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

[skidlids]

Ron's Monster was the earlier type with the suspension loop, the 620 setup which is pretty much the same as 748/916 749/999 with its tie rod leaves even less room to get the pipework through, you would need to run it around the side like the 749/999 but the double sided arm isn't designed for it.

My can is a Harris can made for the stsyems they used on the GSXR750s they ran in World Superbike. The can itself is about 16" long.

Around 1996/97 the Noise regs changed to there current level of 105dB, one year everybody was using 14" cans the next they had all grown a couple of Inches. So getting a free flowing can to meet 105dB and getting the size down to 10" probably isn't going to happen. Reducing the diameter with a baffle will reduce the noise as it reduces the Gas flow.
Using a baffle for sound testing and then removing it for racing is basically cheating. When others are using a bike with a exhaust that restricts the noise level to 105dB it also has implications on the power available, so anybody using a free'r flowing exhaust making more than 105dB is not playing by the same rule book.

[bradders]

how big do you reckon then? And what size diameter Kev?

I'd guess Craig's weren't an issue because he had 2?

[Cranker V2]

im going to use an akrapovic like this with custom link pipe. Short, neat and tucked away - bit like my nads most of the season

http://www.ebay.co.uk/itm/AKRAPOVIC-MEGAFON-SLIP-MOTO-GP-CAN-TITANIUM-R6-2006-/270861141423?pt=UK_Motorcycle_Parts&hash=item3f109 505af

[skidlids]

That wont pass noise testing, just like the Laser dual cans for a R6 that Dallas got for his bike last week,

http://www.ebay.co.uk/itm/Yamaha-R6-...em3cbee e8d27

nothing in them as a lot of the silencing done on an R6 is in the exhaust collector system hidden away under the engine and out of site behind the fairing.

http://www.ebay.co.uk/itm/YAMAHA-YZF...em4cfb7 f97cf

He's going to get Austin Racing build him one, probably like the one he had on the RSV4 where you fit different inserts for diffent dB levels

A earlier R6 Silencer would be a better option
http://www.ebay.co.uk/itm/GP-Style-E...em23110 6a24c

[skidlids]

Originally Posted by bradders

how big do you reckon then? And what size diameter Kev?

I'd guess Craig's weren't an issue because he had 2?

50mm (2") core 16" long has been the norm for some time

Craig as you say has two cans that are linked so probably has nearer to 20 inches of silencing. Which is more than my bike has which when last checked at Oulton mine recorded 101.5dB. So its gone up by around 2dB over the season, soon be time to strip it down and repack it

Here are the MSV regs on Noise levels for their circuits
http://www.clubmsv.com/bike-testing-noise-limits.aspx

[bally71]

Don't know if you guys have seen this before

http://www.mez.co.uk/mezporting/exhaust_length.html

[bradders]

Originally Posted by bally71

Don't know if you guys have seen this before

http://www.mez.co.uk/mezporting/exhaust_length.html

ooo new website to baffle me! How does that work???

cheers Kev, I'll weigh up whether i'm better using what I have or selling them and getting another.

[skidlids]

Originally Posted by bally71

Don't know if you guys have seen this before

http://www.mez.co.uk/mezporting/exhaust_length.html

I was in their neck of the woods 2 weeks ago, they use to do my mate Marios (Maz) 906 Paso that he Drag Raced in the Supertwins class many years ago

[skidlids]

Originally Posted by bradders

cheers Kev, I'll weigh up whether i'm better using what I have or selling them and getting another.

My 620 Monsters got standard system so thats got to go, i've decided to go with a 2 into 1 similar to my 620SS

May see about getting one of my 2 into 1 conversions modified but in the short term I bought a S2R decat pipe earlier today for £29 and will see If I can use that. Already having one on my S2R out in the garage it LOOKS like its a possibility

[Jolley]

Originally Posted by bradders

but as he said many times it was down on power

the space where the pipes go up thru the shock is very limited and if you looked at his, it had one side much larger than the other. Take a lot of dyno work, messing around and cash to sort that right unless someone got lucky

the M620 doesnt have a hoop tho and I know you can fit a 916 shock so just wondered if there was more space, not got the bike home yet so cant just go have a look, but seems those that know think not

Paul, you could definitely do underseat, and it would work. It looks the nuts and saves a lot of work in an off (of which I had too many). My old B bike had 50-51bhp with the single side exhaust and went down to 48-49 with the underseat and rebuild. However, it isn't that straight forward. I have no direct comparison to the two exhausts with exactly the same motor. In addition, bhp isn't the whole story. Torque is the pulling power, and mine definitely pulled (at times) as well as Senna/Sorted/Ghost/Hugh's bikes, who were all amongst the strongest engines. With (only) 65bhp you should be able to get an underseat exhaust made up to expel the gases fast enough.

I don't see how it would be any harder than on my B bike... the front pipe came under the engine and through the swingarm, then connected with a short pipe from the rear cylinder before meeting the silencer. I don't see why that couldn't be done on a 620. The main technical "problem" with this set-up is that to keep a nice balanced motor the theory states that you should have equal length headers that provide the same flow/backpressure to each cylinder. Obviously this is impossible.