Ducati Sporting Club UK > Model Specific - Discussion, Technical Problems and Help > Sport Touring: ST4 / ST3 / ST2 > airbox mod

[Glyn]

had a flat spot on the st for ages tried all the normal stuff
with no joy
tapped up the couple of extra holes id put in the air box lid and hey presto no flat spot
i know this is a mod a lot of st riders do, so any body else had this problem with it
i take it that it could be sorted by adjusting the mixture,what do you think

[TP]

Nice one Glyn

That can't be your bike in your avatar though, can it? It's got a seat on it!

[Glyn]

well here my seat hasn't got a bike with it

[rockhopper]

Thing is though glyn, you can't adjust the mixture, you need to change the chip in the ECU.

[TP]

Originally posted by Glyn
well here my seat hasn't got a bike with it

[Glyn]

Originally posted by rockhopper
Thing is though glyn, you can't adjust the mixture, you need to change the chip in the ECU.

well thats silly
i'll just leave the holes taped up then
then again maybe not. the old flat spot line is one of my favorites for when jools hoons past me

[KeefyB]

Sounds like the old girl was running with a lean mixture.Taping the holes up has richened it up again.
You only really need to open up the airbox if you are using race cans and uprated chip.

[moozaad]

I'm being good at this today!! I disagree!!!


I've seen a couple of dyno results (see richards ducati ST FAQ and sigma performance site) that show putting holes in the airbox straightens out the power curve without needs any adjustments.
Every bike is different and it may not be true for all. The only real way you'll find out is to dyno it with and without the holes.
BTW adjusting mixture to compensate is just a turn of a potentiometer next to the ECU

[Edited on 13-7-2005 by moozaad]

[Jools]

Originally posted by Glyn

well thats silly
i'll just leave the holes taped up then
then again maybe not. the old flat spot line is one of my favorites for when jools hoons past me

Hmmm...

Chance would be a fine thing. On our last ride out, when I was following you, I was closing up on you going into corners, getting the power on early, and although our mid corner speed was near enough identical your bike was pulling away from mine on the exit even though I had the taps wide open. So, misfire or not, your bike seems to have a strong engine for an ST2.

Me and Keefy were talking about this a week or two back and came to the conclusion that if two supposedly identical bikes come out of the factory at the same time, just as ours did (since they were supplied by the same dealer just weeks apar)t, then by pure luck one of them might come out with good compression, the cams pretty much dialled in and all the little production variables falling in line to produce a good engine whereas the next bike on the line might just get an average engine or a less than average engine. The difference between the best and the worst bike on any given day could be 6 to 8 bhp.

Having said that, my bike has DP cans, a JHP chip and eight 22mm holes in the back of the airbox lid. It might not be any faster for all that but it doesn't misfire and it sounds luvvveeerleeee

[Glyn]

Originally posted by moozaad
I'm being good at this today!! I disagree!!!


I've seen a couple of dyno results (see richards ducati ST FAQ and sigma performance site) that show putting holes in the airbox straightens out the power curve without needs any adjustments.
Every bike is different and it may not be true for all. The only real way you'll find out is to dyno it with and without the holes.
BTW adjusting mixture to compensate is just a turn of a potentiometer next to the ECU

[Edited on 13-7-2005 by moozaad]

there might be other factors but i have changed the plugs oil and fuel filters
nelly has checked out the throtle position sensor and that was o.k
big flat spot at peak power taped up holes and it's gone un tape holes and its back
as you say every bike is different and next time i'm up at nellys i'll have a word
i've got two holes in the lid tomorow im going to untape one of them!