Hey Guys,

I have a great Modification for the Tube, it is FREE, well sort of. Take the internal spring from an old foam UNI filter. If you do not have one buy a UNI filter, one that is 6" long with a 2"ID approx. $10.00 or so, most shops have old filters that they will give the spring away. Take the spring and do a little pulling and stretching to match the internal contour of the tube. Be sure to stretch the spring the entire length of the tube ensuring that it is evenly spaced. Wrap the last wind under it self on the filter side of the tube to prevent it from backing OFF into the filter. This only takes a few minutes and some care when you put the tube back into the box. If you do it right the tube will be as hard as a donkey D*%#. It made a difference, and no one has to pay anyone a cent for THIS MOD.



Later

 

Everyone seems to be focused on the fact the tube will collapse under hard acceleration. This is not the only problem. Even if you make the stock unit stop collapsing, then you have IMPROVED but not SOLVED the overall problem of not enough air flow. A replacement design which gives you more air flow, similar in performance to a filter directly on the card is what is needed. I recall the filter directly on the card yields 3 HP more than stock. So assuming you stop the stock tube from collapsing, you've gained maybe 1/2 HP because the engine still needs more air than the stock tube can provide even in 'perfected' form. Lets all remember, that the stock exhaust is very restrictive, so when coupled with the stock air tube, there is no air flow problem from the factory. By adding an aftermarket exhaust or other performance items, we create the need for better than stock air flow into the carb, so that we can fully take advantage of the increased air flow out of the engine - hence an aftermarket air intake system.

 

BlackHawk, Yeah that's what I was intending with my original post/question of this thread. When you add aftermarket mods like cdi,pipe,jetting,etc.,like on my machine for instance, it makes the problem even worse. I would like to see improved flow as well as stopping the collapsing of the tube. I totally agree with your observation Chris. I'm sure everyone has had some ideas/thoughts on how to stop the "incredible shrinking tube" and some are very good ideas. I am looking for a replacement solution that hopefully isn't too expensive.

 

I'm not laughing at this thread at all. I'm reading some very intelligent coments and thoughts.

The tube is both too soft and too small. Stopping the colapsing will help, but not solve the problem. I'm currently working on a replacement tube, but am relatively in the developement and don't have any #'s to share yet. I want to ensure that it can work with the stock carb as well as the Mikuni's that many of you have. This is slighly more difficult since it is a stiffer material.

Maybe I should not have shared that tip, since it seems that another manufacturer is working on it as well. If someone want to share who it is working on the tube, I can compair the two, so I offer whichever one works best.

 

I can see the more modified,and bigger bore machines like the one's you biuld needing a bigger more free flowing tube. But surely the size of the stock tube would be adequate for a stock machine with a couple of bolt-ons. I don't mean to step on your toe's,because I know you know a hell of alot more than I do about this motor and its potential. I think if you do biuld a after-market part to replace the tube, It most likely will be the best one out their. Like it or not you are the bombardier/rotax650 GURU on this forum, becuase you offer your expertise on subjects like this one. I for one, and I think I speak for everyone, Appreciate the advise. Agian,I think when your part is done it WILL be the best one you can buy. bar none.


P.S. I apologize for speaking for you.

 

Actually, all of the testing I have done for this tube, has been on a stock machine or one with just a few bolt ons. The tube is too small for even these motors. The loss I had on the 760[by using the tube] was too dramatic to chart. I completely understand that not everyone has a big bore, and do ALOT of research for stock of near stock motors as well.

Keep in mind folks, I want to service all DS riders. Racers as well as recreational riders. 120HP monsters down to stockers. Desert, Sand, Trail, Woods, MX, TT, Water[I talked to a customer this morning that likes to skip his DS across water] or any other type of riding.

The representative of another DS performance shop has posted "No Playbikes", and maybe they don't wish to service anyone but all out racers, but I can assure you that we try to develope as much for the recreational rider as we do for the racer.

 

I like the carb mount filter but my seat is crushing it I think. Has anyone cut their seat to make the filter fit better? Any pictures?

 

The spring inside the tube idea is a good one but makes the air tumble and turbulent and cost horsepower. The incoming air needs to be smooth for good flow.
Bearman

 

Marky,

Assuming your product did work well for stockers, it seems to me building a similarly priced part that will work as well for stockers AND modified machines would be best. Everyone 'dreams' of the day they'll win the lottery, and have half a dozen DSs and other ATVs in their garage all with extreme mod kits. I like the idea of buying a part that will help my performance now in a relatively stock form, but wont have to be trash-canned if I ever go bigger. If I buy something aftermarket, I would like the most compatibility with my basic pipe all the way up to the high performance kit I'd love to get. Why not try and design a product that will work for a more highly modified machine as well as stock? Sure it takes more work, but it also appeals to a larger market.

 

As my Boiler Combustion Expert put it. . . air in = air out.
If the pipe/muffler is restrictive, a high flow carb / air filter will do little by itself. If the air filter / carb are restrictive an aftermarket / less restrictive pipe will do little by itself.

Knutz: Does the Quicksilver carb offer better combustion air flow (I have been thinking about this carb upgrade)? Is this why you offer the different carb in your packages (to increase air flow)? Is it just air flow or also fuel flow?

How much power difference is there between: K&N, Jetting & Pipe vs. K&N, Jetting, Pipe and Carb?

I hope I get a refund on my taxes this year.

-Mark

P.S. Also, are you hearing anything on factory fuel injection from Bombardier? I love my DS but, might have to buy a new one if this was an option.