Made the decision to take advantage of the free HP and torque. It's a bit more noisey however it did gain more punch and feels much better. To be noted I have a stock exhaust with the Afxied and the temp spoofer.
You should notice quite an improvement. The tiny stock air horns don't breath well. The headers without the cat should compliment it all very well.
Just came back on a high sprinted street ride with all bigger GS bikes. Mostly pretty twisty stuff so it was a lot the rider's ability. None of the big bikes got away on any straights and I can report now with the open air box it feels like much better top end as well as torque. So with the open air box set up I have decided to balance out the exhaust with a Akrapovic slip on exhaust and see how it goes.
Yes you can drill 1" - 1 1/4" holes in the front of the top air box cover as pictured in post #1. This opens up the airbox to breath big time.
What about the risk of water leaking in from the top tank panel? Those panels do not look very waterproof to me. The battery is also under that panel and I haven't had any shorts, so I guess rain riding should be okay. Now that I think about it, if you dump the bike in a water crossing, you would have been screwed without the mod, and slightly more with it. How is the intake sound after the mod? Does it get rid of the sewing machine feel of the stock bike?
I think the rain might be okay as the holes face forward and there is a lot of stuff in the way before anything can get that far back. If you drown the bike in a water crossing your screwed holes or no holes. It removes the sewing machine feel and the several false power bands. You can hear the growl of the intake begging the next step being the a slip on exhaust or complete header set up. However I went with a slip on and decided it should be fairly balanced keeping the cat in the stock headers.
Snks, Excellent job with the mod! If you look at my build thread http://advrider.com/index.php?threads/an-800s-rebirth-the-build-of-mechanico.1030354/page-13 there is definitely some gains to be had with letting the motor breath more on the intake side. Yo can see on the dyno charts there is significant gains by removing the air box and filter. So one can conclude the stock intake does have some restriction. However I might question the location of where you added the extra intake ability. There is a good reason the stock intake "horns" extend forward. They can get cold air from in "front" of the engine and radiator. Cold air has significant gains as well for performance. But the temp of the air were you drilled the holes might not really be that much warmer or the gains in flow out-weight an extra few degrees of air temp? Would be interesting to put a cheap kitchen thermometer with a remote sensor in two locations: Tape in on the intake of the stock intake horns on the side of the air box Tape it near the holes you drilled in the air box cover Then tape the LCD screen head unit on the top of the air box cover and go drive on a stretch of road at a fixed speed and note the air temps for each configuration. I would hope you see no more than 10 degrees F difference. Or the heck with it, if it feels better and works, ride it!
Yes I have read some of your thread which is very cool. After riding the F800 for a while now the usual did occur to me about how lean they run stock. After successfully curing the Lean running with an Afixed the next step was to open the intake like any bike I have owned for 50 yrs. The horns are way too small even for a 250cc bike. Your idea of a new airbox and tuned runners toward cool air is great. However a might bit consuming but as mentioned cooler in more ways than one. I took the quick way. The air is likley warmer than stock. However the power gains over stock are huge and the false little power bands are gone. So yeah unless I feel like I had a need to visit the dyno room to do something that my seat of the pants isn't telling me I'll just run it. Please let us all know if you come up with a kit for your air intake set up.
I was tempted to do this, but as an experiment I just pulled the 2 rubber gaskets off the ends of the filter cover. Same effect, feels great, sounds great. AFxied > Boosterplug I did a bunch of fluid dynamics and flow velocity work to see if there was any point in changing the design of the intake horns... There isn't.
So I took the plunge and as per the OP drilled 3x1" holes in the air box. I just got back from a 5 hour ride mainly off road with some highway there and back. What I have noticed. A definite improvement in power. It sounds better. The throttle is a bit more snatchy at low rpms. Fuel mileage has remained the same as per the computer. My arrow slip on has a bit more 'burble' and sounds more throaty. In general it feels as though the bike has woken up so to speak. It feels more eager. I recommend this mod! The bonus is if you don't like it plug the holes and carry on. I'm happy. Icky
I did this a few years ago on mine but drilled the holes on top. Works better and never any problem with rain. If you do this and change to\\your mind, You can tape over the holes or get a new part. When I did mine, the part was about $10 which really surprised me.
I just did this last night and am stunned at how much of a different it made. I guess that was just want my Leovince exhaust needed at the other end.
I just installed a Akrapovic slip on exhaust and it sure didn't make much of a difference. Opening the air box makes a big improvement, exhaust not so much. I tried it with the decibel killer baffle and it's too quite. Without it too loud. So I will cut the baffle in about half or so which should be a good compromise.
Pulled this funny looking restrictor out of the front of the Akrapovic baffle insert. It looks like it belongs better on a champagne bottle than in the exhaust. Fixed now it runs very well from bottom to top.
