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Old 01-17-2005, 11:16 PM   #16
Esteban
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Quote:
Originally Posted by vrago
I'm in learning mode now,

What do velocity stacks do exactly?

Tuned for what?
Velocity stacks increase the length of the intake tract. This increases momentum of the column of air entering the engine which allows greater combustion chamber filling even when the piston is rising. The inertia of the air column will force more air into the combustion chamber even as the pressure within the combustion chamber rises.

BTW turbulent air rushing into the combustion chamber gives better mixing and more power than smooth air. Makes for a better more complete burn within.

(I have not read this whole thread so my next comment may have already been addressed.)

Beware what you put in your intake tract !! Thin metal vanes could fatigue, crack and get sucked in. I have not seen the ones I read briefly about here, but I have seen cheap poorly designed air filter housings and components do this. Just a note of caution as the results can be expensive.

Steve

Esteban screwed with this post 01-17-2005 at 11:30 PM
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Old 01-18-2005, 05:19 AM   #17
meat popsicle
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Quote:
Originally Posted by vrago
Sicne I do not have a dyno handy and am ot sure how you would run a test on such a modification since its purpose is not really to add any hp. But You all will just have to take my subjective assessment.
You should be able to compare the HP and torque curves with the snake oil on and off the bike to see if there is a change in the onset of torque. That is if you wanna pay for more dyno runs.


Quote:
Originally Posted by vrago
Say what you will, but that c note made me smile. I'd recommend the device to any other heretics who have abandoned the much championed BST.
much championed BST!?! we are the underdogs vrago! it is YOU with the fancy-pants FCR and velocity stack w/ wind vane... we are the faithful!
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Old 01-18-2005, 07:11 AM   #18
creeper
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Quote:
Originally Posted by vrago
I made creeper ride it so he could get dragged into the drama.
Made is the appropriate term. It was difficult to ride with my hands tied behind my back and a farm impliment aimed at my head... but ride it I did.
It felt very much like a BST as far as tractability... but with better snap.
Vrago has lower than stock gearing, so his bike would be snappier anyway, but I was able to lug it down to a what amounted to a fast idle in 4th gear, and pull from that fairly cleanly with just a quick fan of the clutch.
If this is an uncommon occurance with a FCR... then it appears to be money well spent.

Creep

uptight and edgy? you?...
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Old 01-20-2005, 06:16 PM   #19
tcate
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powerNow...

Gents -
I'm an AdvRider newbie and scared to get into the fracas, but...
I ride a YZ250F offroad and, being old, fat, and slow, tend to lug it around a bit more than it was made to do. A friend added a powerNow to his WR and I couldn't believe the difference. I read all the verbage on ThumperTalk - why it will and won't work - and then installed one on my YZ. No jetting changes or anything. Without question, it was the best money I've ever spent. The throttle response, particularly on the bottom-end was unbelievable. The only thing I've noticed is that I lost some of the high rpm snap - it tends to hit a wall at high rpms. But, being a low-rpm-kinda-guy, that hasn't really bothered me much. The bottom line is that it ain't snake oil. Don't know why it works, but don't really care why, just that it does. And it does well....

TC
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Old 01-21-2005, 09:16 AM   #20
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Quote:
Originally Posted by tcate
Gents -
I'm an AdvRider newbie and scared to get into the fracas, but...
I ride a YZ250F offroad and, being old, fat, and slow, tend to lug it around a bit more than it was made to do. A friend added a powerNow to his WR and I couldn't believe the difference. I read all the verbage on ThumperTalk - why it will and won't work - and then installed one on my YZ. No jetting changes or anything. Without question, it was the best money I've ever spent. The throttle response, particularly on the bottom-end was unbelievable. The only thing I've noticed is that I lost some of the high rpm snap - it tends to hit a wall at high rpms. But, being a low-rpm-kinda-guy, that hasn't really bothered me much. The bottom line is that it ain't snake oil. Don't know why it works, but don't really care why, just that it does. And it does well....

TC
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Old 01-21-2005, 11:12 AM   #21
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Old 05-26-2005, 08:39 AM   #22
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I wanted to add something to this thread since we're talking about turbulence and vanes and stuff. I was searching on ebay and came across a "bosley fuel system" modified carb. Hmm I really should keep better track of my bookmarks.. but anyways, I did a little digging and found the dude's patents and it was all very interesting. I'll try to dig it up later as the ebay auction is gone.

The internal carb modifications were way over my head. I mean, it had triggers and weird stuff like that. But he also had a machined piece added onto the motor end of the carb which was easier to understand, and more relevant to this thread. His observation was that backpressure comes mainly along the outer surface of the bore, and so with his motor-side spigot he added a specially perforated extension which left a small gap (1 or 2 mm) between the connecting boot and spigot. It was designed to recycled the backpressure to help with atomization and flow.
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Old 05-26-2005, 06:19 PM   #23
Tholund
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Quote:
Originally Posted by Jinx
"How not to be a sucker" by sending $49.95 +$6.95 S&H to

Jinx
c/o Cardboard Box near Statue of Lenin
Seattle, WA 98112
Hey Jinx,

I sent you my $49.95 but the post office returned it as undeliverable...

Dan
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Old 05-26-2005, 09:42 PM   #24
Doug Matson
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This is probably old news but hear goes, on an FCR with it's pump it will squirt for about 3 seconds stock so most people end up doing the BK mod to reduce the squirt time to about 1 1/2 seconds this helps the bottom end to be crisper that may be why you say the FCR likes to be rolled on instead of wacked open. With the pump time set right the FCR is very a very snappy carb.
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Old 05-27-2005, 08:49 AM   #25
potatoho
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Oops, apologies, it is "boswell fuel system". Here's a picture (off ebay) of the motor side spigot which I described in my last message. Very interesting and I might have to try to make something like it in the future. If you look up Mr. Boswell's patents he describes how it works, as well as the other performance improvements he makes to carbs, but like I said those parts are complicated.

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Old 05-27-2005, 09:06 AM   #26
ChrisC
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Quote:
Originally Posted by potatoho
Oops, apologies, it is "bogswell fuel system". Here's a picture (off ebay) of the motor side spigot which I described in my last message. Very interesting and I might have to try to make something like it in the future. If you look up Mr. Boswell's patents he describes how it works, as well as the other performance improvements he makes to carbs, but like I said those parts are complicated.
fixed
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Old 05-27-2005, 11:19 AM   #27
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Who is the bigger sucker- the guy spending 100 bucks for a powernow, or the guy spending 68k for a bike powered by an ex500?

I have thought about pieceing something like that together myself- pilfering the engine out of the wife's ex.

68 grand... Can't hardly get that through my head... Jesus christ, they should be using brand new 450 twins direct from aprilia for that price. Or from an sv650- which would at least make some power. My 625 makes equal power to an ex. 68k- 5k = 63k for accessories.

J
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