot near my house), the bike feels like it's breathing better and is more responsive. I don't know how much of that is wishful thinking vs. actual performance. My "test" will be next weekend when I can get in a ride and see if there's any top speed and drivability improvements.

In terms of the part - I want to re-measure the throttle body as this filter (K&N part number RC-1290, 48mm inside diamter) is a little big for the throttle body. I think the cone filter the Grom riders are using (K&N part number R-1100) might work better with its 43mm inside diameter. And whatever filter is being used, having a 10 degree (or so) bend is necessary to clear the airbox (which I sealed off with foil tape for this experiment.)

Bear in mind that in this location, the filter will be exposed to a lot of dirt and moisture. I plan to purchase a Filterwear Pre-Filter for the cone filter to help filter dirt/dust and water. I'm also planning to use some aluminum tubing to extend the filter into the stock airbox (and make some more breathing holes) to see if that makes a difference.

Like I wrote... I love to tinker.

Thanks for the excellent info rtking!....and it seems we are co-tinkerers... ;-)

In all honesty, it's the throttle response, under load, that I'm more interested in clearing up, not just HP gain. Seems anything under 5k at all...and it's "Bawwwwggghhhh" until it really winds up. The 13 tooth helped but it just sounds so choked up sometimes. Almost like an old Honda 90 on steroids.

[rtking]

Originally Posted by 2LZ

In all honesty, it's the throttle response, under load, that I'm more interested in clearing up, not just HP gain. Seems anything under 5k at all...and it's "Bawwwwggghhhh" until it really winds up. The 13 tooth helped but it just sounds so choked up sometimes. Almost like an old Honda 90 on steroids.

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.

[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.

[2LZ]

43mm....got it! Awesome, thanks.

Well......In the interest of public service (gasp, choke),...in all honesty, I just couldn't wait, I ended up ordering a new muffler for the RX3 yesterday afternoon. I'm not going to say what I got yet...and it's going to be a crap shoot regarding mounting.....but it measures out correctly for can length/pipe, etc....so once the TT is done, I'll be chasing this next. Rest assured it's not a pricey one like the Akropovic or a Yoshi or anything....but it was worth the gamble in my book for a beta test.

rtking, I'm just so impressed with the throttle response and how your bike has seemed to come to life in your videos....especially with that super tall gearing you have....I had to do something. It's all your fault man!!! ;-)

[SeerAtlas]

no offense to either of you guys, but in my lifelong experience, unless something is incredibly restrictive from the get-go, increasing your front end breathing only helps at the point something is restrictive at the first place, i.e. at or near full throttle/revs. Hard to imagine that the stock setup is choking the engine at lesser flow rate settings.....we'd have heard about the design engineer's execution......

[2LZ]

Originally Posted by SeerAtlas

no offense to either of you guys, but in my lifelong experience, unless something is incredibly restrictive from the get-go, increasing your front end breathing only helps at the point something is restrictive at the first place, i.e. at or near full throttle/revs. Hard to imagine that the stock setup is choking the engine at lesser flow rate settings.....we'd have heard about the design engineer's execution......

No offense taken, SeerAtlas! :-) We all know you're an ornery ol' cuss! ;-)

Simply put, I like pod filters. Zero chance of obstruction, even breathing and easy to service....and if you notice, I like to service my rolling stock. It's how I "play". No other real reasons. If they help with the breathing over the stock box, bonus!