[YellowDuck]

Is that like from one addict to another?  Cause I know my bike is my drug of choice...

I'm in recovery, and doing quite well, thanks.  The key step for me was buying this particular bike *because* it is not very powerful, and knowing that for a few thousand more I could have bought something with twice the power, I have so far convinced myself that it would be silly to do anything in search of a few hp.  Same goes for weight reduction. 

The relative freedom from modification compulsion has been very liberating.  Updates so far have included brake pads (necessary and justified), bar end mirrors (totally unnecessary, the OEM mirrors are great), rear suspension (unnecessary, just fucking around for entertainment) and, soon, front suspension (also unnecessary, just messing about).

About the only thing I see left in the future is a very expensive but more comfortable seat, such as a Russell - the RE touring seat is not doing it for me.  Probably seat comfort is the #1 defect for me in the bike as designed.

This restraint is in stark contrast to what I got into with my previous two bikes.  I am proud of myself.

That is my story and I am sticking to it.

[ideola]

On Project MLG, I purchased an extra airbox from a salvaged bike on Fleabay.
I used a hacksaw blade to cut off about 4" of the factory runners (a little tricky but doable through the air filter opening).
I inserted an aluminum trumpet-style velocity stack (35mm x 52mm) into each runner (very tight interference fit, no need for clamp or any other retention)
I used a flap wheel bit on a dremel to port the throttle body interface on the exterior portion of the runner to match the larger bore of the Revelry Racing big bore throttle bodies.
I wrapped the entire airbox in self-adhesive Thermo-tec heat barrier.
I have not yet done any further testing of the CAI setup since the new build was completed.
The bike is currently at the Dyno shop, and I hope to get results any day now, and will be picking it up next Saturday.

[ideola]

I should add, one could very easily just cut off the runners the way I did and insert bellmouths without removing the airbox at all. The runners are accessible through the air filter opening, and while it is a bit fiddly to maneuver the saw blade in that opening, it's better than removing the airbox.

In my case, the bike was already apart for the big bore big valve cnc head big bore throttle body yada yada, so I took the opportunity to wrap the replacement/modified box since it was going to be swapped out anyway. The mechanic did bitch about how much fun it was to get it out and back in. But I think my modification approach could achieve similar results without having to remove the airbox.

[fireypete]

Sooo, cut the intake stacks 4 inches, buy some aluminum stacks, not that expensive and stick/stuff 'em on....thats it?  Jeez thats within the reals of my mechanical prowess...got big hands tho  that airbox is tight!
Perhaps buy a fuel x and use that to fix the mixture if it runs lean due to free flowing air filter and open pipes...Sounds like a plan...

[RecoilRob]

Sooo, cut the intake stacks 4 inches, buy some aluminum stacks, not that expensive and stick/stuff 'em on....thats it?  Jeez thats within the reals of my mechanical prowess...got big hands tho  that airbox is tight!
Perhaps buy a fuel x and use that to fix the mixture if it runs lean due to free flowing air filter and open pipes...Sounds like a plan...

I don't mean to get in the way of your plan...but it might be needing a little rethinking.  The intake stack diameter is fine for a 650, but really starting to get small fast on the Big Bore engines or one intended to make big power so you absolutely don't want to do anything to make the intakes smaller.   Someone was saying about sticking stacks into the cut off tubes...but that would decrease the diameter and while convenient is less than ideal.   A stack that fits over the tube reinforcing ribs while making a smooth and seamless transition to the stack interior would be the better way to go...but I'm not aware of any being offered at the moment.   Almost ready to pull the trigger on a 3D printer so I could make my own...but have been hesitating because I just don't need another obsession at the moment.

The addition of pipes mostly doesn't show much of an improvement and that's because of the stock ECU tuning can't take advantage of them.   I had to add quite a bit of fuel to make it run properly when going to the larger diameter pipes.   Then had to add even more fuel after putting in the S&S cam...which makes sense as it's pumping more air.

The change to 2" shorter stacks needed more tuning than even the cam did as they really change how much air the motor can inhale and where it's most effective.   Sorry but to really make the motor run properly you're going to need to be able to tune it with modified airbox stacks.   I'm liking the PowerTronic as it allows ignition timing changes and came in real handy with the shorter stacks to get it dialed in.   Went for a light throttle 'rideability' ride yesterday where top speed was only 65 mph and for a few miles with the rest in the 50'ish range and it got a little over 75 mpg's....not too shabby for a modified motor and has near perfect behavior.   It gets about 60 when ridden very aggressively and normally just hits 70 on my normal rides....so it's amazingly efficient and if this consideration is taken into account...the power production is pretty impressive for such an economical engine.

[ideola]

https://en.wikipedia.org/wiki/Venturi_effect

[RecoilRob]

https://en.wikipedia.org/wiki/Venturi_effect

I'm well aware of the works of Mr Venturi....how does that relate to the airbox?  I'm guessing you are saying that making the stacks narrower won't cause problems?  But of course it will!  Only a 'perfect venturi' can return all of the energy inputted while still allowing a section of reduced pressure to be used.  We don't have 'perfect venturi's' in the airbox and ANY reduction of area will hurt performance as well as having no need to create a low pressure feed...so why bother with venturi's?

[ideola]

We'll see 

[NVDucati]

I don't mean to get in the way of your plan...but it might be needing a little rethinking.  The intake stack diameter is fine for a 650, but really starting to get small fast on the Big Bore engines or one intended to make big power so you absolutely don't want to do anything to make the intakes smaller.   Someone was saying about sticking stacks into the cut off tubes...but that would decrease the diameter and while convenient is less than ideal.   A stack that fits over the tube reinforcing ribs while making a smooth and seamless transition to the stack interior would be the better way to go...but I'm not aware of any being offered at the moment.   Almost ready to pull the trigger on a 3D printer so I could make my own...but have been hesitating because I just don't need another obsession at the moment.
SNIP...

Yeah, 3D printing is very cool but a bit of a rabbit hole at the same time. The best path is to get your neighbor interested in 3D printing.
But an alternative to attaching the velocity bell to the tube is to use heat and press the shape into the tube itself. Think; brake line flange tool. The shape can be pretty quickly made by using the appropriate metal velocity stack as a mold buck. You can fill it with just about any epoxy based filler including common "liquid nail" construction adhesive. This will not be a long term production run. Don't forget the mold release and a well centered threaded "lolly pop" handle for using your new flange tool.

[Blazingatom]

For 3d printing search for bureaus, in the UK I can recommend 3DPRINTUK in the US shapeways, both are very well priced an for intake stacks probably cost I  the region of £20 to £30

[fireypete]

My bike is the stock 650.  It seems a simple way to get the bike to run a bit better.  I just don't have the knowledge of air flow to really nut it out more than "cut 'em off, stick bell mouths on 'em"  and looking at what I just wrote...perhaps I should stay out of the shed! The fuel x is mentioned on a tec bike youtube vid. Seems like a reasonable idea.
I must also consider, whilst I would like a bit more power the bike is running nicely, a little breathless up top is about it.  And I could manage to duck that up ;

[fireypete]

Hi Rob,
Your engine is quite modified isn't it?  So it would really benefit from more air.  But a stock 650...

[RecoilRob]

Hi Rob,
Your engine is quite modified isn't it?  So it would really benefit from more air.  But a stock 650...

Well...the engine has never had the head off...but does have S&S cam and TEC pipes so we'd call the modification 'minor'.

I AM curious as to what shorter snorkel tubes would do to a totally stock bike?   There is a large chance that doing that would throw the ECU into a tizzy and aftermarket fueling might be needed to retain good ride-ability....but it's too late to experiment on my bike.

[John Mullen]

My Interceptor has pistons and cam and has wicked low-end torque.  It's a torque monster.  So I guess I wouldn't think of modifying the airbox.  It's too sweet the way it is.  I couldn't dream of any better throttle response.  My tuner sure did a great job of dialing in the Power Commander for my bike. Now I have to just leave it and enjoy it.    If it ain't broke........

[ideola]

My tuner sure did a great job of dialing in the Power Commander

None of these mods make much sense if you aren't going to take it to a tuner to be dialed in. The maps provided by Revelry, Hitchcocks, and S&S will all get the bike running decently, but there are so many variables from one build to the next, there's no way any of those maps will be optimized.

The tuning shop I am using is only charging me $250 to build an optimized map, which is a drop in the bucket compared to what I've put into both builds (Project MLG and The Rocketeer). Well worth the cost, IMO. He asked if I wanted to do pulls on the current map and I told him don't bother.