Ducati Sporting Club UK > Model Specific - Discussion, Technical Problems and Help > 998 / 996 / 916 / 748 > Restrictors in air intake tubes?

[Totto]

Hum ,methinks mine might get accidently lost the next time i oil the filters !!

[Shazaam!]

Long answer:

Like sps955 says, the rubber restrictor annulus on the superbike inlet runners are designed to reduce air induction noise to meet US EPA (and Euro?) limits. These are not inlet restrictors designed to limit performance like those used recently on some Japanese bikes to meet maximum speed limits. The superbike blocks merely increase the velocity of the air as it passes through the device but reflect sound waves back to the engine inlet. Said another way, the pressure drop across them is very low as opposed to a high pressure drop created by a dirty air filter. Removing them increases the free air volume between the velocity stacks and the stock air filters which has the added benefit of a better throttle response (but no more power).

Short Answer:

Like weeksy says, if you take out the restrictor blocks you’ll get a nice intake growl.

[ben998]

Well, I removed them last night, rode in this morning. The instantly obvious change was the intake noise - much more of a growl than before. Not sure if I'll still be able to hear it once the stock exhausts are removed and the new ones fitted, but definately worth doing if it helps everything breathe easier.. not to mention the huge weight saving

[Bianchi]

My 2001 996Bp bought new didn't have these rubber restrictors in.

I am informed that bikes destined for the USA market did, for the reasons stated by Shazaam.

[ben998]

Im pretty sure my '02 998 is a UK spec bike. It doesn't have any of the extra emission control equipment that a US destined bike would have and the Ducati delear that I bought it from was the supplying dealer and they confirmed it was a UK spec bike. Apparently some of the recent new 998's that have been turning up are US spec bikes that the dealers are having to modify to UK spec which is apparently quite a bit of work.
.

[Totto]

Anyone mailed JHP/Ducati for the Official version ?


Just pulled mine out today & went for a ride
The throttle response is deffo better , Plus she sure does Growl now !

[Edited on 29-8-2003 by Totto]

[Totto]

JHP say its OK to take them out ,won't make much difference & is best done with other mods IE pipes/chip

But the throttle response is improved , well i think it is anyway !

[paulk]

Originally posted by Bianchi
My 2001 996Bp bought new didn't have these rubber restrictors in.

I am informed that bikes destined for the USA market did, for the reasons stated by Shazaam.

Wierd that. My '01 996 Bip did have the restrictors in. UK dealer supplied and UK spec bike.
Fitted some of Ripsnortingvtwins carbon airtubes and a JHP undertank filter a while back and took them out. Couldnt get over the size of them!

[ben998]

My '00 996bp had them in as well. That was a UK bike supplied through an official Ducati dealer.

[pguenet]

Ben

Nobody seems to have picked up on that and sorry if I am stating the obvious - but since you don't have many posts, you might be new to Dukes- better to check than you making a big mistake.

When you removed the filters from the airtubes, I believe that you fitted an under-tank filter (such as ITG / JHP / etc).

Don't let the airflow completely free cos the bike does pick up some crap and this is going straight into the engine if there is no filter on the way.

Just imagine the dammage that a small stone could do to your top end... It did happen to me once on a GoKart (you don't have air filters in Gokart, that would restrict airflow too much) and it was a carnage in there.

Again sorry if there is stating the obvious but better to do so then leaving you with a totalled engine!!

Cheers
p