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roger 04 rt
New member
You will find those who say it makes a difference but if it does it's small. May reduce top end power. There is also one unconvincing dyno run that's been around for 15 years. Out of the 256 fuel cells in the fuel table, the run tested about 9 of them.
Is it a bike you're thinking of buying?
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cele0001
Instigator
I would consider it a no cost option, if we is trying to "sell" it you.
pauls1150
MOA #24991, south of Los Angeles
I did this on my '97 R1100RT, and yes it made a difference, and yes it is a small difference.
I have not bothered trying it with my 1150's.
This "trick" has been used for many years (even before Oilheads were available) as another way of tuning the intake side of a fuel-injected system (a neighbor with a drag-racing boat was quite familiar with this before I did my '97); the idea is that longer intake tubes move the torque curve lower in the RPM range (similar to exhaust pipes). A tiny bit of top-end is lost, but unless you race, it is not noticeable (the additional lower-end torque boost may even help off the line...). The main benefit was/is supposed to be a stronger midrange.
A couple of the shops in this area tried this (at customers' request) and results were mixed. Some bikes responded well, others immediately started spitting and backfiring, and the question remains as to whether changing the CCP (Catalytic Converter Coding Plug) needs to be changed to accommodate this. I'm aware of at least one 1100GS - which of course came stock with the longer tubes - that was not running "typically" and changing its tubes to the RT/RS version fixed it! However, the actual "Root Cause" of this case was not resolved.
The how-to is on the Internet BMW Riders oilhead tech site. The HP/torque chart here is from that site.
I have not bothered trying it with my 1150's.
This "trick" has been used for many years (even before Oilheads were available) as another way of tuning the intake side of a fuel-injected system (a neighbor with a drag-racing boat was quite familiar with this before I did my '97); the idea is that longer intake tubes move the torque curve lower in the RPM range (similar to exhaust pipes). A tiny bit of top-end is lost, but unless you race, it is not noticeable (the additional lower-end torque boost may even help off the line...). The main benefit was/is supposed to be a stronger midrange.
A couple of the shops in this area tried this (at customers' request) and results were mixed. Some bikes responded well, others immediately started spitting and backfiring, and the question remains as to whether changing the CCP (Catalytic Converter Coding Plug) needs to be changed to accommodate this. I'm aware of at least one 1100GS - which of course came stock with the longer tubes - that was not running "typically" and changing its tubes to the RT/RS version fixed it! However, the actual "Root Cause" of this case was not resolved.
The how-to is on the Internet BMW Riders oilhead tech site. The HP/torque chart here is from that site.
roger 04 rt
New member
Reports from the riders who added either an Innovate Motorsports LC-1 or a Nightrider AF-XIED have been that with or without the Intake Tune change (mike at Beemer boneyard already had the tubes on his r1100r), the LC-1 or AFXIED gave a big mid-range boost, smoother mid-high range and no top end loss.
RB
RB
happy wanderer
Day Dreaming ...
I had installed a set of long GS intake tubes on my 1100RT and other than a bit more "honk" sound when I opened the throttle all the way I could not feel any difference. I am one of the testers of the AF-XIED Roger mentioned and I subsequently installed an LC-1 wideband O2 sensor kit on my 1100RT. After running quite a few tests and gathering data Roger suggested I try removing the longer tubes and test again. If there was any difference I really could not notice it and the bike ran every bit as well as before removing them.
That dyno image may show a tiny bit of improvement but my butt dyno could not measure it. I don't think the GS tubes hurt anything but in the end not worth the trouble or expense in my case. I tend to think the designers knew what they were doing and left it back in stock configuration. The LC-1 (AF-XIED's grandpappy) on the other hand did more to improve performance on my bike (including better mileage) than any other thing I have tried. And I've tried pretty hard...
That dyno image may show a tiny bit of improvement but my butt dyno could not measure it. I don't think the GS tubes hurt anything but in the end not worth the trouble or expense in my case. I tend to think the designers knew what they were doing and left it back in stock configuration. The LC-1 (AF-XIED's grandpappy) on the other hand did more to improve performance on my bike (including better mileage) than any other thing I have tried. And I've tried pretty hard...
