Exhaust restriction
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LotusSevenMan
- Posts: 1915
- Joined: Wed Sep 06, 2006 8:32 pm
- Location: Liss, Hampshire. UK
Well I did the mod today so here is my two penth for what its worth....
1) Smoother reving
Have to agree with the OZ dudes as the bike is noticeably 'smoother' from idle 1200rpm to 4000rpm. I can't really say if its 'smoother' above 4000rpm as it was always pretty smooth reving from that point to the red line anyways.
2) Less raspy exhaust note (suits my preference)
At idle both Scorpion race cans are pumping out an equal amount of gas with the 'two hand test'. Before the mod I could only ride for 2/3mins with out earplugs (as soon as the pipes were at full operating temp they would get much noiser than from cold) today I road for a full hour with no complaints. Granted the "thump" isn't as strong as before as two cans are absorbing the noise where as before it was 80% RHS and 20% LHS (my guess) Defo better in my opinion.
3) Reduced engine braking
I don't really miss this but the bike has lost a little "character" it still has better engine braking than a CBR600 but i'd say its 1/2 as strong as it used to be.
4) Less backfiring on overun
I'd guess this follows from 3) defo suits my preference as this used too wind me up.
5) Less torque in 4000-5000 ish range
I have a 15t sproket, in 2nd gear at 4000rpm if I give her full throttle to the red line it is definately less agressive. It reminds me of a VFR800 or CBR600 you get a change of engine note when you give it full gas and the pickup comes later. Previously there was no delay, not a sniff
Some dyno time may get back some of the lost torque . I feel pretty sure the restriction was there to boost torque. There are guys in this forum who have gone from two exhausts to one and all state that "torque goes up but you loose top end". Seems to me that with my 80% - 20% anology Honda were balancing the exhaust so that a large porportion is just going through the RH pipe i.e just one exhaust for torque.
All in all I'm happier with the bike now than I was before, it sounds better is easier around town as the engine braking is less severe and I can enjoy the sound with out earplugs!. If you don't mind loosing some power and engine braking then the mod is a no brainer.
1) Smoother reving
Have to agree with the OZ dudes as the bike is noticeably 'smoother' from idle 1200rpm to 4000rpm. I can't really say if its 'smoother' above 4000rpm as it was always pretty smooth reving from that point to the red line anyways.
2) Less raspy exhaust note (suits my preference)
At idle both Scorpion race cans are pumping out an equal amount of gas with the 'two hand test'. Before the mod I could only ride for 2/3mins with out earplugs (as soon as the pipes were at full operating temp they would get much noiser than from cold) today I road for a full hour with no complaints. Granted the "thump" isn't as strong as before as two cans are absorbing the noise where as before it was 80% RHS and 20% LHS (my guess) Defo better in my opinion.
3) Reduced engine braking
I don't really miss this but the bike has lost a little "character" it still has better engine braking than a CBR600 but i'd say its 1/2 as strong as it used to be.
4) Less backfiring on overun
I'd guess this follows from 3) defo suits my preference as this used too wind me up.
5) Less torque in 4000-5000 ish range
I have a 15t sproket, in 2nd gear at 4000rpm if I give her full throttle to the red line it is definately less agressive. It reminds me of a VFR800 or CBR600 you get a change of engine note when you give it full gas and the pickup comes later. Previously there was no delay, not a sniff
Some dyno time may get back some of the lost torque . I feel pretty sure the restriction was there to boost torque. There are guys in this forum who have gone from two exhausts to one and all state that "torque goes up but you loose top end". Seems to me that with my 80% - 20% anology Honda were balancing the exhaust so that a large porportion is just going through the RH pipe i.e just one exhaust for torque.
All in all I'm happier with the bike now than I was before, it sounds better is easier around town as the engine braking is less severe and I can enjoy the sound with out earplugs!. If you don't mind loosing some power and engine braking then the mod is a no brainer.