Bob,
There you go .... Mario is correct ... those da..m snowmobile people have metal velocity stacks; I have to look but I know I have seen them in about 3 different sizes and I am sure there are more, (I am not sure if we have 50 or 52mm OD necks though, (should write that stuff down ... because now I would have to go back out and measure). Clearly ... having the stacks in there make life much better ... When I was fooling with individual stage 7 type filters ... I was never really happy ... everything would be fine .. but every once in a while I would blip the throttle for a downshift or something and get a little cough .. I also never liked the difference between the front and the rear cylinders ... as the rears were always very sensitive to jetting changes and the fronts acted like they were doing you a favor to suck any gas at all out of the needle jet, (you could go two sizes over up front and they wouldn't care). It appeared to me that this was because of all the frame work in such close proximity to the rear filters .. that created an unequal airflow and unequal behavior. The only way I could really get equal behavior was to slide a UNI filter sock over each of the two front filters.
 
I fooled around with the 2" tail pipe for a while but never did it right .... I was trying to emulate the factory stack using the pipe and the mouth of the K&N filter ... Finally ... Patrick Ahearn did a stage 7 hybrid using an extremely aerated box .. .and I went back to the airbox myself ........ Then Steve got creative, (again), and simply shoved the factory stacks up inside of the regular stage 7 filters and it worked great ..... as he says .. several people have done this and it makes just enough difference without sacrificing the advantage of the individual filters, (it works great).
 
I still however ... like the box being there ... I have run, (just to see how it worked), for a test ride only and a couple of track passes with the stacks and box base but with a UNI foam filter sheet stretched across the top, (once even around the block with a large section cut out of a pair of women's panty hose), ... and it works wonderful. I though of having a plate cut, (have the outline right here on the desk), to screw to the top of the airbox but with the intention of mounting a flat automotive type filter on the top, (Patrick convinced me however that I probably had more surface area just staying with the K&N and the cut factory box top). I don't know if leaving the box base is really an advantage but I personally feel that it is ....... "because" ..  I feel that the area under the fake air cover is a high pressure area .. by leaving the sides of the box intact is forces all air to enter from the vicinity of the air cover, (plus I like to leave the bowl vent hoses up there so that they maintain an equal or greater pressure than the openings to the carb mouths.
That is my "twisted" theory though and many people have been trying to convince me that that area actually goes negative at high rpm, (I don't know .. they may be correct .. but I just feel that somehow I am better off without all 90 degree air flow going past the carb mouths).
 
If you wanted to just try stacks only .... you know you can pull the little rubber guys right out of the airbox base ........ you have the little holes in the side for the crank vent tube but you could plug those with some small PVC plugs and a little silicone fish tank sealer, (that is rated for 400 or 600 degree oily fish) .....
 
You may also want to look at Kinsler ......   http://www.kinsler.com/ ... they have spigot mounted velocity stacks ... or take a look at ... http://www.twminduction.com/ .. TWM has a wonderful assortment of throttle bodies and neat filter stock to go with them. The only problem with their stuff is that the velocity stacks are intended to bolt onto the top of their throttle body stock ..... sooooo .. you would have to machine an adapter to slide into the rubber spigots and bolt to the base of their stacks  ... This is a good thing however .. as you will note when you see the filter arrangements that go with these ...... There are several other places that have spun aluminum stacks to go on Mikunis ... I will have to search out a couple of those links and I will post them. I assume if you are going to run a bare stack that this would be for dyno runs or at the drag strip .........
campbell
 
----- Original Message -----
Sent: Monday, October 30, 2000 7:39 PM
Subject: Re: TC-Eric

steven detamore wrote:
         Bob,
             you're very welcome, glad you like my v-stack configuration. to
date everyone that has tried it has loved it.
             if you're not concerned about the filters, you can make up some
custom stacks from 2" exhaust piping and have them flaired at a pipe
shop.(credit TC for that one)
What about the Mikuni screened velocity stacks from the Snowmobiles??? They're polished aluminum too...

Mario
 

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