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Discussion Starter · #1 ·
Can anybody tell me why there are a couple of servo controlled flaps at the front of the airbox?Just my TNT is running far too rich (loads of black smoke+flooding when cold) and I put it down to these flaps not opening properly.Has anyone removed them completely and if so did it have any negative effect?It seems to me the more air you can get in the airbox the better.Am I wrong?
 
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Discussion Starter · #2 ·
I have removed the flaps from the airbox (and fitted a K&N air filter) the servo moves the flaps as well as the exhaust power valve so if you remove the flaps you have to modify the servo cable bracket a little to stop it twisting…….the flaps are there mainly for emissions and in my opinion they do reduce the airflow significantly. I cut the whole bottom of the airbox out and formed a scoop to increase airflow and as mentioned also did away with that pathetic foam air filter which doesn’t stop anything >:
The last 6 weeks I have been running with a broken power valve cable (3rd time its snapped) I only notice its not connected when plodding at 30mph ish speeds where it is a little lumpy (the valve defaults to fully open)…………. but the plus side is it doesn’t come in with a sudden surge at about 3500rpm which can be scary when your trying to exit quickly & smoothly from a deep corner. :eek
Over the winter I will fix the cable properly and possibly fit an override to the servo so that I can keep it open all the time should I want to........... another thing to look at is the servo there is a hole on the end plate and if water gets in it can make the servo stiff so it doesn't open/close properly I squirted oil in the hole to lubricate, which then made the valve turn gritty :eek: had to strip it and give it a good clean to get it working again.
 
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Discussion Starter · #3 ·
Thanks for that.Does your bike pour out black smoke at standstill if you rev it hard,or did it before your airbox mods?
Thanks again
 
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Discussion Starter · #4 ·
airbox flaps

If your bike is blowing black smoke, you either have a failed Throttle Position Sensor (TPS) or you need the idle CO adjusted with the hand-held Axone tool.

The flaps do not make it run rich, even though on my race bike I took them out and opened up the air intake scoop by 100%..... my bike ran terribly lean and missed & hessitated until I got Benelli to send me a special race ECU map and I closed off 50% of the air intake.
 
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Discussion Starter · #5 ·
Re: airbox flaps

Johnny O, I measured CO's before and after modifying the air box there was a noticeable difference, pointing to the air box mods definitely leaning out the mixture (which agrees with what you also found) I re-compensated by fitting the pcmIII……..after calculating the engine intake air volume and then the open area of the standard filter box with the flaps fitted the calculated pressure (resistance) was well over 1000pa (ideally it wants to be lower than 250pa) which means there has got to be a noticeable effect on the engines power output……. if you go to K&N’s web page you can put in the engine specifications and it will calculate the minimum filter area (K&N pleated filters) that is required, and you will see that this also proves the standard airbox configuration doesn’t let enough air in.
It really does look like the air boxes on the TNT and tornado have been designed to suit the space available not what the engine really requires.
 
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Discussion Starter · #6 ·
Re: airbox flaps

can u describe precisely what u did to the airbox,, if someone else wanted to do the same,, and what is the power increase. u got out of it,, and want to we need to do a good job,, the kn filter,, then the pcIII.. but how to turn the PCIII...

i always asked myself,, is there 2 different maps , on the tnts,, with the power switch on or off.. how does it works in this case..
 
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Discussion Starter · #7 ·
Re: airbox flaps

Thanks for your tips.My bike is now very hard to start from hot or cold and very hard to ride below 3500rpm,stalling often and bellowing black smoke leaving black soot all over the number plate lamp and indicators.Is benelli the only place to obtain a TPS,just it take weeks to get parts from them.
 
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Discussion Starter · #8 ·
Re: airbox flaps

I believe the TPS is made by BMW, but I don't have a part number for it. If you find out what it is, please let us know.
 
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