Are inducts needed?

[simon]

Dear All,
I've just taken bits off for the first time and seeing the inducts and after reading about the merits (and cost) of Lennies etc., I muse... What would it be like without the induct?
1). I would have thought this would allow more air in than the induct. There seems to be enough gaps about.
2). Wouldn't funnel muck/wet/bees onto the filter.
My reservations:
a) Is there a 'ram' or some other effect with the standard induct?
b) Be a bit noisier (oh well!)

Your thoughts welcome!

[Blackal]

Interesting!

I don't think there is much ram effect on the 1100s, but generally - engines benefit from some form of flow-management on the intake.

Take off the inlet pipe and give it a go - can't think you'll damage anything.

Al

[POB]

I'd like to know how you get on. I was thinking of the same (either removing the duct altogether or drilling the area around the bend). On several of my bikes I have used a jet kit / chip with a free-flowing air filter - in most cases "swiss cheesing" the airbox lid has made a big difference. I can't imagine the duct gets very pressurised, so what can you lose? Best would be to go to a dyno place and do a before and after... although I'm sure someone will claim some ram-air effect in a moment.

[das bike u1100s]

having fitted 2nd hand lennies to my 2004 bcr, i found i lost bout 25miles on the tankful. but that may be accounted for the fact the induct noise prompted to much use of the the right wrist to what i was used to!
I to would have said just drilling or taking of the oe intake would serve the same purpose, but then would idiots like me be sucked into spending mega bucks on lennies? proberly!
If this was the case, why fit K & N's etc why not just squirt fly killer near your air intake to reduce the need for a bit of sponge!
Ha! see i know nothing, but i felt the panzer performed better, so i was happy.
Good luck if you choose to try out your ideas, will watch with interest the results,

[madman]

Drill it full of holes. That would slow the airspeed down and keep the air at a higher pressure. I think that BMW must have known nothing about aerodynamics and deliberately designed something to sap engine power and ruin fuel consumption.

[r550s]

afaik lennie developed his induct because, to anyone, the OE item looks restrictive - you or I can theorise whether this is down to production/cost limitations, or noise restrictions, or both (but I don't seriously think that BMW 'ignorance' is part of the equation!). Lennie got on with the job and developed his idea using lots of dyno and real road testing (he ran his own R1100s), he only marketed the result when he knew that it was a GOOD THING for anyone else who was interested. As for cost - his advance cam sprockets, which were similarly developed and researched, are cheap as chips, I've got both and I think the induct is vfm. I'm only a layman, but I don't think induction tuning is simply a case of bigger is better, or drilling holes. I do think that extra induction roar is great-sounding, and is a good way to make a bike feel faster (it all counts!). It's also possible to junk airboxes/filters etc. and knack bottom-end power: then, when what's left of the intake system starts working above certain rpm, it can feel like a power boost. Have fun.

[POB]

Far be it from my place to advise BMW on intake / exhaust tuning! I'm not saying they didn't know what they were doing... but you have to admit that the OEM suppliers are playing to different rules than you and I.

Just as Lennie developed his induct, there is nothing to stop people experimenting. I'm sure someone on this forum ran without a duct for a while, but I can't remember who.

I can't comment on the riding of others, but my bike is a many-miles-in-all-weathers hard as nails commuter. I value low-down shove and sub-100mph performance *way* above racetrack numbers. I am also unoffended by airbox growlings from under the seat. What I don't like is leaves and most of a takeaway menu (turned into paper mache) inside my ducting. Ooh er.

I think if messing with the stock duct (holes or removal) improves low-down torque and legal-speed power delivery at the expense of 100-140mph performance, so be it. I'd rather be making very rapid and safe point-to-point progress than caning round a racetrack, but each to their own.

[r550s]

the 9' advance cam sprockets were about thirty quid delivered from oz - they can make a big (6 hp in my case) difference below 5,500 - the trade-off is supposedly about 1hp at the top end (big loss!). If your bike has a merciless life then there's a good chance that your cams might be running late anyway (there's exactly 14.7 kilometres of assorted chains needed to drive the cams, and BMW's manufacturing tolerances don't seem great anyway). If you think the bike might be a bit flat before 5,500 rpm, then you've the option of checking the cam timing.

[simon]

Well, I've been running for about a week (~5 runs). What's it like?..
Trouble was I changed a couple of things at the same time:
New air filter (std) .. the old one was v. manky
Induct off.
Cat off, y-piece on.
I slid an a4 sized bit of plastic sheet up between the tank and the central tank plastic (which goes above filter) shielding the air filter ... On looking at it, while the central tank plastic had guttering down the sides, there are a couple of slots through. The plastic sheet is to stop water from above.
So what's it like?
Well it sounds good! Crack the throttle open and feels like nadgers will be vacuum-removed.
It seems to go well enough, though with a week between riding with stuff on/off I find it hard to make a comparison. One thing that was noticeable was increase in tick-over of ~400rpm. Yet to check plugs. Only way to find out is to put induct back on.. but weather's too nice atmo!

Verdict: give it a go!

[Bender]

When I got mine it had a hole, about 2" x 3" cut in the duct jusdt ahead of the air filter (K&N)

When I took it into Bemer Bikes they asked me why I'd done it as it would have no effect on performance whatsoever.

I explained that it was there when i got it, and they advised me to patch it up.

Might get round to it one day...

[head-banger]

allllllllllrighty then!
a (very) brief explanation of why BMW/H#nda/Crapasaki et al have poor induction systems.
noise regs. any vehicle to get type approval has to be quiter than X dB.
induction suppression is needed to make sure the vehicle passes the noise test.
they are, and always have been a poor compromise, left to the punter to then sort out.
i have a couple of s/moto's with feck off holes in the airboxes to allow them to breathe properly (dyno set up), so allowing more air into the engine is a good thing, provided the the stoichametrically correct amount of fuel is added.
next week we will be discussing peace in palestine

[ianbcr]

now we know that thread would run for ever,that just aint never going to happen

[simon]

"..the stoichametrically correct amount.." ...the what? (maybe you meant "stoichiometrically" hem!... Not that I knew what that was either.. try http://www.thefreedictionary.com/Stoichiometrically)
wrt induction silencing, I have read somewhere that that was the function of the tubes... and concur, it sounds 'rorty'! Definitely passing my noise test!

[throttlemeister]

I have a Lennies, and I can't tell the difference, not in performance and not in sound. But then I always have earplugs in.