I need a ported dirtbike velocity stack ASAP!

[thedeatons]

Anyone have one? I can either buy it, or preferably just borrow it for a few weeks while I work my intake setup out.... Thanks!!!!

[Canniboomer]

My clamp-on filters have a huge surface area compared to stock, so I don't understand your previous claim that an inlet bend filter would be too small?... Anyway, the direct intake for the dirtbikes is well underway and refined for almost a year now, but I stocked out of the first batch of 6 pretty quickly. About 10 more are getting worked up this weekend, since a few guys are still waiting.

But if you are still intending to use a full-frontal and weather exposed 90-filter, I have the ATV inlet funnel with 2-3/4" flange, and that also uses an epoxy-backed shorthorn funnel. The epoxy makes it rigid for easier boring, but you can only take the top half out to about 46mm. From halfway down, you could taper-bore that to open wider and transition to the throttle body where it meets -- or straight bore it and live with 45 to 46mm max.
But I'm not interested in doing that, since these front ends are jumping up already on the dirtbikes!

But if 2-3/4" would work for your filter flange, my adapted ATV shorthorn would be a solid start..... $45.
Pictured here is the Dirtbike E-frame unit, FYI. (vacuum feature is direct to the throttle body now, with a drilltap included).

[thedeatons]

I love your unit (I bet you don't hear that everyday!)...

My issue is that I am going into a Timbo ported head, and I want minimal restriction. I don't want a standard velocity stack that acts as a restrictor plate, in which case I may as well not have ported the head. Know what I mean?

At this point I am seriously considering getting a piece of 3.5" ID silicone hose (90 degree bend) and mating that to the Cyclone on the throttle body, then running my 250R No-Toil off of that, between the frame spars.

Boomer if you had your setup mated to a ported Cyclone I would be all for it..... (hint-hint).

By the way, I don't remember mentioning an inlet bend filter being small, did I?

[wistech]

I may have an opened up bike stack back at the shop. It may be ruined as machining them to 46mm is darn near impossible and the lathe may have gone through it. I will check .

[Canniboomer]

QUOTE (thedeatons @ Jul 27 2008, 07:23 AM) <{POST_SNAPBACK}>

At this point I am seriously considering getting a piece of 3.5" ID silicone hose (90 degree bend) and mating that to the Cyclone on the throttle body, then running my 250R No-Toil off of that, between the frame spars.

I think you will find that the elevated inlet of a 3.5" elbow will sit too high, and start too far rearward. A straight 250r filter might
fit between the frame spars OK, but your fueltank will contact it long before the tank meets the frame. My cone K&N is not quite as large as the 250r filter, and just barely clears the tank -- and of course it starts to taper from a point that is lower and more forward.

I wouldn't worry about having the Timbo-ported head, as you will still see plenty of improvement. But having the upper section of the throttle body also ported for a wide-ATV Cyclone transition is sort of like getting the cart before the horse. You can clamp a Cyclone in there no problem, but actually using it to an advantage, and feeding it with a wider filter or flange will be tough, and the larger the elbow?....the smaller the filter. Space is very limited, so you have to make some choices. A custom filter might work, but it will have to bend down toward the motor more sharply with a tighter taper. A straight flangeless sock filter might work, and you could clamp it on crooked to a sharper downward angle to clear the tank -- that might work.

....but here's a pic of a 3-3/4" wide filter off of a lower inlet than you intend -- I think you can see what I mean from this pic. The K&N is even larger and tapered, and not pictured. And the newer foam version will be 1-inch longer, and almost twice the free surface area compared to stock. BOTH filters have an inlet bend offset -- straight filters did NOT fit.

Or maybe some custom clamp-on wedgie thingie would work?
......Wedgies anyone?

[wistech]

I think some dyno testing is required before wasting anymore time arguing about filters and elbows. It hasnt even been proven that the stock box is any hinderence at all. Just guessing going on here. Come up with sojme systems and lets put them to the test.

[Canniboomer]

...some guys will like ditching the brittle, and pricey stock airbox.
...some guys will like the ease of dropping the motor in and out.
...some guys will like not having to come up with a clamp-bolt mod the get to the sparkplug clamp.
...some guys will like removing a filter that is uniformly used, and not plugged up on top with bright and clean sides.
...some guys will prefer a clamp-on filter, and not a greased base.
...some guys will prefer to use an Outerwear, or to self-shed debris better even without one -- rather than picking fir needles and grit out of the edges of your filter that get pushed into it by shimmy contact with the tank.
...some guys will want no chance of wicking the moisture that will sheet onto the fueltank surfaces while riding in the rain.
...a flimsy funnel is not very bore-able as you say, even to 45 or 46mm with any integrity left.
...plenty before you have asked for this exact thing,.... so it has evolved by customer-request and for a variety of reasons.

I don't know what the dyno result will end up by comparison, but feedback and indicates more power. And I will sell more than I can hope to make anyway, and for a whole slew of valid reasons.
I have not messed with Dyno-ing these, since I'm too busy and oversold already without even mentioning them on the forums, and several already KNOW they work just fine, and will require some tweaking to increase the fuel flow (if the tank plumbing is not also fixed at the same time)... One guy, Mike-from-Ohio, is somewhere in your area and gave feedback -- he's very pleased, and he WON'T be going back to the former setup... One other guy Tearoam was expected to have one Dyno'd by now also, but we have not heard back from him yet. He never mentioned that he was having his throttle body fully reamed, so I'm not sure of the results to expect -- but the large K&N will deliver plenty of air.
Anyway, I'll just leave it to YOU guys to get together and visit the Dynos, and then come back with opinions.

[thedeatons]

LOL.... Good post Boomer. Honestly if my engine were a stock 432 I wouldn't even care. Since I thrwe $400 worth of porting at it I would like to see all of that money making it's way to the ground via my rear tire...

The bike will be dyno'd, but only because I want to make sure the map is right before hitting the higway. I do NOT want to sit at the dyno for four hours testing 5 different setups though. If I can see the 49hp I expect out of it to match my friend Janell's quad, then I will be happy. I will be dynoing the bike with a quad rear end on it, so power "should" be identical, as every part inside is the same.

I have a Cyclone I am bumming for the moment, and I already have a 250R filter that does fit between the spars after some coaxing. What I may do is remove the rubber velocity stack mounting portion of the Cyclone and fit a steel sleeve, the use a 2" 90 degree silicone hose and band clamps to go from the Cyclone to the throttle body. From the measurements I took it looks like it will work alright. Perhaps knife-edging the top of the throttle body will take the step out of the intake too if I use that silicone 90.

Eventually maybe John will get around to figuring out the best setup for hp, for now I just want a simple setup with not much restriction to my ported head... ya know?

[cannondale27]

Johns theory is that even with stock airbox removed you are still sucking air from between spars and tank.Not much more area than the xr50 sized stock box and now you are also getting any heat coming off the rails,motor and radiator.He isnt sure of anything because it hasnt been dynoed but think about it.Makes sense.

Personally I have never seen a intact airbox.Either style.I just mystifies me why Cannondale made such a nice quad box and such absolute junk for the bikes.Think of how many must have sucked in dirt before seeing it broke.

[wistech]

Yes it is just a theory . In effect the airbox is insulating the intake air from the searing hot frame rails and blocking heated air from the radiator. Drawing cooler air right from the narrow gap in the seat instead. Geeze what a crappy design. Kinda up the creek in both options. For those looking for to get the last few ponies it will need to be tested. On the quads we know the cyclone open pod filter gets the job done for the performance engines but here pretty much anything you can do conventionally is a comprimise. This is an R@D project and will need testing to come up with the system that works. Personally I feel this is looking like something extreme will have to be done to get the same intake performance as the quads enjoy. I believe like Boomer that this is a bike and any performance engine will be such a vast improvement over stock that it might not justify the effort to spend the $ for dyno testing and the designing something better. So far we have ZERO data to go on and as we all know from Cannondale history how well things turn out from best guesses. I think somebody else needs to step up here to do the testing because I dont have the time ,money or motivation on this one. Off the top of my head there are at least 5 intake mods with pod filters ,cyclones and ported bike stacks I can see to test. Thats about 30+ hours developemnet , 100 dyno runs and probably 10 hours of dyno time that I cant afford. It was easy with the Kara's quad engine as we had easy access and could swap parts in minutes. I dont think it will be easy on the bikes. If someone wants to throw some financing at the project and some parts I would be willing to help out . I will do a couple simple tests on the stock box and maybe a rudimentary pod filter just to get some basic data but thats about it.