A freind of mine who happens to be a former honda service dept. employee, suggested that if I put on a slip on exhaust that took the flapper out, that I would lose mid-range power but gains at the top of the rev range. I'm not too sure I buy that thoery since the "flapper" is non-existent in the racing arena. Your thoughts on this? Anyone have any real life dyno comparisons to bust this myth?
Another butterfly flap thoery...
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Sounds about right, doesn't the flapper do the same job as the EXUP on the Yamaha? I was gutted when I fitted a full system to my '00 R1, it did make more grunt in the higher rev range but made low speed riding through traffic a nightmare. It wouldn't carburate properly if you gave it a fistful until it got above certain revs.
I assume the fuel injected bikes can handle the loss of the butterfly better, although if I do buy a blade I think I'd rather leave it in place and get a slip-on can instead.
(I sold my R1 last week and am looking at the 1000rr to replace it, getting a bit put off with all this talk of knocking noises). Hope the gearbox is tighter than my R1 was, that sucked big time!
I assume the fuel injected bikes can handle the loss of the butterfly better, although if I do buy a blade I think I'd rather leave it in place and get a slip-on can instead.
(I sold my R1 last week and am looking at the 1000rr to replace it, getting a bit put off with all this talk of knocking noises). Hope the gearbox is tighter than my R1 was, that sucked big time!
The thing that makes me wonder is that when these manufacturers come out with comparison charts on dynos from stock and aftermarker pipes, it shows no dip (at least compared to stock) on the power curve. Are these legit? or is a full exhaust system the only answer to retain the linear power curve that our 1000rr have?
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1,394 Posts
The theory is the added back pressure will incease exhaust velocity at low RPM's for better scavenging of the cyliders at lower RPM's. Since the headers are designed large for maximum HP from the stock engine, that is how they get over the compromise.
Me personally, I plan to leave it all stock. It makes more power then I need on the street, sounds great without being excessively loud (don't want to attract attention to my daily driver), and looks better then any aftermarket exhaust I have seen for it.
EFI shouldn't make a difference with the valve removed. The carburation problems come from the pressure pulses that are inherent in the design of the engine. At some RPM's they are flowing the right way for a better air charge (why it is possible to get over 100% VE), at other RPM's that will cause the intake air to pass through the carb 3 times (intake, reverb out, then intake again) causing a very rich mixture. That is what the EFI prevents. The valve in the exhaust will not effect the pressure waves.
Those pressure waves are why exhaust lengths are so important.
Me personally, I plan to leave it all stock. It makes more power then I need on the street, sounds great without being excessively loud (don't want to attract attention to my daily driver), and looks better then any aftermarket exhaust I have seen for it.
EFI shouldn't make a difference with the valve removed. The carburation problems come from the pressure pulses that are inherent in the design of the engine. At some RPM's they are flowing the right way for a better air charge (why it is possible to get over 100% VE), at other RPM's that will cause the intake air to pass through the carb 3 times (intake, reverb out, then intake again) causing a very rich mixture. That is what the EFI prevents. The valve in the exhaust will not effect the pressure waves.
Those pressure waves are why exhaust lengths are so important.
Joined
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1,394 Posts
The theory is the added back pressure will incease exhaust velocity at low RPM's for better scavenging of the cyliders at lower RPM's. Since the headers are designed large for maximum HP from the stock engine, that is how they get over the compromise.
Me personally, I plan to leave it all stock. It makes more power then I need on the street, sounds great without being excessively loud (don't want to attract attention to my daily driver), and looks better then any aftermarket exhaust I have seen for it.
EFI shouldn't make a difference with the valve removed. The carburation problems come from the pressure pulses that are inherent in the design of the engine. At some RPM's they are flowing the right way for a better air charge (why it is possible to get over 100% VE), at other RPM's that will cause the intake air to pass through the carb 3 times (intake, reverb out, then intake again) causing a very rich mixture. That is what the EFI prevents. The valve in the exhaust will not effect the pressure waves.
Those pressure waves are why exhaust lengths are so important.
Me personally, I plan to leave it all stock. It makes more power then I need on the street, sounds great without being excessively loud (don't want to attract attention to my daily driver), and looks better then any aftermarket exhaust I have seen for it.
EFI shouldn't make a difference with the valve removed. The carburation problems come from the pressure pulses that are inherent in the design of the engine. At some RPM's they are flowing the right way for a better air charge (why it is possible to get over 100% VE), at other RPM's that will cause the intake air to pass through the carb 3 times (intake, reverb out, then intake again) causing a very rich mixture. That is what the EFI prevents. The valve in the exhaust will not effect the pressure waves.
Those pressure waves are why exhaust lengths are so important.
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8,382 Posts
This bike is great, but far from awesome right out of the box... Power is good & it stays where you put it in the corners, but it overall handles like a turd with some rather heavy steering. I'm going to play around with the geometry this weekend after I install the Ohlins shock & if that doesn't make it at least 50% better I am going to yank that HESD damper off & see what happens then.
Hijack Heavy Steering
Hijacking the thread a bit.
It does steer heavy. I am getting used to it (1500 track miles now), but it does steer heavy. I rode a 636 Kawa a couple laps and then got back on the RR.... First corner I looked down to see if I had a flat tire!!!!!!!!
That was when I noticed how slow it steers. Max at Traxxion says the damper should go. I lengthened the Penske about a quarter inch and will see how that goes. I do notice the damper negatively in slow corners at high rpm on the gas exiting. It steers like a pig then. I use a lot of track.
Ernie
Hijacking the thread a bit.
It does steer heavy. I am getting used to it (1500 track miles now), but it does steer heavy. I rode a 636 Kawa a couple laps and then got back on the RR.... First corner I looked down to see if I had a flat tire!!!!!!!!
That was when I noticed how slow it steers. Max at Traxxion says the damper should go. I lengthened the Penske about a quarter inch and will see how that goes. I do notice the damper negatively in slow corners at high rpm on the gas exiting. It steers like a pig then. I use a lot of track.
Ernie
How much of that do you think is attributed to the huge amount of trail though? According to Honda's website, the 1000RR's got 102mm! The G1K I was riding the other day had 96mm, about the amount most racers I know run. Switching between the two bikes, there was a massive difference in required force for turn-in.
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