Air Box down tube removal

[yhet43]

Hi guys! Has anyone tried removing their airfilter box downtubes? It's those two tubes at the exterior that points down towards the engine. I removed mine in hopes of getting more power from my bike, especially in high rpm's...seems to have worked...my bike runs much stronger than the time i had those tubes on. The down side i just see at the moment is, my airfilter will be more subjected to frequent cleaning due to the open holes wherein dust and insects can now easily get in.

Has anyone tried this? Would appreciate any feedbacks on it's effect on your bikes performance. Thanks!

[PeaceKeeper]

Actually, I found that removing the tubes on mine caused a vacuum in the airbox over 45mph. Stand-still throttle response was unchanged. I still had the rubber "heat shield" in place between the head and wiring/tubes/airbox, but who knows if it was in the exact right spot. Those things are a royal pain. Cover plates were off.

Of course, finding this out at night on the way home from doing this modification sucked. The bike literally began to stall at highway speeds. I figured out what was happening by placing my hand in various places in the front of the bike, blocking airflow in/out of certain areas. I rode the entire way home with one had pasted to a certain spot near the side cover mounts, which allowed my to maintain 55mph or so, but only just.

I have since learned to not screw with the tubes/heat shields/side covers. Although I have cleaned out some of the "junk" inside the airbox.

I am betting that modification of the entire intake system(shields, side covers, etc) may net you a gain in the end...  But all that stuff was put where it was for a reason.

IMO, get a higher flowing air filter and use the stock setup, or ditch the entire thing and use clamp on filters.  Anything in between risks screwing the whole thing up.

[clarkdw]

I have since learned to not screw with the tubes/heat shields/side covers. Although I have cleaned out some of the "junk" inside the airbox.

I am betting that modification of the entire intake system(shields, side covers, etc) may net you a gain in the end...  But all that stuff was put where it was for a reason.

IMO, get a higher flowing air filter and use the stock setup, or ditch the entire thing and use clamp on filters.  Anything in between risks screwing the whole thing up.

+1

"Seat of the pants" dyno tuning and modifications of the air intake system on the CB-1 is much more likely to give you nagging problems of flat spots and speeds at which the bike runs like shit than actually gain you any performance. Even hours spent on the dyno working on the airbox and such are totally wasted as soon as you start moving and rearranging the airflow. Unless you are willing to spend as much as Honda did figuring out what works you might as well just enjoy the wonderful job that their engineering staff did to the stock bike. Much of the misconception about how some mods help stems from the fact that almost anything you do will make the induction noise quite a bit louder. Sounds faster and that makes it feel faster but without a LOT of very careful testing, how can you tell if it has helped or hindered??

[a_morti]

I've fitted a uni-foam filter element and removed the baffles from inside the airbox. Not sure about performance gains/losses, but it does sound a bit nicer.

[yhet43]

thanks everyone for all the input. I must admit, it did "feel" a lot faster, but i somehow felt some drag or hesitation on high speeds. It's always good to ask around eh? ...I plan on putting back the tubes and just remain satisfied that my -1 is doing a great job as it is.

[stussels]

i remember before i rejetted my cb-1's carbs i tried removing the snorkels.  it ran terribly.  especially with crosswinds.  after rejetting though i tried again and it really woke up the jet kit.  been running it that way since.  so id leave em be with stock jetting and pull em if you rejet.

[ptlcb1]

+1 to all the above.  Now I'll add my two cents...   No snorkels on my air box.  Replaced paper filter with a two stage foam filter.  Jet kit. After market exhaust.   All these mods were done on a dyno with fans.  This is the only way, in my opinion, to get "happy" gains from any mods on the intake side. 

As was stated earlier, when you change anything about the stock set up, you are upsetting the balance that Honda developed for the bike.  Sure the route of those snorkels make no sense.  They only seem to suck hot air off the top of the engine.  Common sense to me is that, to make power you need the intake air to be cool, not hot.  An option if you want the bike to, either be faster or quicker, is to change the sprockets.  Without touching the front sprocket, if you go smaller in the rear, you will lose some acceleration and gain some top speed.  If you go larger in the rear, you will gain acceleration but have a lower top speed.  Just remember, you can only go so far with the size of the sprocket, whether larger or smaller, because of the length of the chain, and the chain tension adjusters. 

I use to run a 45 tooth rear sprocket at a particular track, because it was a tight track, so top speed was less important.  I had a second chain that was longer, to use with the 45t.