Ducati Sporting Club UK > DesmoDue Race Series > DesmoDue - General Questions and Chat > M620 & u/seat exhaust

[skidlids]

Originally Posted by bradders

and weight is important...and better to keep weight low to the ground isn't it?! altho I cant have my shortyy can

Some people don't mind a high centre of gravity as the bike rops on to its side easier, just takes more physical effort to pick it back up, so things like chicanes become harder work, especially towards the end of a long race at the end of a long weekend.

Throughout the Moto GP era there has been a real focus of getting the centre of gravity in the right place and centralising the weight. As nobody likes to much weight seesawing back and forth


As for Silencers your trying to dissipate a fast moving sound wave, fast as in travelling at the speed of sound, so how do you get it to dissipate enough before it reaches the sound meter. I would go for giving it a fairly long not to restrictive baffle say 450mm long with 50mm diameter as the alternative is a short restrictive one say 200mm long and 35mm diameter, equivalent to some of these so called race cans with a dB killer fitted

The Austin Racing system on the RSV4 I had off Dallas is quoted as
102/103 with 35mm insert 104/105 with 50mm inserts and 108dB without and thats all with a new silencer and where the insert drops in to the link pipe prior to the silencer. So if you want to insure you pass the Noise test you would probably have to be running with the 35mm insert all of the time .

Be my guest to run what yo want, but you'll probably end up in the race office complaining that you failed just like one guy did at the Final Hottrax meeting at Snetterton 200. When the only way to get his R6 through was to fit a dB killer

I helped Sound Check 40 bikes that weekend and they ranged from 98 dB up to 105dB on our record sheet. Hopefully those that were right on the limit will be repacked over the winter ready for next season

[chris.p]

One other thing to remember when choosing the length/diameter of a can is what it does to the performance of the bike.

By changing the internal diameter of the pipe and/ or the length of the pipe will effect the bhp and torque curves of your bike.

Shorter pipes give more top end at the expense of mid range and visa verser.

What may look good and cool on the bike could be robbing you of power where you need it most.



Chris

[bradders]

Originally Posted by chris.p

One other thing to remember when choosing the length/diameter of a can is what it does to the performance of the bike.

By changing the internal diameter of the pipe and/ or the length of the pipe will effect the bhp and torque curves of your bike.

Shorter pipes give more top end at the expense of mid range and visa verser.

What may look good and cool on the bike could be robbing you of power where you need it most.



Chris

good point Chris, I remember Senna saying he changed his at the dyno as the slightly longer cans gave a bit more oomph

[skidlids]

Longer ones usually give it a bit less, in Kev's Case I think the Contis worked out as a longer internal silencer than the exhausts he changed to

Did the same with Dallas 2010 Class A bike, had to fit a longer can to drop the BHP a bit to get it within the class limit, but gained some midrange from the change