I've shortened my air intakes, so here's some pics...

mrTickle

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Loosen the 3 clamp screws on each side of the throttle bodies.

When you've done that, push the plastic air intake tubes into the air box and remove the metal throttle bodies from their mounts.

This will now enable complete removal of the plastic air intake tubes and should look like this.
 

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Modified air intake ( I trimmed about 3" off )
 

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Picture showing the uncut tube and the modified cut tube
 

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_______________________________________________
Originally quoted by Geezer

"Bah Humbug"

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Geezer, You were my inspiration for this mod. Top man but do try to keep up on our next ride home from Doggetts... :moped: :D
 
Yeh ! Sorry about that, I'm not used to going the wrong way down one way streets & riding along the pavement. I'll have to get some practice in !!!!!:D :D :D :D :D :D :D :D :D
PS Glad the mods to your likeing!
 
Wouldn't it be better to retain the bellmouth and to shorten it in the middle? Presumably the bellmouth is there for a reason?
 
Hey Mr Tickle

Lose 3 stone and the result is even more low down power for free!

:beer: Carbohydrate_unsatr8 knows how not 2 :beerjug:
 
Strange, that......shortening the intakes INCREASES the resonant frequency, usually shifting the power higher up the rev range. (Think of pipe-organ tubes).
 
Don't understand the technicalities of this mod, but it worked for me.

I saw the teeny bellmouths (more like smoothly rounded edges really) on the air intakes, but figured that they're so small, they'd be more or less ineffective.

The air intake tubes are only cheap bits of plastic that can easily be replaced ( if you don't like the end result of more power :) ). The mod seemed to work for me and there are at least 2 others on the site that've done it and obtained similar results. We've all got Techlusions' fitted though, so whether that makes a difference or not, I don't know.

Anyone else done this mod?

P.S:- Carbo, I reckon if I lost 3 more stones, I'll out accelerate GSXRs' (well the wrong way through Greenwich anyway...:D )
 
Longer pipes

Little Red Rooster (obviously a Stones fan?) true you will get more torque with a longer inlet, however the inlet comes after the throttle plate.

Race bikes have the carb or throttle body as close to the cylinder head/inlet as possible with as big an opening as is permitted. This means that the engine may have sod all torque and power below for example 3/4000 rpm or even much higher, but at the top end of the rev range alot more available power.

To produce a slogging engine i.e. for trials riding then the inlet tract is longer.

If Mr. Tickle were to put the throttle bodies as far back as the reinforcing area of the air hose then he would notice a tremendous difference, the torque would be alot lower down but the top end power would tail off perhaps too early for normal road riding.

In effect cutting off a piece of the air hose is no different to making extra air holes in the air box of any bike it will simply allow more air in to be used by the engine (that it can draw in), we used to cut 2 inch holes into the sides of 250 and 350 Yamaha LC's up the jetting and then watch them fly. BMW and any other manufacturer design the air box and subsequent hose work to produce a compromise between good power characteristics and torque curves for the purpose the bike was intended. No doubt with some cutting and drilling here and there differences will be noticed.

The flutes (curved edges) are there to prevent the air being drawn in from literally bouncing off the now flat edge. Add a trumpet to a straight cut inlet and power increase, not dramatically but by at least 2-3%.

So Mr. Tickle if you measure the inside of the piece cut off at the fluted end you may find it to be narrower than the new entrance now created. If you can I would try to gently radius the edges of the cut tubing or modify your air pipes so that the original flutes can be incorporated.

Probably the main reason that someone has done this is to give a slight increase in induction noise which is in it self mind over matter as 'more noise mut equal more power'.

Be interested to see a Dyno print out.

Overall Mr BMW has now had his harmonics altered.
 
Longer pipes

Little Red Rooster (obviously a Stones fan?) true you will get more torque with a longer inlet, however the inlet comes after the throttle plate.

Race bikes have the carb or throttle body as close to the cylinder head/inlet as possible with as big an opening as is permitted. This means that the engine may have sod all torque and power below for example 3/4000 rpm or even much higher, but at the top end of the rev range alot more available power.

To produce a slogging engine i.e. for trials riding then the inlet tract is longer.

If Mr. Tickle were to put the throttle bodies as far back as the reinforcing area of the air hose then he would notice a tremendous difference, the torque would be alot lower down but the top end power would tail off perhaps too early for normal road riding.

In effect cutting off a piece of the air hose is no different to making extra air holes in the air box of any bike it will simply allow more air in to be used by the engine (that it can draw in), we used to cut 2 inch holes into the sides of 250 and 350 Yamaha LC's up the jetting and then watch them fly. BMW and any other manufacturer design the air box and subsequent hose work to produce a compromise between good power characteristics and torque curves for the purpose the bike was intended. No doubt with some cutting and drilling here and there differences will be noticed.

The flutes (curved edges) are there to prevent the air being drawn in from literally bouncing off the now flat edge. Add a trumpet to a straight cut inlet and power increase, not dramatically but by at least 2-3%.

So Mr. Tickle if you measure the inside of the piece cut off at the fluted end you may find it to be narrower than the new entrance now created. If you can I would try to gently radius the edges of the cut tubing or modify your air pipes so that the original flutes can be incorporated.

Probably the main reason that someone has done this is to give a slight increase in induction noise which is in it self mind over matter as 'more noise must equal more power'.

Be interested to see a Dyno print out.

Overall Mr BMW has now had his harmonics altered.
 
Humble Bumble Bee.

Its nothing to do with aerodynamics more a case of no one actually telling the dear old Bumble Bee that it can't fly, therefore it does. As nobody has developed Bumble Bee speak I doubt the Bee will ever know the real truth and just go on its own inimitable way.

More to the point, how the hell do those holiday return flights ever get off the ground when no bugger weighs the luggage, we watched one guys case go through and it showed 45 kilos on the scales. The next came up as 38 kilos, geez... and it was for the same plane I was going to travel on.

This must explain all those immaculate take-offs and landings going out (everything weighed) and then why on the return the dam plane almost goes straight through the runway on touch down!

Bbbzzzzz.......bzzzz...bzzzzz....goes the GS rider, bzzz...bzzz...bzz
 
I got hold of a set of cut down tubes and have given them a try, they are cut down to where"Mr Tickle's" thumb is in the second picture of the original posts and the cut ends have been smoothed to make bell mouths.
My bike has a Y-piece and Remus end can and has suffered from vibs and back fires since they were fitted but power,torque and fuel consumption have all improved.
I put the new tubes in yesterday took about 20 minutes. The bike felt more responsive on the quick try I had yesterday but coming to work this morning 40 miles M61 M60 A34 the bike had smoothed out the vibs have gone or at least it is smooth as the standard set up and no backfire!
I don't pretend to understand how this works but it seems to (the backfire did startle a few car drivers whilst filtering though I'll miss that).


Roger
 


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