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I got a new back tire for my ST4 and finally installed it on Friday. First ride revealed some less than desirable throttle responses and theorizing on a rich mixture I removed the snorkels from the airbox (I'm guessing I more than doubled the input as the holes in the airbox are much larger than the snorkels themselves) . The difference is monumental but I think there's still room for improvement. Are there other less than permanent (and gradual) mods that can be made to the airbox cover that might help or should I just start cutting?
 

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Discussion Starter #2
after digging further

I found the following on Sigma Performance Ducati

"The first confirmation was that the Ducati design department still suffers from 'Supermono airbox disease'. We took the airbox top off and promptly found a bunch of power, all the dips and bumps in the curve ironed out. Torque likewise was up, at 6000 rpm we had a near 7 ft-lb. improvement; 14% more than standard. We don't like impractical improvements and leaving the top right off was going to make a bit too much noise and would leave the filter open to getting wet, this is a street bike after all. We decided to try and modify the intake system for the best balance of noise and power.

Taking the airbox intake snorkels out upped the noise but made no difference to the power. Two extra 25mm holes in the back of the top got us a couple of HP at the top, but we were after the mid range, progressively stripping out the back of the airbox top got us nearly everything we wanted. 5 bhp came from just that mod all the way from 4500 to 9000, a couple of hp for the last bit, the only loss to the completely open box being 2 to 3 hp from 8000 to the redline, we got all the torque improvements up to 9000 too. If we have an ST4 race I'll worry about the last bit. "
 

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Find a DUC event, or maybe get chummy with the repair tech at your local shop. See if you can "borrow" one of the filter frames (lid eliminator). That should allow you to feel the improvement, and sample the noise increase.

FWIW, I lopped off the rear side of my airbox on my ST2 many years back. That filter lid is now on my ST4S, and it it made a noticeable improvement in midrange punch, and top-end.
 
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I got a new back tire for my ST4 and finally installed it on Friday. First ride revealed some less than desirable throttle responses and theorizing on a rich mixture I removed the snorkels from the airbox (I'm guessing I more than doubled the input as the holes in the airbox are much larger than the snorkels themselves) . The difference is monumental but I think there's still room for improvement. Are there other less than permanent (and gradual) mods that can be made to the airbox cover that might help or should I just start cutting?
Start cutting,:eek:,,start :think:
 

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Discussion Starter #5
Cut it off...

cut it all off. I followed the suggestions and cut a very large section of the airbox lid and found like Stick a much needed midrange punch. The bike certainly is a lot louder but the overall rideablility is more than worth it.
 

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Mr Leakered
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After an entire winter of commuting in a lot of rain and a bit of snow, I can say that the chopped lid is not affected by weather. The intake tracts look great right down to the valves.

Keep in mind that there is nothing really keeping the rain out with the lid as stock.

Also, for me there was only a slight increase in noise at idle and when the engine was unloaded. 90% of the increased noise is only on accelleration. I found that a set of slip-on (or a bit of coring) nicely complement the airbox mod.

All that was said above about the power delivery improvements was completely true for me. The biggest advantage I found was that the very bottom of the power band was much more usable when chugging around. 2,500rpm does not lug in around-the-town riding.

Have a good one.
 

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This sounds like a great, and cheap, fix for more mid-range power. Photos of the modified airbox would be a great help!
 

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This sounds like a great, and cheap, fix for more mid-range power. Photos of the modified airbox would be a great help!
http://www.ducati.ms/forums/showthread.php?p=51893&highlight=airbox+picture#post51893

See the link above although I pulled the snorkels out too 'cause that's the way it's done in the DP kit.

I'm not certain if it's advisable to just open the box without compensating for it in the fuel map with an aftermarket chip, though. I would think it would run lean without some adjustment. I only did that to mine AFTER I put the DP chip in the ECU. Any experts care to comment?
 

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Mr Leakered
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Sorry. I'm no help here since I chopped my lid a month before a valve adjust. I also added a DP ECU found on ebay for $40 and did some exhaust mods. I did check the TPS and TB balance after the valve adjust, but I don't have the equipment to check the CO.

Some folks say there are no mods if you do the airbox or add slip-ons but not both. Some will say to tune the hell out of it. I'd say watch your MPGs and listen for lean popping from the exhaust when coasting or engine braking. If either of these change, then some adjustments are needed.

Have a good one.
 

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Discussion Starter #10
My bike was sluggish and popping without the mods so I figured I couldn't do any worse and I could always use some aluminum tape to reinstall the piece I cut out at any time. Like tonered I found the low end to be so much more usable I doubt I'll ever go back. I'm still curious as to why the bike started misbehaving as much as it did after I installed a new back tire. I guess the new tire added enough circumference to raise the gearing just enough to cause the issue.
 

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Mr Leakered
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It is tough to say what caused your first issue. It is unlikely that a rubber change would cause any kind of fueling issue. Although, it wouldn't be the first example of two parts changing function at once on a Duc. ;)

Just the other week when I installed some new plug wires, I wanted to check that both cylinders were firing before putting the fairings back on. Funny enough, the bike was a no-go. I ended up tracing it to a fouled starter switch. It crapped out on a beautiful day after being through a very crappy winter. Go figure. This was may best experience EVER working on an electrical issue (I didn't even feel temped to dig out the big hammer).

BTW, I raised my rear suspension with an older, but not worn out, tire(Met Z6). After installing new Diablo Stradas, the rear rubber stays in contact with the ground when on the centerstand. The is most likely due to the increased diameters on the front and rear, but an increase at any rate.

Good luck.
 
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