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Discussion Starter #1
I had a few inquiries regarding removal of the secondary throttle plates so here's what I know and don't know. I don't know all of the details so your results may vary. The secondary throttle plates are supposed to smooth out power, tame the ponies. Operation of the secondary throttle is controlled by the ECU and will set a fault if you simply disconnect the harness. To remove the plates: remove the air cleaner housing then remove the screw from each plate. The plate will now slide out of the throttle body. From my limited research some people say there's hesitation as a result of the inrush of air now available, while others have not experienced any problem. Those that did increased the fuel. My plates have been removed for the last 6k miles and the bike defiinitely has more giddy-up. How the change effects each bike is not known since there hasn't been any discussion for the 900. My setup: relocated air inlet beneath the idle adjustment; replaced paper air filter with 60ppi Unifoam; debaffled; Fi2000r.
 

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Where abouts in the mod changes did you remove the plate?

Had you already done the changes to the air cleaner?
 

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I've already poked holes (4 ea.) in my baffles, but haven't removed them. I haven't done any mods to the intake. Since the change to the exhaust is slight, do you think removing the plate would force me to need a fuel controller?
 

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So thats what the surge is when cracking the throttle hard, is these plates opening up.I can almost feal the tire try to break loose in each gear @ a sertain rpm(no tack sucks).I wonder about putting holes in the plates to smooth this out & bring on the power sooner.
 

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Discussion Starter #6
Helek: The 900's seem to run a bit rich from the factory since the fuel system is open loop. I'd remove the plates. If the bike stumbles at low rpms when opening the throttle hard you'll probably want to put the plates back in. I doubt the quick lean condition would hurt anything but I don't know about driveability.

XC: No tach - first vehicle I've owned without one but the price of a tach is not reasonable since I have other toys to feed. In my net travels I saw one person (a Suzuki) that had drilled six 5/16 holes. If they're already off for drilling why put them back in you're making that many holes? I think the holes would really make a mess of the incoming air. Breaking the tire loose is what first got my attention. When I first removed the plate I short shifted and smacked 2nd gear. The 200 Avon didn't break loose but it wanted too - doing that when the bike wasn't point straight got my attention real fast. The 900 is by no means a rocket, my first cruiser since coming from sport bikes, but it does have a new attitude.
 

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I had a few inquiries regarding removal of the secondary throttle plates so here's what I know and don't know. I don't know all of the details so your results may vary. The secondary throttle plates are supposed to smooth out power, tame the ponies. Operation of the secondary throttle is controlled by the ECU and will set a fault if you simply disconnect the harness. To remove the plates: remove the air cleaner housing then remove the screw from each plate. The plate will now slide out of the throttle body. From my limited research some people say there's hesitation as a result of the inrush of air now available, while others have not experienced any problem. Those that did increased the fuel. My plates have been removed for the last 6k miles and the bike defiinitely has more giddy-up. How the change effects each bike is not known since there hasn't been any discussion for the 900. My setup: relocated air inlet beneath the idle adjustment; replaced paper air filter with 60ppi Unifoam; debaffled; Fi2000r.
With the plates removed, do you still have a fast idle at cold startup?
 

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Discussion Starter #8
No effect on the fast idle, removing the secondary plate just lets air in the throttle body all of time. It's annoying at times but hasn't been on the top of list for things to tinker with. One day I'll look in the shop manual. Someone said you can firmly hold the throttle closed and fast idle will go away. I tend to think something may break so I live with it for now.
 

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Discussion Starter #10
GD: Remove the airbox and remove the rubber insert. Make a pattern of the opening and transfer it beneath the idle screw - it's not a perfect fit due to lack of space but once you put the rubber back it you can't tell. I used a Rotozip to cut the opening. I blocked off the old inlet with a scrap of aluminum gutter and 2 pop rivets.

 

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this mod only for stock intakes or something to do with a bak too
The secondary throttle plates are motor driven and modulate similar to CV carburetors with diaphragms and needle valves. I found that after removing my plates that the bike ran lean on the low and lower-middle rev range. Once I richened the PCV in those ranges the bike felt peppier with more pulling power. Without the plates the feeling of a power lag during the first few seconds of 60%-100% throttle is now gone. The power is now more predictable.
As a side note, the same throttle shaft also controls a small metal disc shaped like a half moon that's located outside the throttle body opposite the drive motor. That disc controls the fast idle during start up. I didn't like the RPM during fast idle start up so I modified the disc so it doesn't open the primary throttle plates quite so much.
 

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I don't know how the bak mounts but all you need to do is remove enough of the BAK to see the throttle body and then remove the two plates, each one is held on with one phillips screw each.
 

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If the CPU, or another glitch in the fuel system just starts dumping in extra fuel, what keeps the engine from racing to its extinction from having a wide-open throttle?:eek:
 

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If the CPU, or another glitch in the fuel system just starts dumping in extra fuel, what keeps the engine from racing to its extinction from having a wide-open throttle?:eek:
pacomutt, the primary throttle plates and shaft are untouched. Only the secondary throttle plates, which are located in front of the primary throttle plates, are removed.
 

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pacomutt, the primary throttle plates and shaft are untouched. Only the secondary throttle plates, which are located in front of the primary throttle plates, are removed.
OK, thanks. I was just having an image of a diesel engine(no throttle) with a runaway fuel injection.
 
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